Lister Engine Forum
General Category => General Discussion => Topic started by: BruceM on May 25, 2019, 12:42:31 AM
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I bought a new group 29 "marine deep cycle" battery to give the clean DC, 24V welding thing a go. They are rated 385 cranking amps so a good match for 100+ amp welding current, and they are what I have in my 120V battery bank now.
I made a 600 uH choke from a gapped 1000watt laminated toroid core; 22 turns, 16 feet, of 6 strands of 12 awg. I gapped the core with a 10" abrasive chop saw blade in my table saw. I only lost 1/4" of blade on the job, but it took 4-500 gallon tanks of air to make the cut. I filled the gap with steel filled epoxy. To save some $ on the trial, I used some heavy jumper cables for welding cables.
The exciting news for me is that yes, I can do it. While regular welders have me running for the hills from EMI headache, this was doable for me.
Welding on 2-12V batteries does work, and as the article I found by a welding enthusiast stated, the choke makes it possible. When I bypass the choke, it's just not possible to maintain an arc and get the puddle going. Alas, I seem to be a bit lower voltage than I'd like- no such thing as long arcing with this setup! 7018 (3/32) rods were a bust, could not maintain an arc and liked to stick and melt the rod. 6013 (3/32) worked, best with positive on the electrode. I'll have to set up some meters on volts and amps and get my neighbor to watch them while I do a practice bead. I'm ordering some 1/8 rods- more current may have better arc length and stability.
I suspect the losses in the jumper cable are not helping, so I will pop for some fat and short welding cables. I may also reduce the turns on the choke. No need for that much inductance, but I goofed on calculations when shooting for 250-300uH. Battery and all cables were cool immediately after a 6 inch test bead.
I'm very rusty, my last stick welding was in 1974. I think with some practice and some fine tuning of the setup, I can do my own welding again.
Yippee!
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Awesome Glad it's working and you can weld. Next, cast iron repair ?
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Next is a small but tall plow blade attachment for a subsoiler/ripper I got for the Kubota tractor. I have ideas about doing trenching for pipes and such by ripping a few passes on the sides and middle of the trench, then plowing it. The ripper pulls easily with the Kubota L2250 and can go down the 18 inches needed, even with rocks.
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Hey Bruce
That all sounds good
Just a couple of thoughts on the 7018s - I guess they're your equivalent of the Low Hydrogen 16TCs I like to use?
Firstly, if the rods aren't fresh & dry, they will perform poorly - hard to strike an arc etc; and the weld may have poor characteristics
Secondly, unlike the General Purpose electrodes, the Low Hydrogen ones are inherently harder to strike an arc with and the technique required to maintain the arc is different - in general terms you need to push the electrode at the work rather than draw it away . . .
However, the Low Hydrogen electrode will give you a very good weld in a short-arc situation and it sounds as if that is what your set-up wants?
More importantly, the Low Hydrogen electrode, imho, will make a better piece of equipment if you're looking at building something like a ripper blade - it will do a better job on good quality steels and it will never allow any slag inclusions. If you do your welding "downhand" but with a slight uphill slope in your direction of travel - to facilitate the slag around the edge of the weld to settle away from your weld - you may be surprised at how well you can do a good join with a small electrode and relatively modest current and several runs
Electrode on positive
Just a thought or two
Glad to hear you are making progress
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Thanks MikeNash, Yes, similar to your 16TC's, I read about the good welding properties of the 7018's and was very disappointed to not be able to use them. As my skills improve, maybe I'll figure them out. Right now, they stick on striking an arc, or the arc goes out immediately. I have not made even the smallest puddle or bead. So perhaps I should put them in my propane oven and heat them up for a few hours?
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The choke resists a change in current in a passive manner; no electronics needed as in the modern DC welder which electronically attempts to maintain a set current by adjusting voltage. I have the choke in the ground lead right at the battery, but I will move it to the electrode lead for the final setup. Anywhere in the welding current path will work.
It helps stabilize the arc as follows: as the current of the arc is starting to be interrupted, the choke will increase the voltage and thus help keep the arc going. Likewise, voltage and current will be reduced by the choke in case of starting an arc.
The modern DC welder is capable of doing this electronically, using high frequency PWM from an excessively high voltage. This keeps things compact and lightweight, but generates massive high frequency EMI from the high current, high speed switching. Just like a typical switch mode power supply, but at 10-100x the current. Emission strength is related to current times frequency times current loop area. The welding cables radiate this EMI, and the welder is very close. Ignoring what this does to the welder, the electronic regulation of current is a technically marvelous; no massive, expensive 40 lb choke is needed.
If you have a voltage monitor on your DC welder, you will find that welding is taking place around 20 volts plus a bit at 100amps of current. Current will increase dramatically as voltage is raised. I think that solar panels have insufficient voltage regulation, so while a bunch of 24V panels in series might work with a choke, I think the voltage may be too wild; open circuit is 44V. If your peak welding current is 125 amps this would still require 3000 watts of PV or better in parallel. I don't have enough PV to try it.
Welding cable size is determined by your max welding current. Small units with 140A limit may use 4 awg., 250A typically use 2 awg., 300a use 1/0. The point is to limit voltage drop in the cable and cable heating. I've ordered some 2 AWG cable, and will have short, 12 foot cables since the batteries with choke are going to be wheeled and portable.
Here's a link to the article which encouraged me to try a choke on a 2 battery setup:
https://weldingweb.com/showthread.php?8996-Welding-With-Car-Batteries-%96-2-ARC-STABILIZER
The one thing he didn't get right was his choke core; ferrites are never used for high current chokes as they saturate easily so that testing by LCR meter (testing with tiny current) will read way higher than the actual loaded inductance. But since he related his methods and materials well, it was a most valuable and well presented piece of research. I have experience re-purposing toroidal transformer cores as DC chokes, since I used two in my inverter project (for keeping ripple off the 120VDC), and could compare them to a commercial E-I core choke made by Hammond. Gapped laminated toroid cores have the advantage of being the most compact and lowest loss for high current, relatively high inductance DC chokes. Still, not cheap or lightweight.
The choke, with 22 turns (16 feet) of 6 strands of 12awg is shown in the attached photo wit the 2 group 29 marine deep cycle batteries. It's a 1000 watt transformer core, with a gap cut via abrasive blade, epoxy filled. I think it would work as well with only 8 feet or 10 turns and would be less likely to saturate at higher currents. Battery jumper cables were used for initial testing and will be replaced with proper welding cables and connectors next week. I will be increasing all the battery connections to some old 1/0 wire I have, with lugs added. The welding cable with use the standard Dinse 10-25 connectors at the to be designed battery& choke rack/cart.
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Hi Bruce
Sounds like progress
Modern inverter welders have made us lazy to an extent as they are so "smart" at holding an arc, whereas the old machines with no electronics weren't as user-friendly and you needed to master the art of striking and maintaining an arc
At work we have a good-quality BOC inverter welder to which I have attached heavy cables with good quality clamps. We also have a little cheap shitter with thin cables and just a spring-clip earth clamp like a car jumper lead - it works almost as well as the good one, up to about 130A
I would say that it shouldn't as there must be lots of resistance in the cheap cables etc etc? But I would guess that the electronics just "try harder" in its case perhaps?
I mention this because, maybe, in your case - absent electronics - the setup has to be pretty right? If that's the case, then a couple of thoughts:
FWIW I wouldn't use the type of earth cable with a spring clamp like jumper leads - I like the ones that are like a small G clamp. Ditto with the electrode holder - rather than the "sprung" ones, I like the ones where you turn the handle to open and close the orifice that the electrode goes into. Equally, I would think the same would apply at both terminals of the battery and at the ends of your choke?
IMHO "big is good" when it comes to battery clamps of any kind and high-current DC loads - I'm sure you understand that; probably better than I do
I have made many sets of long, heavy jumper leads - in our work we'll often find something like a 6-cylinder John Deere engine driving a pump and which has a flat battery but which we can't get a vehicle nice & close to - so we need long leads. Because we put down lots & lots of submersible pumps we tend to have off-cut lengths of the cables we use for them lying around and I use that. I don't know what the MM2 of them is but 'd say the soft copper wire core would be 10mm in diameter? I always buy the biggest, meanest clamps I can find off the NARVA catalogue at Repco - rated something like 400A - and big heavy copper lugs to attach them to the clamps. The reason I mention this is, I wonder if scrap metal merchants would have lengths of something like that lying about?
I have often observed - coming across a motorist with a flat battery being "helped" somewhere by another motorist with a pair of gas-station jumper leads - that they just won't do the job; I guess the accumulated resistance in the thin cables and tinfoil clamps just overcomes the batteries ability to supply current. As soon as I dig out the big cables from the ute - then things tend to turn over and start straight away
Your welder is an interesting project. I'll watch with interest.
And, yes, if the Low Hydrogen electrode comes out of the oven too hot to touch without using leather gloves - then it's arc is smooth and it "flows" lovely. I don't know if the same is true of all electrodes, but I guess it is - I think maybe the coating is hygroscopic?
Good luck
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Hey MikeN, Yes, I'm sure the modern welding machine will compensate for welding lead losses up to a point, to maintain the set amperage regardless of losses in fittings and cable. I'm guessing that I should conserve voltage as well as I can within reason for <150 amp operation. I'll try baking the 7018 rods and let you know how that works.
The batteries were not run down much at all from my practice welds, so I'm guessing the amperage must be fairly low. I'll have to get some help to measure voltage and current. No point in measuring now until I get the new cables and connectors.
Can you show me a link for the type of ground clamp you like?
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I'd much rather be able to use a wire fed "MIG" welder, but for now this will have to do.
Occasionally there are some ebay sellers offering bare cores, but not recently. Any of the custom toroid transformer co's will sell you a core for an inflated price. I had the 1000W transformer left over from my inverter project. It's an Antekinc.com product, my favorite supplier. The secondary wire was 12 awg so I unwound that and reused it for the choke. I cut off the smaller bifilar primary winding. It took almost three hours to unwrap the mylar strip overwrap (which I saved and will eventually put on the choke) and unwind the core, saving the wire on "stick" type bobbins used for manual toroid winding and about an hour to gap and epoxy it. It's faster if you just cut off the covering mylar tape and all the windings.
Wrapping with 6 strand 12 awg is no fun; if I was starting from scratch, more strands of 18 awg might be a better way to go.
I started work on the new plow attachment for the ripper. Plenty of cutting, grinding, drilling and such left to go. I'll get my new welding cables and fittings on Wednesday afternoon, so welding elementary school will continue then.
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Bruce, how do you regulate the current - turn the welder "up" or "down"? Or do you just have to stop/start to control the heat build-up?
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That's the downside, MikeNash, there's no current adjust, though some sort of resistance could be used to reduce current; I found one reference to using length of rebars as a resistor.
The inverter-DC welder method of high frequency switching to regulate current is very technically convenient. In comparison, if I was to have 3-12V batteries (36V) , and regulate linearly in a fashion similar to my current PV regulator which presently uses 7 500V mosfets, linearly driven in parallel with an op amp for current matching control of each one, it might have to dissipate 150 amps at 10 volts or 1500 watts of heat. I'd have to study data sheets but it might need 14 mosfet/op amps or more. Doable but certainly a fan will be needed and a heck of big aluminum heatsink. Not very practical, thus the inverter approach of high speed switching.
Other battery welding enthusiasts have used smaller lead acid battery voltages, so that they could adjust power in 2 volt (individual cells) or 6 volt taps. So more like the typical MIG welder in that voltage is regulated instead of current. I might be better off with a MIG setup on batteries; using solid wire and inert gas saves me the burning flux chemical exposure and does a better job than the flux core. This I have not seen articles on battery driven MIG but I guess I should look.
Edit- It's hard to have an original idea these days. Readywelder.com has a MIG welder that uses 18, 24, 30 or 36V battery power for portable cordless welding. 18 volt is used for thin metals. I would not want the motor wire feed drive in my hand but this is an interesting interesting idea. With inert gas and easily switched batteries a hacked MIG machine could be pretty useful.
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Sparks are a broad spectrum radio emitter. That was my interest in DC welding, in that if you achieve a steady arc with DC you don't have the starting and stopping and all the spark emitted radio emissions. Thus my interest in the passive arc stabilizer method, and staring with a clean DC source.
That said, yes, using the battery welder feels just like a trip to the grocery store, I get wired, some tachycardia, a headache and can't sleep. How much is the burning flux I can't say. Not so bad that I won't use it when I need to, but I wouldn't want to use it every day.
I did see cheap wire feed mechanisms and MIG torch replacements on Ebay. What I didn't find was the gas connection and regulator. It would be well worth the complexity increase for me to use the CO2/argon mix gas instead of the stinky burning flux.
If only I could find a gas capable MIG welder with a ruined inverter on the cheap. I couldn't find one on ebay or Craigslist. A thousand go into waste bins every day, I expect.
Hey MikeNash- I ordered a $20 solid brass C-clamp type welding ground clamp. That seems like a decent way to go for me.
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Any one try one of these?
WWW.multiplaz.com
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> multiplaz.com
Looks like Browns Gas, all ready to go boom !
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Just when you thought there hasn't been much new in welding...
A very interesting, self shielding torch. It's is still an arc welder of sorts- they are carrying electric current to the grounded metal on the ionized gas.
Truly original.
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Hey MikeN, Yes, I'm sure the modern welding machine will compensate for welding lead losses up to a point, to maintain the set amperage regardless of losses in fittings and cable. I'm guessing that I should conserve voltage as well as I can within reason for <150 amp operation. I'll try baking the 7018 rods and let you know how that works.
The batteries were not run down much at all from my practice welds, so I'm guessing the amperage must be fairly low. I'll have to get some help to measure voltage and current. No point in measuring now until I get the new cables and connectors.
Can you show me a link for the type of ground clamp you like?
This is the one I like Bruce, as it's very positive
The little tit on the end will collapse over time, but you just screw it on down. My current one i have had for five or so years. FWIW the manufacturer rates them at "500 amps"
Cheers
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Oh, sorry, Bruce. I posted that before I read that you had bought one
Good luck with the project
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I could not find a "how it works" diagram- dynamically producing enough hydrogen/oxygen gas from the water-alcohol is quite a trick, likewise the high voltage ion stream for welding. I don't care for voodoo products where the operation isn't clearly show including patent numbers, if any.
Of course, I'm one of those guys who feel a product evaluation should include complete disassembly and reverse engineering.
Thanks, MikeNash. The one I ordered is similar.
I built the plow frame and couldn't wait. I welded it with jumper cables and 6013. Crude but I hope serviceable. Next is attaching the plow blade and raised blade "wings". My biggest problem is that my old fashioned, non-electronic helmet filter is so dark I cannot see anything except the small spot of the arc; I often can't see enough of the work to know where that is. Starting the arc utterly blind is also a problem. The fancy electronic ones of course use an unshielded microprocessor so that's not something I can wear. I ordered a crude filter where a tiny PV panel turns on the LCD type filter to try on Thursday...many complain that gives you arc flash blindness as it takes a bit to turn on but I'm going to try it.
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Full sun in Arizona in May, I can't see anything through the welding helmet filter. Nothing. Most of the new helmets have a battery, so they can switch over so fast you won't see the flash. The little PV panel senses light and charges the battery. Brilliant, with adjustable delay for going clear, which seems to be the reason for the microcontroller. I can always reverse engineer the things and design some analog electronics to replace it, but it's a lot of time and effort.
I'm not statisfied yet with the welds; too much included slag and irregular, start and stop beads. I'd rate them barely serviceable.
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FWIW if you can find a way to make Low Hydrogen rods work for you - you may have difficulty with the rods; but you will have NO slag inclusions I would say. Cheers
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This afternoon I should get the new 12 foot #2 awg cables and connectors. I'll use some old 1/0 cable for the interconnects at the battery and choke. I'll re-evaluate the 24V setup after I get that all hooked up and get some current and voltage measurements. The new PV direct powered helmet filter comes on Friday.
36V operation has been well documented by others. It's too much power by most accounts.
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I got the PV powered welding filter insert early. It works, just annoying when it flashes dark and light with my sputtering arc. The ones with a battery and microcontroller have adjustable darkness, sensitivity and delay. Dialed in, they must be sweet. Could have been done in analog easily, doggone it.
At least I can see what I'm doing now until the flashing gets to me, but it still feels like not enough power on 24V. Sure with I could find a 6V marine battery for cheap.
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A mate of mine who welds for a living uses a big magnet for his earth lead.
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I got the PV powered welding filter insert early. It works, just annoying when it flashes dark and light with my sputtering arc. The ones with a battery and microcontroller have adjustable darkness, sensitivity and delay. Dialed in, they must be sweet. Could have been done in analog easily, doggone it.
At least I can see what I'm doing now until the flashing gets to me, but it still feels like not enough power on 24V. Sure with I could find a 6V marine battery for cheap.
Bruce, one thing you can do - if the situation allows - is leave a slightly larger gap than you might normally do when preparing welds.
If you think of, say, butt-welding a pair of 8mm plates. Perhaps you would normally leave, say, a 2mm gap so that the weld can penetrate nicely. And experience tells you that if you leave, say, a 3mm gap, then your weld may tend to burn through. But if you imagine that you need for some reason to make that weld at 80 amps rather than the 110 amps you might normally use - then a 3mm gap (instead of a 2mm one) might just be what you need to artificially improve the "penetration". Not ideal, but do-able
The use of the 8mm plate is just an example, of course. But the principle may be transferrable to a range of situations
Also, of course, if you use 2.5mm rods where you would normally use 3.2mm ones (accepting that you may have to make two or three passes) then that may allow you to work "hotter" with a lower current
Good luck
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I got my new cables made up last night, will do some rewiring to day. Hopefully I can get some help for current and voltage measurement.
Pity 6V batteries cost twice as much as 12V!
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I did some test welds with my new cable setup. Some improvement- with difficulty I can now use the 7018 rods...which as MikeN suggested, don't have slag inclusions. With the 7018, the arc keeps stopping, but I can restart and work back to the still hot old puddle, without pausing for chipping, and I still see no slag inclusion. As Mike said, it 7018 works way better (arc is steadier) pushing the rod instead of dragging it. Thanks, Mike!
I measured the amps and volts, recorded the meters via camera on tripod while welding. I seem to be in the 85-100 amp range most of the time on 3/32 rods, but some blips to 110 and 60. I was using a digital clamp on amp meter so difficult to see the real picture. (Digital curse.) I put the meter between the battery and the choke in hopes of seeing the smoother, average current.
I tried 6011 rods- they are terrible, slag inclusions, bubbles. They are the AC version of the 6010 rods, which I have on order because no one stocks them locally.
I tried a 6013 - 1/8" rod. It seems to work fine, more metal for the same flux, no harder to work with. I didn't check the amperage on that, and I should. Given the problem with slag inclusions with 6013, I think I'm better off getting the hang of the 7018 rods.
I had some trouble seeing with my new welding helmet filter; it's supposedly a 9 when "on". It's a bit too dark for me, and then I realized that my cataracts are probably adding to the problem. An old T shirt taped to the helmet to get rid of back lighting helped, but light is still coming up from underneath, and it's still so dark I can't see well. Plan C- maybe some welding googles, with a 6 filter???
Edit: Current on the 1/8 6013 is about the same, 80-110. Voltage drop on the choke at 100a is 0.4V, as expected for 16 feet, 6 strand 12 awg.
I must drag/work the rods very close, right on the flux edge, can't pull back at all. I will try 36V tomorrow for comparison. Oh, for a 6v battery!
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Decided to skip the 36V as all written reports indicate it's excessive, too high current, splattering mess maker. 30V would be appealing to try but I don't care to blow another $150 for a 6V battery to try it. A linear regulator to hold constant selected current starting with 36V is possible, but needs about 27 NOW/Fairchild linear rated mosfets (and 27 controlling op amps) in parallel due to the high current, a big heatsink and fan. The mosfets are rated about 10 amps at 10V drop, (100W of heat to be dissipated) but for a robust design I'd want to only pull 6 amps each. 160 amps max/6= 27 mosfets and op amps. Possible but impractical. Makes me like the limitation of a fixed 24V welder with stabilizing choke.
In reading more on the web about DC welders, I find that all the old school big name DC welders have substantial DC filtering/arc stabilizing chokes designed in...and buying those "dialed in" chokes as replacement parts for Miller MIG rigs run about $435. and up. I thought it was interesting as 38ac's sage comment about high quality welders being worth the money recently started making lot's of sense, electronics- wise. In the cheapy units, the lack of a well dialed in choke reportedly results in more spatter and more difficulty starting and maintaining arc. Arc smoothness and stability suffers, making welding difficult and poorer quality. A large choke will cost more than the total price of the cheapy switching power supply stick/mig welder. In the better quality "inverter" welders, the arc stabilization is done electronically, allegedly.
I'm dabbling with my poor welding vision issue this week, while waiting for some 1/2 steel plate needed for my latest attempt at a 5" wide trencher-bolt-on to a deep ripper from County Line. My 24VDC arc is so short, and my cataracts (a special MS related type) bad enough that I just can't see enough area ahead of the arc with the shade 9 or 10. I'm going to try to open up one of the $11 active (pv controlled) welding lenses to see if I can add some circuitry to adjust the shade level. Even the fancy digital ones don't allow adjustment below shade 9.
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I tried a gold shade 9 lens in the helmet- with a hood of fabric to stop glare, I can see the work piece just fine in full sun. Yea! I made a permanent hood out of a navy blue shirt fabric, glued with contact cement to the helmet. Once it dries up for a bit in the sun I'll do some test welds.
If the shade 9 is dark enough to weld with, I'll be all set.
I did take one of the cheap PV/auto-darkening lenses apart, though since I had to cut through the glued plastic case, I broke a couple surface mount resistors. I was able to experiment with the LCD and little PV panel. 3V turns the LCD fully dark, 1.5V perhaps 25% dark. It stays dark so is holding the charge if 3V is removed, must be discharged to clear (shorting leads). The PV panel is 6V open circuit in full sun, and 3.5ma short circuit.
There was a battery on the circuit board, and some sort of oscillating circuit, which I could hear on the AM radio right near the board. I suspect charging the 3v battery from the PV, or one of the chips is a micro controller. I may feel better when welding without this on my head.
The LCD could be controlled with some linear circuitry and have no emissions at all, plus adjustable darkness up to shade 11. A bit of a project, as rapid and reliable arc detection will take a fair amount of fiddling, plus switching to a variable darkness very quickly may also take some fussing about; the capacitance of the display must be overcome.
An interesting project if I was getting paid for a couple weeks work, but I'm not that desperate, yet.
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Bruce FWIW I reckon as we get older & our eyesight gets crappier - welding is a lot easier if the work is well-lit, even what we would think of as over-lit
Sure you can weld in bright sun but the auto visor may not like that . . . but if you have a big lamp shining on the work - I have found that better. It seems counterintuitive as the arc is light - but I have found it good
Do you know about diopter inserts for your welding helmet?
Cheers
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I've got an odd type of cataract associated with MS. It's not "ripe" for surgery, yet. With amber tinted aviators that fit well, I can see quite well for driving.
I'm building a rolling box for the batteries and choke, with some storage on top. Down to the welding lead connectors (which oddly have no isolation from the mounting screw) and then some cosmetics. 8" main wheels in case it goes traveling. I'll post some photos when it's completed.
For 1/8 to 1/4 steel, with 7018 and 6013- 3/32 or better, 1/8" rods, it works pretty well once I got used to the DC short arc. MikeNash's tip on pushing and not dragging the 7018 was a game changer; thanks Mike! It just wouldn't stay lit otherwise.
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Bruce, you're welcome of course. Cheers
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I got the trencher welding done, it's over at my neighbors for testing. We need to add more "wings" to keep the diggings out of the trench.
I'd love to add another 6V for hotter rods, but it's not in my budget and it's serviceable now on 3/32-6013 rods. Because this is a choked fixed voltage welder, no long arcing is possible, nor much whipping. It's limiting, but it will do serviceable work.
As a side note, I think direct battery welding might be better with a MIG setup, since that is by design a fixed voltage, and 23V would be well suited to 0.032" wire that is commonly used. A smaller choke or none might suffice, also.
I made a rolling case for the two group 29 marine deep cycle batteries and my custom gapped toroidal choke/arc stabilizer. I used standard welding connectors and made 12 foot, 2 awg cables, brass C clamp grounding connector. I'm using fixed shade 9 glass in the welding hood, which is OK if I can weld in direct sun. I've got a shade 6 lens to try for shaded work.
Floor space in my shop is getting tight so I wanted a small footprint. The front and back are removable. Welding tools in the bin on top. I intended to fill in the sides but decided it was fine open; the batteries are accessible but well protected from an accidental short. I'll give it a coat of gray Behr Ultra once the green Douglas Fir has dried. Pictures attached.
I know you're thinking; why didn't I weld a steel rolling cabinet. I'm cheap, and this was built with about $25 worth of wood. I had the salvaged castors, and paid $8 for the other wheels. Wood also makes me feel safer when connecting cables and such; a wrench touching the frame won't cause a melt down/explosion.
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That's the best-looking welding trolley I have ever seen :)
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Nice trolley!
And an interesting thread, too
Cheers
Stef
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Thanks, Gort, MikeN, Steff. Yes, it was like sloppy, fast and fun furniture work, using construction lumber, exposed screws. A far cry from fussy hardwood furniture/cabinet work.
MIG welders use a fixed voltage regulation, which is just what you get naturally from batteries. The shorted wire feed method to the puddle will cause some spikes in current, and I think it's interesting that fixed voltage proved to be the best regulation scheme for MIG, instead of the current regulation long used for stick welding.
If I ever mess with a direct battery powered MIG type setup, I'd prefer keeping the wire feed motor away from me, instead of the spool gun. I'd have to shield and filter it as I expect the cheap ones are brushed DC motors, and I'd have to make a linear regulator for motor speed control. Stepper motors might also be used for better speed control, and that means a microcontroller to shield and filter, and I could use the soft switched H-bridge PCB board from my low EMF inverter.
A battery powered MIG would be an interesting project and I suspect a far better welder, but for my limited use I think the utter simplicity of the 24V dual marine battery stick welder is OK, even though the fixed voltage regulation (with some current regulation aid from the choke) is quite limiting compared to the fixed (adjustable) current regulation most stick welders provide.
I did have an interesting development when checking out the active welding filter; the small one I bought for $11 was in fact still a radiating EMI source, with a microcontroller. It was just a better design so I had initially missed it with the AM radio at a distance; it only could be picked up right next to the filter. I feel MUCH better after welding using the passive glass filter. No matter how bad my hearing gets, I won't be wearing a digital hearing aid!
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Got a 120VAC powered trickle charger finished today for the 24V welder batteries. It's designed to be left plugged in, and whenever I turn on the inverter for laundry, it will charge at 1.5 amps max to 14.2V x2 (28.4V) and hold it there while the inverter is on. I was motivated to do this when I found that I had a small toroidal transformer on hand that would do the job perfectly. I didn't have a project box the right size, but I did have some light gauge galvanized sheet steel on hand, so I made the box.
It's job is to keep the batteries in good shape when not in use. I designed it to be low stray magnetic field, but I had to make it a small regulated DC linear supply (with bulk capacitors added later after initial testing) when I found that the large current loop at the batteries was causing too much stray field when fed "lumpy" DC. 9000 uF of 50V electrolytics was almost everything I had on hand, and that works fine. Screwed up my perf board layout but oh well. An LM317T linear regulator I had on hand limits current to 1.5 amps, which is fine. Even at these low currents, I had to add a fair amount of EMI suppression for the bridge diodes; 0.1 uF caps snubbing each diode, and common mode chokes on incoming AC and outgoing DC to knock down what's left. The diode noise is stronger than normal because of my 5 step sine inverter with 43usec rise/fall times on each step.
I plan on using a commercial switching battery charger for regular recharging after welder use. I ordered one for $35 that will charge 24V at 10 amps. If that checks out OK, I'll add some EMI suppression and call it good.
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Life would be so much more do-able if I understood how to think through all that stuff . . . But I just don't
Good onya Bruce
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I still use switchers for my computer and projector gear, just have a great effort and expense in filtering. -120dBm from 10K to 2GHz facility filter (military surplus) for the home 120VDC and 12V power, plus 7 stage LC filters at the computer and pedestal for the projector power.
That toroid stays cool, could do more but it's fine for the trickle charger. It's pretty small and is only 60VA. We all get spoiled by the tiny sizes of switching power supplies.
For rapid charging, I'd want 15 amps at 35V secondary, so a 500-800 watt transformer core. At that power level, critical filtering by inductor (another gapped toroidal choke about 5-10 millifarads ) is needed before the capacitors; rectifying and then dumping it directly to capacitors is often done (cheap) but it's rude and lousy PF. So it's a full days work unwinding and rewinding a core, and another days work for a gapped choke. I have a linear regulator design for 10A I could modify for double the capacity (second linear Mosfet, current sensing resistors and op amp to current match the first), so another hand built, custom board.
Then substantial heat sinking and a vented case and building it all.
For $35 I can get a 10A, 24V switching charger that is programmable delivered to my door... I just won't be in the shop when it's charging. The trickle charger I do want to be able to be in the shop.
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My jealousy for MIG welding (a better match for 24V battery power since it's a fixed voltage process) is over. Ends up the most useful shorting method of just feeding the wire into the puddle causes about 100-150 cycles of current surge per second. That would be a massive AC exposure that makes continuous DC stick arc welding look good (for me).
I got the shade 8 lens and it works fine in shade or sun, so I don't have to re-engineer an auto darkening helmet.
I'm still hoping to find a good deal on a 6V battery to add to my 2- 12V batteries to see if that gives me more capability. I may end up hacking a 12V battery down to 3 cells.
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Yep, cutting and plastic welding the case would be a mess, and toxic for me, so I'm holding out for a 6V battery. We're smoked in again last night and this AM from wildfires so my health and enthusiasm is ebbing.
I'm fast charging each 12V battery separately, with two inexpensive commercial 15/3 amp smart chargers. Great product functionally, but hideous EMI emissions; they completely obliterate the entire AM radio band. Very limited options for 24V chargers, and big bucks. One of the 12V marine batteries is 3 years old, the other new, so fast charging separately is better anyway. Maintenance charging at 1.5A or less is presently at 24V. If I added 6V to have a 24/30V option, I just add another 15/3 amp charger, which also does 6V, but would revise the maintenance charger, probably to 3 separate 1.5A chargers as well.
My neighbor finally got his welded projector shielding enclosure back yestetrday. MIG welded 1/8" thick steel, 24x30x24", with a waveguide for light, honeycomb vents, deep lapped 3/16 access lid in the rear. Built to my sketches, doesn't look bad though an amateur welding job. Someone didn't get the basic welding class/chapter on gapping and filling joints from the outside of the box and instead it's lapped joints with welding inside and out. Twice the work, not as good for shielding due to discontinuity of shield thickness. Oh well.
I've noticed that the price of EMI shielding products like honeycomb vents and fingerstock or conductive fabric over foam gaskets have doubled in the last 20 years. And lead times have gotten longer, with virtually no one stocking anything. I had to order the honeycomb vents from Holland to get anything in less than 3 months. It seems not too many hobbyists or anyone else are doing serious EMC work.
I ordered an oxy-acetylene cutting/welding rig last week. Got it yesterday, tanks in a couple days. While sold as Neiko made and Victor-type, it's neither; no flashback arrestors in the handle or otherwise. (I ordered them immediately.) I'm going to try my hand at gas welding and brazing, which is zero EMF exposure, but primarily, I have always wanted a cutting torch. I have the fantasy that with a neutral or oxidizing flame, the acetylene won't do me in, used outdoors. I should be able to turn off the acetylene for cutting once started if it does. A respirator is an option, and I also have a fresh air supplied helmet (with remote blower) if needed.
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Thanks, but I've taken apart a unit with "no batteries" and found...a battery. It's charged by the tiny PV panels which are also used for arc sensing. Battery in itself is no problem to me at all. The problem for me is a live, unshielded microcontroller with connected wires right next to my head. The processor can be in deep sleep mode, with uA draw much of the time. No critical reason for it really (it could all be done in analog), but more nifty features, cheap, using it. The LCD darkness when on can be controlled PWM, as 3V has it fully dark. Likewise, the adjustable time delay before going clear is easy via microcontroller.
I'm satisfied with my fixed glass shade 8 lens for now.
Let us know how you like your new welder once you've had a chance to check it out!
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The emissions from the little unshielded microcontroller is tiny, on the order of a solar calculator but alas, it's right next to my head, with it's frayed wiring from MS. I do use a calculator and digital volt meters, but not for long and at arms length as they do bother me and make me increasingly confused. So I use an analog VOM except where I must have more precise measurement. We forget that before LCD displays, the world was analog and we got along just fine.
As for shielding- the see through LCD itself is connected, and there is no ground available, so it's not very practical to shield. Easier to just remove their tiny electronics board and use the PV panel(s) and drive the LCD with some analog circuitry. I may do it someday, but for now the shade 8 glass works fine. Per MikeN's suggestion, I also have used a 250 watt flood lamp for seeing the deeply in a shadow work better; that helps.
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I had to replace the Optima yellow top in my car; 6 yrs old and seems to have an open cell.
I thought it was prime for some welding experiments. I opened some of the top with a carbide burr, and soldered a copper tab to the center lead connector to make a center tap at 6V. Then cut a slit in the lid I removed for the copper tab and duct taped the lid back on. One 6V side had the bad cell (open under the slightest load but looks fine on volt meter) , as expected, but the other side is in great shape still.
Welding on 30V was an entirely different experience; long arcing is easy, but it's TOO HOT, easy to over penetrate, more spatter/spray. I need to see how it goes on 1/8" rods on 1/4 steel, and practice more with 7018 now that I can long arc and move the electrode around. I did try some 6011 and at 30V it's too hot for 3/32 6011; it eats up the rod fast and I can hardly keep up lest I burn through. On 24V 6011 just won't stay lit. I can see now why arc welders have adjustable current regulation...dialing it in for any rod and material sure would make things easier.
I may open up the Optima again and solder copper tabs at 2V and 4V (26V and 28V total) to give them a whirl.
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I read about the Optima debacle. Johnson Controls owns them now, so they will get on the problem, I hope. I had to buy a battery in town immediately after getting a jump start; otherwise I would have bought one of the other AGM batteries, as I have before. The advantage of the MB 300D is you can motor down the road with OV at your battery...nothing else working but engine and transmission and of course the vacuum door locks.
I soldered in copper tabs in my defunct Optima at 2v and 4V, avoiding the bad open cell. See photos. With just 2V added, I can use 3/32 and 1/8 6013 rods nicely, with a more steady arc. 3/32 7018 also works nicely. Enough better that now I need to find a 2V, 100 AH cell. If anyone knows of a source for such a small 2V cell please let me know. I found them on Alibaba but I don't want 100.
My losses are pretty low in wiring and cables; I used 1/0 welding cable for the interconnects and my 12 foot welding cables are #2. I guess I should record voltage at the electrodes while welding to see... Oh, for just 2 more volts.
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I did some tests while welding, using a camera in video mode on a tripod looking at meters.
At the batteries, voltage swings from 27.1 to 25.6 (-1.5V) with a 110 amp welding current. The only way to fix that is with AGM batteries or Lithium, no thanks on the price of either. All my battery interconnects are 1/0 with soldered connectors. No chance of improvement there either.
Measured at the electrode, the choke, welding cables and connectors are losing another 1.5V. Loaded welding voltage at 110A is 25.6V measured at the electrode to ground clamp on a 3/32 rod, about 150 on 1/8 rod. I've previously measured the choke loss at 0.4V. The welding cables are #2 and only 12 feet long.
I don't see any low hanging fruit for cutting losses further. I could gain only 0.7 volts by rewinding the choke and going to 1/0 welding cables...not enough.
There's so much better welding characteristics with that 1 extra 2V cell that I'm going to try and find one or make one. The Optima cells are too small capacity from age.
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I had to replace the Optima yellow top in my car; 6 yrs old and seems to have an open cell.
I thought it was prime for some welding experiments. I opened some of the top with a carbide burr, and soldered a copper tab to the center lead connector to make a center tap at 6V. Then cut a slit in the lid I removed for the copper tab and duct taped the lid back on. One 6V side had the bad cell (open under the slightest load but looks fine on volt meter) , as expected, but the other side is in great shape still.
Welding on 30V was an entirely different experience; long arcing is easy, but it's TOO HOT, easy to over penetrate, more spatter/spray. I need to see how it goes on 1/8" rods on 1/4 steel, and practice more with 7018 now that I can long arc and move the electrode around. I did try some 6011 and at 30V it's too hot for 3/32 6011; it eats up the rod fast and I can hardly keep up lest I burn through. On 24V 6011 just won't stay lit. I can see now why arc welders have adjustable current regulation...dialing it in for any rod and material sure would make things easier.
I may open up the Optima again and solder copper tabs at 2V and 4V (26V and 28V total) to give them a whirl.
Here's a thought for you, Bruce
This is something often done when you are welding and find that you have set the welder 5 amps too high but you're in the middle of something a bit critical, or just don't want to stop
It also used to be common when setting the amps wasn't as easy as just turning a dial
And it's a common technique in positional welding . . .
You can really only get away with it with Low Hydrogen rods as they won't leave you with slag inclusions
Now, as you're working, there's a point at which you have gotten 100% of the penetration you can with your weld, and the whole puddle is just about to turn too liquid and fall through - leaving a big hole. Just before this point, you normally keep moving forward with your weld/puddle, and that's how you know you have gotten a good penetration etc (I'm over-simplifying here, but you get it . . . )
If the welder is turned a bit low, you can sort of sit there moving the puddle from side to side and making slow forward progress and a so-so weld - within reason
But if it's too hot, your options are limited. What sort of happens is that, to avoid making a too-hot, too-liquid puddle and having it all just fall away, you tend to move forward faster than you might like - so that the new, cold metal is taking the heat away from the puddle constantly. You tend to end up with a thin, scrappy weld
But what you can do - if you have Low Hydrogen rods - is move ahead a bit to where new, cold metal pulls some of the heat out of your puddle - and then move back . . .
It only takes a small fraction of a second for your weld puddle to cool from liquid to plastic (sort of) . . .
So if you start your weld and work along, watching as it gets "too" hot - then quickly move the electrode forward, sliding along the metal so you don't lose that arc, about maybe a half an inch - then come back to your puddle which has cooled in the fraction of a second your arc was away from it, and is now just a perfect temperature to carry on welding for another second or so - then move forward quickly another half inch - then back to your weld . . . and so on . . .
What's happening is that you're depositing little bits of weld on the metal "ahead" of your weld and then coming along a second or so later and welding over them. If the whole thing is nice and hot and you keep your arc short and you're using Low Hydrogen rods - it's a controllable process and weld quality can still be very good
It's a technique often used on "vertical up" welding, where, because the "work" is vertical not horizontal, the tendency for the weld puddle to "fall down" is much exaggerated. When the puddle gets too hot - you just move away from it for a quarter or a third of a second or some such and then come back to it as it cools . . .
If you have a google, somewhere there will be temperature charts for the process of arc welding and, because your hot weld is surrounded by cold metal, that cooling from "too hot" to "just right" happens very very fast once the heat source (the arc) is removed
Once you get your head around the physics of what's happening (and you'll understand that better than I do) you can see that moving ahead a little or a lot is an easy way to do a good weld with an arc that's "too hot" and is quite a controllable process
If you watch a video of a pipeline welder "keyholing" a root run - basically blowing right through and then filling back in in one action , so as to be assured of 100% penetration, that's sort of the same process
Have a "play", you'll see
Cheers
As your weld puddle forms a
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30V is way more than a 5 amp problem, it's a 50 amp problem, but your note on how to cope with a bit of overage is a good one.
No US companies seem to make modest sized 2V lead batteries. I looked at lithium batteries, but they seem to be nuts, price wise, to get to 100 AH.
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If you have a 50A problem you can probably go from 2.5mm to 3.2mm rods (or imperial equivalent?) You'll be surprised what you can get away with if you think in terms of moving the heat around a lot. Much more than you would normally think to do. Cheers
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My normal range of thicknesses for stick welding would be 1/8 to 1/4, so rods above 1/8 are impractical. Thinner is tricky, but I did get some 1/16 -7018 rods that work on 24V, which I can try on thinner stock. I was thinking more towards brazing for thinner.
I saw on the web that one bloke used 36V in batteries and then a big adjustable resistor made of heavy steel wire, wound around a large cement paver. He clamped on the wire with a jumper cable clamp at differing locations to change his welding voltage/current. This would be a short lived thing, as the steel wire will oxidize, but the concept could be improved by using nichrome wire to avoid the rust to death of the resistance wire. A zig zag of heavy nichrome on ceramic posts on the side of the welder comes to mind, starting at 30 or less volts. Something to be avoided if possible, but doable.
High frequency PWM to a small filter choke is how current regulation is done in the "inverter" type units, starting with 80V or so. This is about the only way to do it electronically, as the currents are so large; linear transistor control from say 30 or 36V uses them as resistors and the heat dissipation and number of transistors is quite large and impractical. The switching approach using switching power transistors (IGBT or MOSFET) can cope with full on or off with minimal heatsinking by comparison. Only a few switching transistors in parallel needed, too. Alas, the switching approach takes very fast rise/fall time high current gate drivers to overcome the gate capacitance and avoid "letting the smoke out" of the switching transistors. The high current spikes of the gate drivers plus the starting and stopping of diodes and ringing from the fast swinging output generate massive EMI. I can't be near these welders at all. Designing such a high current buck converter from 36V would be the obvious solution for a battery rig, but it does me no good. The direct battery solution with minimal linear (non switching) or no regulation avoids the massive EMI problem entirely. So old school it must be.
I did find one company in China with a listing selling a suitable 2V cell at single quantities. I'll contact them and see...
Having just two selections via welding cable connectors at 24 and 26V would be marvelous.
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Yep, an oil filled container would hold heavy steel resistance wire nicely to prevent oxidization, and the oil mass would keep temperatures down for low duty cycle welding. An interesting idea, Glort, thanks.
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Found some perfect 2V batteries on Alibaba (China), despite the listing stating minimum of 1, they won't sell sell under 500 units. Pity, with 24, 26 and 28V I'd have lots of flexibility.
Adding a 6V battery (30V) and resistance for current limiting may be the more practical approach.
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I took apart a dud 18AH 12V AGM battery to see if a new one might be hacked to have all cells in parallel, thus 108AH at 2V and a good match for my Marine wet batteries. Alas, the cases are glued together internally and not just at the outer edge, and designed in such a way that makes reworking it impossible. For hacking a battery for lower voltage, wet lead-acid is a better bet.
I did some research on the resistance method. Nichrome is out- it's too resistive for the largest (9) gauge available, and large rods around available. It's just not suitable for 120-150 amp welding currents.
Next I looked at steel wire/rod. About 4 meters of 3/16 iron rod would give the needed max of 4V drop from a 6V battery at 120 amps. That could be wound on the side of the welder and held on some sort of hold offs. Resistance does vary greatly with alloy so testing would be needed.
Stainless steel rods of 3/16 diameter are more electrically resistive than mild steel so only about 10 feet or 3 meters is needed. With special welding rods, SS can be arc welded, so the rods could be connected together in that manner. Stainless might hold up OK with direct air exposure, a big plus.
My new oxy-acetylene rig is all put together and leak tested on all fittings. It's ready to go but it was getting late so I decided first flame and first cut would be tomorrow AM when I'm fresh and after I've reviewed my proper cutting pressures and start/shut down procedures.
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Fixed taps would be easier, but I have to build something adjustable first to find were to put them. The electrode holder I'm using is bronze jawed with a broad face, brutal spring force. That would be a one way to make a moveable connection.
It cost me $40 last week to have my B tank acetylene plus larger oxy tank filled.
H/O generation via electrolysis cell is an appealing way to turn surplus PV into useful fuels. Compressing them is the scary part, I think. If there's cross contamination due to a leaky separator membrane... BOOM.
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Glad I'm not buying welding gasses in Australia. US- B size acetylene tanks are small, roughly 40 cubic feet of gas, about 1.1 cubic meter. My oxy tank is 80 CF, twice that size.
Separation of the gasses, plus a flash back arrestor for both at the torch plus regulator seems wise for HH/O - electrolysis. I don't know about cutting with Brown's gas; normally a disproportional amount of oxygen is needed so you'd have to have a safe way to vent excess hydrogen pressure assuming the electrolysis cell is being run at some directly useful pressure under 50 psi.
For heating the Brown's gas would be an ideal; for welding I'm not sure. I would think hydrogen alone to mimic the hydrogen rich, oxygen poor inner flame tip region of oxy/acetylene would help prevent oxidization of the weld pool.
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Round two of resistive material calculations, using some better data. Steel varies in resistivity greatly depending on alloy so some variance is to be expected.
Using a desired 4V drop from 6V at 120 amps welding current gives me a desired 0.0333 ohm desired power resistor, with the ability to dissipate the resulting intermittent 480 watts of heat to the air.
For steel rod 3/16" , 4.76mm diameter- 3.29 meters or 10.8 ft (5x 2 foot tall connected rods)
For steel rod 1/4" , 6.35mm diameter- 5.8 m or 19 ft (10 x 2 foot tall connected rods)
For stainless steel rod 1/4", 6.35mm diameter- 1.37m or 4.5 ft (2-3 x 2 foot tall connected rods).
These all seem viable. the 19ft of 1/4" steel rod would stay cooler.
Walmart has a floor polisher 6V battery on sale for $90. Much more than the 100AH needed but the price is right. A complete redo of the wood case will be needed.
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Good point on the max amps draw rate for the floor polisher battery in the store. I can't find the damn thing on line; Walmart's search engine is pathetic. I'm going to have to call and get the make and model so I can check the max current draw specs. Thanks, Glort.
My other two 12V marine deep cycle batteries are 100AH, I was just looking to match that, and use 50ah before charging. Yes, battery voltage sag is a potential issue but I haven't noticed it so far. I took my measurements just AFTER welding (camera recording meters video- I can hear the arcing stop). This is the good case for a linear electronic regulator- it would attempt to hold the specified amperage as battery voltage drops.
Or, for lots of steps or continuous adjustment; welding is not a continuous business and while stopping, manually adjusting for a bit more juice is OK.
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The wet floor polisher batteries seem to be similar to T105's. They have data charts showing 250 amps current draw, so it should be fine for the welder. I suspect that some rural locals may be using them in their small off grid systems. Thanks again for mentioning that important bit which I'd forgotten. 3/16 steel rod is very cheap at Home Depot so I'll start with around 10 feet of that as my 0.033 ohm power resistor.
I can't tolerate sustained welding myself, so there's no problem with stopping to charge while I take a break.
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Lucky break for me, back on Bromelain, which I'd run out of, and once again feeling much less head pain in stores and driving/riding. Did a big shopping run with my neighbor Jeff and got the new 6V battery and the 3/16 rods. Got a nice collection of scrap steel for $10 from the fence co. for my further welding/cutting education, and was offered more to pick over next week. When you've been mostly homebound for a few decades, shopping in stores is a treat.
I've been stewing over using my newer linear PV charge regulator PCB as a welding regulator. It is a low side regulator, 7 TO247 or TO3 style large Mosfets in parallel, linear mode, an op amp and current sense resistor for each for current matching. Very little mods needed though I'm concerned about arc EMI and what I should do to address that. Found a couple Fairchild Mosfets, 75 and 100V that have good linear capability, while still having low on resistance, around $5 ea. One 75V one can handle 50A at 6V drop, with just one, so 7 would be loafing. All together about $100 in parts to build one, not counting what I need for arc EMI supression. Chokes rated 200 amps are NOT standard products. Surge supressor devices might be helpful with some modest line to line metal film capacitors, and perhaps I can get some large ferrite and powdered iron cores.
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Sorry you're down, Glort. The statistics on current SSRI/Tricyclics for depression are quite poor. I've read the books of Datis Kharrazian, quite impressive guy. Teaching at Loma Linda now. https://drknews.com/ I think the future of medicine is in the group now known as functional medicine.
I looked more at the PV board for welding regulator- it was designed for much lower currents and higher voltages so traces and wires for power are going to be a challenge. It would need a spider's web of additional large wires added. I will try the simple resistive method first. Operating MOSFETs in linear mode, you must stay well away from the safe operating area specification, and a massive heatsink will be needed. If dropping 4V at 150 amps, you must heatsink 600W (!), sharing that among 7 mosfets still leaves a very hefty 85W of heat dissipation per mosfet.
Because of short welding duty cycle, either a big slab of aluminum or a water filled heatsink might be effective, sort of a hopper cooled welder. PWM is normally used for this reason. I hope the 3/16 steel rod method will work and will save me a lot of educational lumps in working with such extreme currents and EMI as welding has.
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Hey Bruce - stupid question perhaps. but are these old-fashioned type of welder somethinh you can tolerate?
No electronics, obviously. And I wondered if the pull-in-and-out (voltage?) adjustment might serve you in some way to modify your DC
I would guess there are still a few rattling around Old Farts' workshops
Cheers
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The old school AC welders were just big linear, adjustable step down transformers. No EMI from power switching electronics but horrendous ELF magnetic fields both at transformer and at the welder where the welding leads are separated. Plus some healthy EMI due to AC arc- starting and stopping of the arc generates broad sprectrum EMI. Likewise, those old DC units with linear transformers plus rectification for lumpy "DC" generate a great deal of EMI from the diodes- at start and stop of conduction, diodes make a little burst of high frequency EMI proportional in strength to the current. So old tech doesn't solve the problem, but direct linear use of batteries does get rid of all EMI sources except the actual DC arc start/stop and current variation.
After it stopped drizzling yesterday I did hook up 12 foot of 3/16" diameter mild steel rod along with the extra 6V battery for a total of 30V nominal plus rod resistor. It worked well in terms of welding with 3/32 7018 with the luxury of stable arc and the ability to "whip it". I checked via meters and camera in video mode, the rod was dropping 3.5 V at a current around 110 amps. The rod did heat up quite rapidly, which concerns me, but I hope it will work out OK. Steel electrical resistance increases with temperature. I also tried the same resistance rod from 24V, to see if 1/16" 6013 would then be OK for thin stock. (It's way too hot on 24V.) That results in about 55 amps and while miserable to start and maintain arc, it does work. I tried it on some very thin stock to small square tube and it did the job.
I also tried brazing the 3/16 rod to make a bronze coating for electrical connection. That works fine. My plan is to bronze a spot every couple feet or so, and to use my spring type electrode holder with bronze jaws to clamp to the rod; that will by my simple current adjuster. I'll paint the rest of the rod with high temp spray enamel to avoid corrosion. The fixed end of the rod will connect via 2 gauge wire and welding connector to either 24 or 30V battery connection (and arc stabilizing choke). I bought the screw clamping, type electrode holder to try for the electrode as Mikenash had suggested.
So now I'm ready to build a new case for the three batteries and rod resistor. If I'm not happy with the rod resistor regulation, I'll hack one of my PV regulator boards.
I did some cutting on oxy-acetylene and have no problems with that outside with a light wind. Brazing flux stinks but is doable outside. I haven't tried gas welding with steel rods yet. Much practice is needed on all fronts.
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Hey Bruce, I hadn't realised you were dabbling in oxy/acetylene as well . . .
Check out this product "steel brazing rod"
https://www.globalweldingsupplies.co.nz/range-page.php?sku=R_TWNS
See specs? Especially temp chart?
The general engineer up the road used to use it for things like repairs to truck parts. Said it was really strong & caused less distortion than arc welding in some of his applications
Possibly a mild steel solution up to maybe 5mm or more
Not necessarily that particular product of course - that's just one vendor's take on things. Maybe google "steel brazing rods" or something like that?
Cheers
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I've got some copper coated mild steel filler rods for gas welding, just haven't put in the time yet. That would have the advantage of no flux but more skill is needed since blow out of the base material is possible.
High strength brazing rods like nickel silver are interesting- keeping temperature below steel deformation is a plus.
Back to woodworking today, I must bang up a new case for 3 batteries. I have wire and terminals on order for new interconnects and connection to the steel rod resistor/regulator.
There will be 3 welding connector sockets, one negative, plus 24V, plus 30V. The resistor rod will have a whip to connect to any of these, the electrode cable will have an electrode holder on each end, it always connects to the rod on bronzed spots. That gives me reverse polarity, adjustable low current <=24V, and adjustable higher current <=30V.
Being able to adjust current is a huge help. I hope electronic (linear) regulation isn't needed,
but will see how it works out.
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By my calculations, 26 gauge steel sheet (0.476 mm) in 37.375 mm wide strips will have the have the same cross section as 3/16 steel rod, but has 5 times the surface area for better air cooling. Hmmm, I should get out the tin snips.
The zinc plating will increase conductivity...how much is a subject for testing.
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I made a test welding resistor cut into alternating 1.5" strips as shown in my test setup below. 13 strips total, so roughly 26 feet of 1.5 inch wide 26 gauge galvanized steel sheet. Full length it is providing about 5 volts drop at 85 amps. So the zinc plating is nearly halving the resistance, but that's good for radiating surface area. It doesn't get very hot for a full stick of of welding in one go, so it's a winner. I'll mount it on the new welder case side via some sort of standoffs to get airflow on both sides. I'm still thinking about standoff materials and moveable cable connection.
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.... 26 gauge galvanized steel sheet..... It doesn't get very hot for a full stick of of welding in one go, ....
Mmmmmm zinc fumes if it ever heats up too hot. Be careful.
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Good warning, Mike. This should stay under 250F. It was under 165F, where you can't hold you finger on it for more than 3 seconds. 393F is the max safe temperature for exposed zinc. I'll check it out carefully but thanks very much for the reminder.
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Foil won't hack it, all connected wires radiate, which includes LCD panel and PV panel(s). Can't shield those.
Any sustained electrical arc will generate plenty of UV, so I'm sure plasma cutters do too.
Maybe this winter I'll work on the linear circuitry for the digital one I took apart. I'm doing pretty good with the shade 8 lens, so I'm not in a hurry.
I have the new 3 battery case put together on wheels. Much work left to do, pondering the best way to hook up the "resistor" panel, so I can have either less than 30V, or less than 24V. I had to hook up the whole thing on the shop floor again to weld the 5/8 axle stubs to some steel angle. Sure is easier welding with the right power. I did it with 1/8 6013, almost 3 sticks in fairly rapid order. The galvanized stayed below 210F and rapidly cools while I'm picking slag and wire brushing.
I'm not impressed with the performance below 24V, on 1/16 6013. I tested that yesterday via the resistor on 24V. The arc is tough to start and stops often. I suspect that a much larger choke (which can have smaller wire due to current down to around 50A) might be needed just for low current operating (below 24V). I'm not sure it's worth the effort.
Figuring how to best mount the sheet resistor is next. I want it 2-3 inches out so that there is good upward airflow behind it when it heats up. Wood isn't going to hold up well in direct contact with the metal so I may use some silicone tubing as an insulator.
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Almost done with the new battery welder. The zig zag strip galvanized steel power resistor was enlarged to the whole side of the new larger, 3 battery case, with strips going horizontal so I could use 2.25"x0.75" vertical maple stand offs to attach it. Maple has long history of good heat tolerance. In testing today, I found that thanks to the much longer strip, at the very top of the strip, it does 1/16 - 6013 rods for very thin stock nicely.
What's left is moving the big wheels axle forward a bit and making some sort of push bar for moving it around. I'm very happy with the performance; today I tested several different types and sizes of rods, and marked the best power setting for each right on the strips. In all cases, the sheet steel stays well below 210F.
So, no electronics required, beyond the custom gapped toroidal choke used as an arc stabilizer.
I'll post some pictures soon.
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Here's some pictures of the new 3 battery welder; two 12V marine group 29 and a 6V cart battery, with my custom gapped toroidal choke as arc stabilizer. The case needed a complete redo to house the third battery. It's a bit wider, longer, taller and heavier.
I used it this afternoon for some welding; the push bar for the case was made of some scrap 1" square tubing with 1/16" wall thickness. Since the oxy-acetylene rig is down waiting for a replacement valve body, I tried my hand at stick welding that 1/16 wall tube with 1/16" 6013. Tricky business but I got it done and a decent job of it. I switched to 3/32 rod for welding to the 3/16 thick mounting plates, which was much easier since it's really welding 3/16 with brief excursions to the 1/16.
In the first photo you can see the 26 gauge galvanized strip resistor which is used to limit current from the 30V battery series string. In the top (lowest current, most resistance) setting it is lower current than on straight 24V, which is only useful for 1/16" 6013. This strip has worked out very well, and was dirt cheap to build. The lowest positions marked are for 1/8" 7018 or 7014. The sheet strips have good airflow on the back and front, and stay below 210F so could be directly screwed to the maple stand offs. I'd planned for silicone washers under screw head and strip, but they aren't needed.
In the third photo you can see the custom clamping attachment I made from some scrap 1/4" steel that allows me to easily move to any power setting. I marked the positions with the specific rod size and type determined experimentally. The increments are usefully moderate. It has a soldered on brass welding connector, and solder tinned faces for the clamping electrical surfaces. It needs some spray paint. Polarity reversal only requires switching the cable connectors.
As before, the front, rear and side panels come off for battery removal or service.
I do bulk charging with three "smart" 15A max chargers, Schumacher SC1280 6/12V Rapid Battery Charger and 15A Maintainer ($44 ea), one for each battery. The case is wired with a 6 pin sermos type connector, and now so are the chargers.
Next I'll redo my low power, low EMF maintenance charger, to make it 3 separate chargers as well. The 6V battery requires 2.2 amps at full charge, so I need to order a 3A linear regulator for that. It would be really nice to do it with three secondaries on one core but I've got some old small toroidal transformers that I'll use up instead.
I'm very happy with the new version, my welds have improved greatly with the extra power for "whipping" the electrode and the ability to tune the power for rod and material thickness.
Boring for you who can just use a $100 welder, but a big boon for me.
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Yes, portability has suffered now that it's over 200 lbs. I can still haul it in my trailer, but I'd have to use a come along or block and tackle to winch it up the ramp. Powered wheels would do it but then I'd be out of power before I could start welding. ;)
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Mikenash or other welders- I need to draw on your experience as I'm still novice level. I'm planning a mobile welding table with roughly 2'x4' top.
I've struck out at the 2 area scrapyards looking for suitable material for a welding table top. The two area suppliers won't sell anything less than 4x8 foot sheet stock. What I can get is 20 foot lengths of either 4 inch wide 3/8 flat, or 6 inch wide 1/2" flat. Is 3/8 inch thick enough for a slat type welding table top, or should suck it up and go 1/2 (twice the price)?
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Hey Bruce. FWIW I would say 3/8 is heaps heavy enough if it is well-supported by pieces of steel underneath
If you made the top out of inch plate it could probably be completely un-supported. If you made it from quarter plate it might need support every few inches
If you make it out of 3/8, just by smacking the top around a bit you'll get a feel for what support it needs underneath. And underneath stuff you can knock up out of any old material lying around as no-one will see it . . .
Be imaginative :)
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Hey Bruce!
I have (Knocked down to component level) a 20mm thick solid welding surface 6ftx4ft - The reason its knocked down: TOO DAMN HEAVY TO MOVE!!
What I eventually settled on for minor mobility and stiffness (Price too) was a 6x4ft piece of checker plate - 1/4" thick...
4x Pipe legs at the corner, a 6" vice strategically welded into place, and, as a stiffener, 1x125mm wide galvanized lip channel welded underneath down the center of its length - the required braces are on the legs, the stiffener makes it more than adequate... As a bonus, the lip channel makes a handy clamp point for the earth leads....
Obviously, the rough side of the checker/tread plate is not the top of the bench!
With a decent run up and a sore shoulder later, I can move the thing a few inches at a time!!
Regds
Ed
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Thanks for the good ideas and help, Ed, Mike, Glort.
Yep, mobility does lean one towards a less hefty and cheaper design. I've got some 4 inch all-locking castors which should do the mobility bit. I just have to come up with something to allow the occasional pounding on the vice anvil...perhaps just a wood or steel lift under the vice end to protect the castors. I saw some scrap 1 inch threaded rod at the junkyard which gave me ideas but I expect the price of those nuts would make me wince.
I've done my best looking for some sort of scrap piece for a top and have come up dry. No engineering in these parts, and the fence/fab shop doesn't carry much in heavy sheet.
A slat type welding table top I can make from a single 20 foot 3/8 x 4 inch flat stock for $75, so I'll do that and beef it up with supports as needed as MikeN suggests. Some guy's seem to like slat tops- not my first choice but I can put a piece of Hardyboard over it for non-welding table use. A table with vise to use outside on the 20'x20' shop apron will be very useful for me.
Thanks for the good thoughts, guys!