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Author Topic: Welding on clean DC  (Read 17762 times)

mikenash

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Re: Welding on clean DC
« Reply #15 on: May 28, 2019, 07:17:03 AM »
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

mikenash

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Re: Welding on clean DC
« Reply #16 on: May 28, 2019, 07:23:05 AM »
Oh, sorry, Bruce.  I posted that before I read that you had bought one

Good luck with the project

BruceM

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Re: Welding on clean DC
« Reply #17 on: May 28, 2019, 05:18:46 PM »
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.


BruceM

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Re: Welding on clean DC
« Reply #18 on: May 29, 2019, 06:20:15 AM »
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. 






mikenash

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Re: Welding on clean DC
« Reply #19 on: May 29, 2019, 08:49:28 AM »
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

BruceM

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Re: Welding on clean DC
« Reply #20 on: May 29, 2019, 04:21:53 PM »
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.








« Last Edit: May 29, 2019, 04:47:55 PM by BruceM »

BruceM

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Re: Welding on clean DC
« Reply #21 on: May 29, 2019, 08:04:40 PM »
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.




cobbadog

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Re: Welding on clean DC
« Reply #22 on: May 30, 2019, 06:46:33 AM »
A mate of mine who welds for a living uses a big magnet for his earth lead.
Coopernook - the centre of our Universe.

mikenash

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Re: Welding on clean DC
« Reply #23 on: May 30, 2019, 10:19:47 AM »
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

BruceM

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Re: Welding on clean DC
« Reply #24 on: May 30, 2019, 06:46:14 PM »
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!


BruceM

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Re: Welding on clean DC
« Reply #25 on: May 30, 2019, 11:45:37 PM »
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!







« Last Edit: May 31, 2019, 02:58:26 AM by BruceM »

BruceM

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Re: Welding on clean DC
« Reply #26 on: June 03, 2019, 04:18:03 PM »
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. 


BruceM

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Re: Welding on clean DC
« Reply #27 on: June 03, 2019, 08:09:48 PM »
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.





mikenash

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Re: Welding on clean DC
« Reply #28 on: June 04, 2019, 08:02:03 AM »
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

BruceM

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Re: Welding on clean DC
« Reply #29 on: June 04, 2019, 09:51:49 PM »
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.