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Author Topic: Welder  (Read 845 times)

BruceM

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Re: Welder
« Reply #15 on: August 26, 2019, 04:08:01 PM »
Sorry I completely missed the boat on Au politician murder/prison benefits black humor.

I've not seen any listed PF ratings for cheap inverter/welders- so it is likely 0.6 for those surge loads starting the arc; meaning they are simply rectifying the AC to DC into capacitors on the front end of the inverter-welder. That lops off the top of the sine.   PF correction requires an active buck- boost circuit to take smaller gulps of power throughout the sine, boosting the AC voltage when it's lower than the  DC being created. The PF correcting controller tries to make the load current look like a sine in phase and proportional with the incoming AC voltage. It's much more sophisticated circuitry and also more susceptible to electrical interference; which would be a serious design problem for welder designers. 

There are PF corrected welders out there- for more $.  That might make a CS directly powered MIG welder viable. 

There are MIG spool gun welders sold for direct battery operation; the direct battery voltages are 24-30V, or a MIG wire feed could be used direct off 24V batteries.  If 24V AGM  batteries were used (high charge and discharge current capable) they could be modest size if fed by a high current charger during operation.

That might make a decent automotive alternator type welding setup that a CS could handle.

There are also "portable" battery powered DC inverter welders (MIG).  Here's one:
http://www.weldingtipsandtricks.com/hobart-trek-180.html
This one is for 115VAC charging, and has a small lithium battery.  Spendy at $1200., but would certainly fill the bill for a CS powered welder. 

48V from batteries is too high voltage for useful direct MIG or stick welding and would have to be down (Buck) regulated. 

Budget wise, my 30V ($300 for new batteries) battery stick welder with 3- 15A battery chargers ($45 each) is looking pretty good. The arc stabilizing choke cost me nothing but the 1000W transformer core I gapped would run about $50. new. 
« Last Edit: August 26, 2019, 04:28:10 PM by BruceM »

ajaffa1

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Re: Welder
« Reply #16 on: August 26, 2019, 11:44:03 PM »
Hi BruceM,  I agree that 48 volts is a bit high but 24 is too low, 30 volts is better but how are you achieving this, five six volt batteries and how do you use three battery chargers to charge them?

Perhaps what you are using is three 12 volt batteries each with a charger which would give you a welding voltage of between 36 and 40 volts.

Bob

mikenash

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Re: Welder
« Reply #17 on: August 27, 2019, 02:15:32 AM »
Hi Bruce and Bob

I was thinking of you guys today as I was doing some flanges

Firstly - you're right, there's not enough juice in one of the old CS's to drive a useful welder - it'd be a bunch of compromises.  I'll see if I can find a cheap Lincoln (although I think that might be like a warm icecream or a partial pregnancy . . .)

It's always interesting to hear other folks' takes on settings:  electrode selection, sizes and current . . .

So here's what I would think of as a bog-standard reference piece of work in terms of what I normally do:

It's welding a piece of 12mm wall pipe (half inch in the old money) to a piece of 20mm flat in the form of a flange (3/4 inch).  It's done using a 7018 (my old favourite, which is a Low Hydrogen rod with a bit of an iron deposit action in its flux makeup).  The rod is 3.2mm (I think you'd say 1/8") and it's running at 120A on that little single-phase welder I mentioned yesterday

The comment I would make is that it's hard to imagine a situation - in normal work - where you couldn't get most stuff done with 120A?

That's a single pass and the work is nominally rated at 70,000 PSI test

It's not a particularly pretty weld as I never do pretty fillets - but you could easily achieve the same strength - or functionally close-enough to it - with a root run using a 2.5mm rod at, say, 80A and then a couple of runs with the 3.2mm rod at perhaps 100 or 105A

Although we talk about 220A welders, I don't know where we would use one in what is effectively our "hobby" situations

Just my $0.02  Cheers

BruceM

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Re: Welder
« Reply #18 on: August 27, 2019, 03:04:49 AM »
Bob, my welder uses 2- 110AH, Group 29 marine batteries, and one 200AH 6V floor sander battery. All from Walmart, all $90 to $100 each. The 3 chargers I use are automatic, 6/12 volt capable, 15A max chargers and I have a charge plug with 6 Anderson/Sermos type connectors so each battery is charged separately.  They don't have to "match" that way; one of the 12V batteries is 3 years old, the others are new but obviously grossly mismatched in capacity. It gives me the flexibility to use what's on sale come replacement time. The galvanized steel strip resistor gives me the ability to adjust current; open circuit voltage is the battery series voltage. As the battery charge level lowers I just move the connector down one notch to compensate.  A big 800uH toroidal choke acts as an arc stabilizer, which helps greatly at lower current levels where starting and maintaining an arc is otherwise a real stinker. 

I don't use over 1/8" rods myself, and 3/32 is my most commonly used welding rod.  For thinwall (1/16") tubing or sheet I use 1/16 inch rods and suffer with the greater difficulty in arc starting and stability of low amp welding.  Below that, I must braze since I can't use MIG.

I'm only doing hobby work so battery capacity has not been an issue.  The big deal for me is that I can tolerate using it pretty well outdoors with good ventilation, on a good day.

I found the ideal voltage by cutting up a retired Optima yellow top battery.  What I found is that just one additional cell made 24V (+2v) way better for 3/32 rods.  Two cells extra (24+2+2) was plenty hot enough for 1/8 rods.  I couldn't find a source for 2V 100AH batteries in the US and China manufacturers wouldn't sell less than pallet loads, so I opted for adding a 6V battery and a big power resistor.  The galvanized sheet/strip resistor on the side of the welder has worked out well- stays cool and has good increments of adjustment while dirt cheap.  It saved me having to design, build and test a linear regulator for up to 160A and seems to work adequately.  Arc starting at low currents would be better with an active regulator, and it would automatically compensate for battery fade but I like the utter simplicity of zero electronics.

A 160A adjustable current buck converter on 36V batteries would be perfect if one wasn't impaired by EMI.  The battery interconnects and leads could be #4 AWG since a little loss is OK. 

Mike, I'll be some generator will turn up to operate your nice inverter type stick welder if you just keep your eyes out for it.  7-10KW is a common capacity and might be useful as occasional shop power to supplement a CS for day to day operations.









old seagull man

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Re: Welder
« Reply #19 on: August 27, 2019, 07:15:26 AM »
Sort of on the subject of welders. I have got sick of waiting for the welder. To make my generator frame. For the mighty ZS195  and its 5kw friend.
So i went a bought myself one.  https://www.tradetools.com/product-range/welding-equipment/welding-machines/renegade-140-amp-inverter-arc-welder-20-duty-cycle
 140 amp inverter 10amp power point operastioon gloves, auto dacking mask, an d chipping hammer.
All for $200. even though in a pack of 6018 and so old bits of plate for me to start practicing on.
I last welded in 1975. so this might be entertaining, im thinking.

So all your welding talk has fired me up to have a go.So were do i sign up for lessons.

sirpedrosa

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Re: Welder
« Reply #20 on: August 27, 2019, 08:17:18 AM »
Hi OSM

Welcome to the classroom. Take a seat and enjoy the welding masters lessons.

Have you all a nice day
VP
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx

mikenash

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Re: Welder
« Reply #21 on: August 27, 2019, 08:21:52 AM »
You will be staggered at how much easier starting & holding an arc will be with the new machine compared to one of forty years ago

There are several hundred experts on Youtube lol

But this guy is great :)

https://www.youtube.com/watch?v=8veisgOaHUg

ajaffa1

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Re: Welder
« Reply #22 on: August 27, 2019, 01:28:18 PM »
Hi Guys, when I was welding regularly to meet aircraft standards in the RAF, we had top of the range equipment. The Tig welder I used maxed out at 500 Amps, I doubt I ever took it over 400 Amps, but it was faultless. The trouble with it was that it was bigger than an office filling cabinet and not very portable, much easier to move the airplane than the welder!  :laugh:

Bob

BruceM

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Re: Welder
« Reply #23 on: August 27, 2019, 05:43:21 PM »
Bravo, Old Seagull Man.

I concur with MikeNash, weld.com's got lots of great videos by a pro.  I also hadn't welded (stick) since about 1974.  The  area fence/steel/welding shop sold me a car trunk full of scrap for $10 when I told them I was re-teaching myself to stick weld and needed some scrap for practice.  Nice bunch of guys.

A good tip (at least for me) by another youtube guy- for older, less steady hands, cutting the electrodes in half is a huge help in control.


mikenash

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Re: Welder
« Reply #24 on: August 27, 2019, 06:33:17 PM »
If you watch the good guys online - the have great gear and they know about setup

IMHO if you have good overalls & gloves and a beanie or some such so that you know your head's not gonna get covered in sparks where there's no hair (most) - that's a good start

Then you need to be set up right:  A folded up old pair of overalls where your elbow leans on the table; a bench at a comfortable height, an old office chair to sit on, your work positioned where the lean into it is as natural as can be . . .

Then you need to find mechanical ways to make your hand steady - one hand supporting the other?

If you hold a loop of the cable in the non-welding hand then you won't have a big, swinging loop of welder cable wobbling your electrode . . .

Simple mechanical preparatory stuff

I used to get told at weld school two big things:

90% of a good weld is preparation

(and) Don't set yourself up to fail

Cheers

BruceM

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Re: Welder
« Reply #25 on: August 27, 2019, 06:46:19 PM »
Any thoughts on welding tables?  I've been working on cinder blocks outside, usually under my trees for shade,  but it's hardly comfortable.  The inexpensive portable welding tables like Harbor Freight sells would be a step up, but they seem rather farcical in terms of not being heavy enough to clamp work to.  I don't want to spend a fortune, it's for limited hobby use only. I've thought about going to the scrap yard to see what I can find for a top.  Steel legs and rails I can afford but a heavy top is beaucoup $$$.   I currently often use my rolling table saw with cast iron top and wings as a work table for things I must do outside, and have thought about making a light (removable) gauge steel welding top for it.  I could then at least use welding magnets to hold pieces to it. 




glort

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Re: Welder
« Reply #26 on: August 28, 2019, 01:39:00 AM »


 I currently often use my rolling table saw with cast iron top and wings as a work table for things I must do outside,

Bruce if you are needing to get away from Fumes and the Like, have you thought about putting a fan or blower Behind you?
One of the New gun clubs I used to shoot at had the AC Blowing from behind the Line at the very back of the room.  Given the gun was in front of you and the significant airflow was always behind the shooter, the smoke was always moving away and the air was at the shooters position at least, always 100% Fresh.

I have done this with various things in the shed  Including welding.  I get a fan or a blower ( set up a couple of car radiator fans on a stand now) and put that behind me and If I stand toward the front of the shed everything is blown away from me and out the door.

I'm currently doing Kitchen Renos and yesterday had to cut a channel in the concrete slab.  I got the twin radiator fans and put them on a battery charger for a power supply and set them as I do in the shed, in the window and had them sucking the air out.  I opened the front doors and cracked the doors in the joining rooms and cut the cement.  There was a hell of a cloud of dust as one would expect but it went no where and the room was completely clear in under 30 sec.  I went outside and could see the dustcloud hanging in the still air except where it could be visibly seen to be rushed out by the fans.
Mrs came home ans was suitably impressed all the other rooms were dust free and there was bugger all dust in the kitchen more than about 3M from where I had been cutting and jackhammering.

I like the radiator fans because they move Huge amounts of air. I have one in the shed window powered by a couple od solar panels blowing in.  They keep that tin oven so cool and it's great to work in there in summer because even though the fans are at the back, the strong breeze comes to the front and can be felt anywhere in the shed.  I'm going to add another set in the other window shortly and put the panel to drive them over the top like an awning  to keep the rain out.

Having a fan behind you would allow you to work in your shed but keep your air clean and fume free probably better than being outside with no forced air circulation.  You could even mount radiator fans On your welding cart itself on a telescoping arrangement so you can get the right height and tap to one of the batteries.  Being you are doing stick you don't have to worry about taking the shielding gasses away . The fumes will be moved away straight from the workpiece and you won't get any exposure at all.

If you put the fan/ cart to the side of you and had it blowing out the shed door, that would work just as well.


BruceM

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Re: Welder
« Reply #27 on: August 28, 2019, 06:17:50 AM »
Now that I have the inverter with very low EMI AC, I have thought of getting a fan on a stand for the shop.   Fan motors are problematic when nearby, depending on the power of the motor and stray field of the motor design...so I tend to think of fans last.  The shop has a big doors and a big concrete apron and all my wood/air motor tools are on wheels so I can work outside.   The fan would be useful even outside on still days, though those are few. 

I still need for a welding table; I don't want to scorch and grunge up my main bench, which has a 3 foot by 8 foot maple butcher block top, nor my cast iron table saw top which I regularly use for soldering electronics outdoors.

Once I rebound from this summer's wildfires I hope to be travel worth again and get over to take a look around the scrap yard for something that might be used for a welding table top.
It's always demoralizing to go backwards, health wise.





« Last Edit: August 28, 2019, 06:27:22 AM by BruceM »

mikenash

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Re: Welder
« Reply #28 on: August 28, 2019, 09:03:32 AM »
Hi Bruce

When I came to my current job eight or so years ago they didn't have much engineering/fabrication capacity on site - they just had the local engineers almost next door do almost everything; so over a couple of years I built up stuff so we had some capacity

My boss was sceptical so we sort of did stuff under the radar.  When I needed a welding table I bought a half-sheet of 10mm (3/8 steel). It was only maybe $300 for 1200 X 1200mm 4-foot square, and I made legs out of scrap 2" galv pipe offcuts

Eight years later it still serves as well as ever.  I am forever tacking a bit of something to it to act as a stand or a brace or whatever.  It is GREAT.  It will last for 20 years or maybe more

I reckon you could get away with 8mm (5/16") if you put a bit of reinforcing of some kind under it

This thing has had all sort of sledgehammer-based abuse etc . . .

If you make up a couple of cheap saw-horse style stands about the same height out of any old junk or wood or whatever so they can support longer stuff so that one end is on the welding table - then you are 90% of the way there

BruceM

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Re: Welder
« Reply #29 on: August 28, 2019, 03:28:56 PM »
MikeN- So you like the tack it to the table top method?  That's something an old woodworker doesn't think of...  I was liking the look of slat table top designs where I could employ my large supply of C clamps, but I have seen on youtube vids that some, like yourself, prefer to simply tack weld to the table top.  I have two adjustable height roller stands I use for woodworking, so that's covered. 

A 2'x4' sheet of 3/8 thick A31 hot rolled steel is under $200 online so I'll have to check with the local fence/steel shop to see what price they can get for me.