Ac/ Dc Ark Welder

[scarecrow]

I picked up oneof those reactors from surpluscenter. It is bigger than I thought. Will go in my DIY welder.

They screwed me on a new geared motor for a wire feeder. They had one that was the right RPM and a lot of torque; looked like a car window motor. Box arrived today, no motor, "Out of stock"

Will try the reactor this weekend. My hand-wound one used stranded wire so was not ideal. Al least I'll be abe to use the 25' of wire from it as a work lead as it was #1 gauge wire.

You should have the pm me I would have been more than happy to give you the dimensions after everything you've done for me and I had a couple of window motor and maybe even the gearboxes and wire drives lying around somewhere I would have sent them to you no idea of the there speeds and ratings though I think they were out of the Mitsubishi Galant

Way to go scarecrow! That's amazing stuff! Well done guys.

I wish I could get my head around electronics and computer programming. Every time I try, either, I get "no... it's not happening" mental blocks. ...I'll get there one day!

If I can do it so can you it's just a matter of reading as much information as you can get tell you get your head around what you need

 

[aero]

I've been thinking about building sometime like this for my Oxford.

Aren't there reactors already in there though, that might not work well with something like this?

 

[shenion]

Yes there is a reactor, usually uses the transformer inductance on AC only machines.

The problem is after adding a rectifier, you need to add capacitors to protect the diodes. The makes the reactor less effective. Adding one after will help maintain a stable arc.

 

[aero]

OK I've been following this and I think I have picked out all the info.

I've drawn out what I understand from this thread.

Let me know if I've got it wrong as I'm going to start to build this. Most MIGs seem to have reactors...I just wondered if one canibalised from an old set would work.

The input from my transformer is 50/80 volts, 20-180 amps

 

[shenion]

The output caps don't need to me motor run caps (you will not find any over about 300uf.) They are just heavy-duty DC electrolytics.

I had recommended a motor run cap as they are easy to find and oil-filled. They will help stabilize the arc a bit and cut down radiated noise. Big caps will increase the output and make starting easier.

What is the voltage rating on the 40k caps you have?

The rest looks fine.

 

[bill_gj]

I've been trying to find out what the rating of the MOV should be - could the learned help me out?

 

[shenion]

The MOV would probabaly be near 200V. Not real critical. If you have lage output caps it really would not be needed.

 

[aero]

Just ben talking to an engineer who has been repairing and building welding sets for over 30 years. Very helpful guy and he's looking out for a secondhand rectifier and inductor for me.

He has said the capacitor on the output is more likely to cause problems when using it for stick welding. OK for MIG as you need a surge to get it going. MIGs yes, always they are constant voltage machine, stick sets are constant current - theres the difference. He did explain why and went on to explain that if I wanted to use it for TIG what I'd have to do to be able to use it with good results.

He seemed to be speaking from hands on experience of buidling and using this type of stuff. No silly warnings that I'd either kill myself and blow up the national grid, just how to make a good unit!

Glad I was able to follow it, just have to turn the theory into practice now!

The MOV I believe is also called a varistor? Rapid electronics do suitable ones in a range of voltages, you want one well over the normal operating volt and well below what the diode goes pop at. 200v seems about right then!

http://www.rapidonline.com/

 

[shenion]

Well, he does not know what he is talking about.

If caps are put on the output, then it will cause problems in either MIG or arc. Since we add caps to the output for stability and noise, the reactor is needed to maintain the arc.

If you left out the caps, you could leave out the reactor.

BTW, MOV - Metal Oxide Varistor

 

[scarecrow]

Just ben talking to an engineer who has been repairing and building welding sets for over 30 years. Very helpful guy and he's looking out for a secondhand rectifier and inductor for me.

He has said the capacitor on the output is more likely to cause problems when using it for stick welding. OK for MIG as you need a surge to get it going. MIGs yes, always they are constant voltage machine, stick sets are constant current - theres the difference. He did explain why and went on to explain that if I wanted to use it for TIG what I'd have to do to be able to use it with good results.

He seemed to be speaking from hands on experience of buidling and using this type of stuff. No silly warnings that I'd either kill myself and blow up the national grid, just how to make a good unit!
http://www.rapidonline.com/

hi aero when you say on the output do you mean on the output of the bridge or the transformer and did you ask him what sort of problems it could cause
because mind seems to be working pretty good with very easy ark start even on low amps the only problem I have I notice just the other day when I was using it on AC was that the capacitor were feeding back into the AC side but this is probably because the rectifier is on A spur from AC output I think I read somewhere that this is not good for the capacitor so I was thinking of putting and isolator switch to stop this happening or just wire the bridge inputs so that I can plug them out when not in use
have you had a look that the hobart Welder diagram there is a link in this thread somewhere for it

 

[shenion]

Yes you will want to disconnect at least one side of the rectifier when doing AC as the caps will restrict the reactance from maintaining the arc.

 

[scarecrow]

I think I have an old isolator switch off a tractor somewhere it should be big enough for the job. Another thing I have noticed is that there isn't that big of a current drop between AC & DC I'm more or less using the same settings maybe slightly higher for DC would this be because it is connected to the same leg from the transformer as AC. Most machines seem to be connected to the second leg of the transformer what is the difference between the two taps. I think one has higher voltage than the other but I'm not sure which is which
did your motors turn up eventually and have you finished your mobile welder must have a look for that tread again

 

[shenion]

Each diode adds about 0.8V of a drop. So 1.6V less in DC. Most use a separate tap slightly higher V to account for this loss.

My airco does have a separate tap and it seems much higher on AC.

I got the feed motor. Made 3 shaft adapters on the old lathe; all wobble Hence my desire for the new lathe. The last one was not bad. Mounted the motor and it pushes the wire about 90% down the torch then runs out of force (motor is rated at 120 in/oz of torque, should be able to push with over 5 pounds). Looked closer and the roller is low, so the wire gets bent in the feeder. Had that on the Lincoln LN7 and it had feed problems (bent feed tube.) Have not had time to mess with it.

I had busted the gas regulator when the tank fell over. Just got the replacement.

Changed the current sense to allow lower currents. With a 2.4mm rod the current setting was at 1/3. Wanted more range. Made change and now output is intermittent. Some connection is loose and have not ahd time to work on it.

With the new lathe and a 5x8 enclosed trailer this week, have been too busy. Spent most of the night rewiring and removing the "redneck" changes to the trailer. Wanted to replace spindles to 5-lug from 6. Odd bearing sizes, spindles, chewed up. Now get to spend weekend doing new axles, spindles. Do get to do welding as new axle is 4" too long.

So little time.....

 

[Jon Moore]

Yes you will want to disconnect at least one side of the rectifier when doing AC as the caps will restrict the reactance from maintaining the arc.

Another "Giant" welder. Others have reported poor support from ebay sellers of these.

Converting AC to DC requires adding a suitable bridge rectifier, some caps and protection devices. An additional reactor will help too.

It depends on how your welder is designed. Some are easy to modify (those with a separate reactor.)

The hard part is the diode bridge. They are expensive and you need ones well over the rated current of the welder.

Been reading and why have you gone with using capacitors and a reactor Infront of the diodes rather than a choke (with or without a capacitor) after the diodes?
Regards

 

[ghostdancing]

wow, after 13 years..

 

[Cobbler]

Is that a resurrection record? Must be close

 

[Jon Moore]

Aha, I always think threads should live on and rather than creating a new one regarding all the info above it's better to keep all relevant information together for other readers.

 

[JMS1972]

I thought this was a spelling mistake but its so old I think the OP really was welding Noahs Ark....

 

[nikos]

The ark welder I was thinking of converting is just an air cooled to 260 amp
it is just your typical air cooled welder has anybody got or know where I could get a wiring diagram with all the parts and the order they should go in

I don't think you need a welder for a wooden ark:=)
Sorry man, couldn't resist....

n

 

[Seadog]

He needs to approach this company

TWI Develops Wood Welding Process

TWI are undertaking further testing on a friction process to weld wood.Having previously explored the process, TWI are now working on joining larger pieces faster than before.

www.twi-global.com