View Full Version : Welder part question????

09-08-2005, 12:06 PM
OK ... I have a craftsman (older) AC stick welder, 220 Amps max.. I took 4 diodes and made a bridge rectifyer and made it into a DC welder... It works ok... The arc is not quite as smooth as other DC welders that I have used in the past. I added a capaciter across the + and - terminals but I do not have a clue what value I need, microfarad wise... I had a pretty big one and when you initally strike an arc it would blow the rod away from the work and make it impossible to initate the arc. So my question is, if possible:

Could somebody tell me how a DC welder is wired and what value of caps are in it?

All parts that I have found only list a part number not a value...

09-08-2005, 01:04 PM
It's a wonder you didn't blow the thing apart! http://bbs.homeshopmachinist.net//eek.gif

Use an inductor coil (reactor) to smooth out the spikes. It can be nothing more than a coil of wire over a core but usually these in the form of a transformer. It's wired in series with the ground clamp.

The capacitor is wired between the + and - output with a bleeding resistor across it's leads. I think this has to be a polarized DC capacitor--Not an AC motor capacitor. I'll have to go out to the shop and look at the value. I'll get back online tonight.

09-08-2005, 02:21 PM
Hummm A "bleeding resistor" ... That would fix the problem..
Now I just need some values.....
Thanks.... I'll check back again tommarow.....

"Its a wonder it didnt BLOW apart"!
I have a pile of "good ideas" in the back that have blown apart. So in conclusion, I guess that they werent really "good ideas"!!
You'll never learn unless you try!

09-09-2005, 01:43 PM

09-09-2005, 06:15 PM
Surplus Center sells a reactor/arc stabilizer for up to a 300 amp welder.It's relatively cheap.I'd start there.I have a gas fired AC/DC Miller(it's an older model) and the reactor/stabilizer looks very much like the one the Surplus Center sells.

[This message has been edited by RD51 (edited 09-09-2005).]

09-09-2005, 06:21 PM
Sorry, I got wrapped up.

The resistor is 25 ohm, 50W.

The capacitor is 59,000uf, 40Vdc, 50 surge.

The reactor is 8ga. solid coper over a laminated core.

You'll have to check your open-circuit voltage and adjust the resistor and/or cap.

Herm Williams
09-09-2005, 09:24 PM
There are no bad ideas, that just proves that procedure don't work. keep expermenting and be safe.

09-09-2005, 09:28 PM
ahidley, I salute your initiative. A number of us talked about making AC/DC welders out of our buzz boxes, but very few actually spent the bread & did the work. I hope you are able to refine your welder to where it works well.