Conversion of stick welder from AC to DC

[rankijr]

I am new to the site. Just signed up this evening after receiving an email from TBN. Have been welding 40+ years (likely not properly) on home projects and equipment repairs.
I have an old 225A Cannox AC stick welder. This welder is very close in design to an old Lincoln 225A AC stick welder. Has anyone been able to convert their AC welder to a DC welder? Any help (advice) on parts and technique would be appreciated. Thanks.

 

[LDCravey]

There are several YouTube videos showing this conversion. Just do a search AC to DC Welder.

 

[dstig1]

As LD noted, there are resources out there to make a rectifier box to do it, but you will probably be both money and aggravation ahead to find a used AC/DC stick welder. They made both versions in the budget Lincoln line in the same basic case (the angled tombstone shape - not talking about the much heavier duty roundtop tombstone- - the Idealarc)

 

[Old Irish]

I have added a rectifier but it was less than awe inspiring. there are some videos on you tube but the one that would be of use for me as a electronicly challenged person came up missing. there was a young fellow who installed a capacitor along with the rectifier on a Lincoln 225 but I was not able to find the video when I started my project. I am pretty sure it would be the same as converting a ac mig to dc and there are scads of videos on that out there but I just never has it high enough on the priority list to pursue it. the rectifier is pretty cheap and straight forward, if I remember correctly for a 225 amp machine you would use a 5000 mfd cap and a pretty high value bleed resistor but I do not remember how it wired in. the result of using just the rectifier was very poor in my opinion but some people on you tube swear it is the best thin since sliced bread. I had every intention of seeing it through but there has just always been other projects that took priority. If you succeed I would like to hear about it for sure.

 

[rankijr]

Thanks to all who responded. I'll give YouTube a try.

 

[Aeves]

I am new to the site. Just signed up this evening after receiving an email from TBN. Have been welding 40+ years (likely not properly) on home projects and equipment repairs.
I have an old 225A Cannox AC stick welder. This welder is very close in design to an old Lincoln 225A AC stick welder. Has anyone been able to convert their AC welder to a DC welder? Any help (advice) on parts and technique would be appreciated. Thanks.

Hello. If you have a way to access what are call "Diodes", you can do it with them. Please note this is a very difficult and costly option. You need methods to cool the diodes, and proper mounting of them. They have two wires coming out and it does matter what wires go where. Unless you are really happy with this machine I'd suggest not doing it. Might cost more than replacing with a new DC machine. If you do want to convert, get hold of an area electrician that understands basic electronics. This person can help you.

 

[Russ]

As others have mentioned, to get a good result involves both rectification (diodes) and smoothing (capacitor) all correctly rated for the high currents involved, plus heat management. And while I'm all for having a go at building your own, if you have a welding store anywhere nearby who will let you demo machines in the store, go and try one of the cheap little DC inverter units - they can do a bunch of tricks on top of just DC (hot start, anti-stick etc) and are amazing to weld with, at least it was for me coming from using an old AC welder from the 1950's.

 

[Norm W]

I picked up a HF Titanium 225 inverter stick machine. It welds great and weighs a bit over 16 lbs. The duty cycle is not up to a "BIG" machine (although I still haven't timed it out) but for the quick repair it is much easier to work with. It also has 110 capability. For the heavy stuff I have a Monkey Wards DC converter for my Miller 225, if I'm going to be doing long sets of welds. Unless you can find at an auction or such a DC converter, by the time you put together the diodes, ballast, cooling fan etc. you might just be better off getting an inverter machine.

 

[rankijr]

I picked up a HF Titanium 225 inverter stick machine. It welds great and weighs a bit over 16 lbs. The duty cycle is not up to a "BIG" machine (although I still haven't timed it out) but for the quick repair it is much easier to work with. It also has 110 capability. For the heavy stuff I have a Monkey Wards DC converter for my Miller 225, if I'm going to be doing long sets of welds. Unless you can find at an auction or such a DC converter, by the time you put together the diodes, ballast, cooling fan etc. you might just be better off getting an inverter machine.

That Monkey Wards DC COnverter has tweaked my interest. I've never heard of it before. I'm going to do some research on it . I have been checking the auctions for some time now. I live in the rural area and like to check out the farm auctions. So far only AC welders have come up for sale. Thanks to all for their replys.

 

[Don_]

I converted my 225 a couple of months ago. It really isn't difficult.
A good practice in electronics is to over build.
Wire gauge is a good example.
Diodes come in all sizes and the maximum amperage should be increased, (like wire gauge)
The diode was in the $50 range and I had capacitors in stock so I used what I had. I wound up replacing the old fan which would not have been necessary had I not broken a blade while testing. It was around $20 - $25 bucks, it's a 220 volt fan so If you replace it keep that in mind.
Here are a couple pictures. I had some aluminum on hand which worked out well for a heat sink. The fan also adds cooling for the diodes & heat sink.








I didn't add a resistor, I give the rod a tap after turning off the welder to discharge the capacitor.

Don_

.

 

[rankijr]

I converted my 225 a couple of months ago. It really isn't difficult.
A good practice in electronics is to over build.
Wire gauge is a good example.
Diodes come in all sizes and the maximum amperage should be increased, (like wire gauge)
The diode was in the $50 range and I had capacitors in stock so I used what I had. I wound up replacing the old fan which would not have been necessary had I not broken a blade while testing. It was around $20 - $25 bucks, it's a 220 volt fan so If you replace it keep that in mind.
Here are a couple pictures. I had some aluminum on hand which worked out well for a heat sink. The fan also adds cooling for the diodes & heat sink.

View attachment 610


View attachment 611

View attachment 612

I didn't add a resistor, I give the rod a tap after turning off the welder to discharge the capacitor.

Don_

.

Thanks for the post. What are the ratings of the capacitor?

 

[harleyron74]

I am new to the site. Just signed up this evening after receiving an email from TBN. Have been welding 40+ years (likely not properly) on home projects and equipment repairs.
I have an old 225A Cannox AC stick welder. This welder is very close in design to an old Lincoln 225A AC stick welder. Has anyone been able to convert their AC welder to a DC welder? Any help (advice) on parts and technique would be appreciated. Thanks.

My father had A very old (late 1960's) Sears AC welder that I learned to weld on ( he was A shipyard welder in WW2 in California) when I took welding during my vo-tech training I realized that an AC/DC machine would be much better than the Sears box but as I was poor as A church mouse in my early 20's I couldn't find one I could afford. I started going to auctions and about 1980 I found A Century DC converter at A hardware store auction. I think I paid around 50 buck's for it and put it on my father's welder and it works very good. I inherited this welding machine in the early 1990's when my father had A detached retina and went blind in that eye and decided to give up welding at age 72.
Century is owned by Lincoln now but I don't know if they still sell DC converter boxes.

 

[Don_]

Nothing calculated here, I just grabbed the first one I came across and threw it in.
I did try striking an arc with and without, it was better with the cap in place. One could improve on this, I'm sure.



Don_

.

 

[Don_]

My father had A very old (late 1960's) Sears AC welder that I learned to weld on ( he was A shipyard welder in WW2 in California) when I took welding during my vo-tech training I realized that an AC/DC machine would be much better than the Sears box but as I was poor as A church mouse in my early 20's I couldn't find one I could afford. I started going to auctions and about 1980 I found A Century DC converter at A hardware store auction. I think I paid around 50 buck's for it and put it on my father's welder and it works very good. I inherited this welding machine in the early 1990's when my father had A detached retina and went blind in that eye and decided to give up welding at age 72.
Century is owned by Lincoln now but I don't know if they still sell DC converter boxes.

I can appreciate the poor part, I was in my early 20's when I bought the 225 brand new for about one weeks pay, back in the early 70's. With a wife and new born daughter, it was rough!
It was $129.99 out the door!

Don_

.