Author Topic: DC Conversion- Lincoln 225 AC Arc Welder  (Read 394 times)

Ulma Doctor

DC Conversion- Lincoln 225 AC Arc Welder
« on: September 04, 2018, 08:55:36 PM »
I did the dc conversion to my old tombstone welder yesterday.
it took about 45 minutes because i mounted a heat sink to the diode bridge and mounted it to the welder from the inside of the cabinet.
you could skip the mounting from the inside, and mount a small piece of aluminum to the diode bridge.
use tek screws to attach the rectifier assembly to the cabinet for ease.
i got the rectifier rated for 1400v and 400 amps- triple overkill- but it should last my lifetime
i used 4, 4/0 cable lugs to make the electrical connections.
i simply cut and skived the cable, then inserted a 4/0 cable lug.
i used a block of iron as an anvil and smashed the cable lug to about 50% of it's original girth and added 3 indentations with a center punch to prevent pull out

after the install and reassembly, i took a couple passes as a test
it worked beautifully

here is a link to the rectifier

https://www.ebay.com/itm/MDQ-400A-Amp-1600V-Silicon-Single-Phase-Bridge-Rectifier-Diode-Metal-Case-USA/142882091671?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

i also made a video for those interested

https://www.youtube.com/watch?v=stYcojU72Bo

here are some pictures too
« Last Edit: September 04, 2018, 08:59:08 PM by Ulma Doctor »
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON

4GSR

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #1 on: September 04, 2018, 09:17:32 PM »
Boy! Those diodes didn't last long on eBay!

Cool conversion!

Thanks for sharing.
Ken

chips and more

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #2 on: September 04, 2018, 09:33:02 PM »
UD ,that's using your noodle. You will never go hungry!...Dave

goodfellow

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #3 on: September 05, 2018, 07:17:17 AM »
I don't think you will get much improvement from installing just a rectifier. A smooth DC output (hence a quality weld) will depend much more on an inductor and smoothing capacitor circuit than just the rectifier alone.

dlane

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #4 on: September 05, 2018, 09:41:25 AM »
I have the Lincoln ac/dc tomb stone and was told the duty cycle would not handle a spool gun welding aluminum, so I bought a tig.
Derrick

Ulma Doctor

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #5 on: September 05, 2018, 09:04:55 PM »
I don't think you will get much improvement from installing just a rectifier. A smooth DC output (hence a quality weld) will depend much more on an inductor and smoothing capacitor circuit than just the rectifier alone.
i disagree,
the original tombstones with DC output, and many other welders i have used over 30 years, didn't see fit to use capacitors, i didn't either-
it welds as great as my miller 250P or any other transformer welder i have used
i took the pepsi challenge, the converted tombstone welds very smooth with very little spatter- even on E6010  ;)
« Last Edit: September 05, 2018, 09:27:44 PM by Ulma Doctor »
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON

Ulma Doctor

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #6 on: September 05, 2018, 09:07:20 PM »
I have the Lincoln ac/dc tomb stone and was told the duty cycle would not handle a spool gun welding aluminum, so I bought a tig.
i heard the duty cycle is around 20% in DC mode on the AC/DC machines @160AmpsDC
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON

Ulma Doctor

Re: DC Conversion- Lincoln 225 AC Arc Welder
« Reply #7 on: September 05, 2018, 09:26:05 PM »
Boy! Those diodes didn't last long on eBay!

Cool conversion!

Thanks for sharing.
thanks Ken,
i guess other people found them too  8)
9 Lathes, 5 Milling Machines, 6 Welders, 2 Surface Grinders, Shop Smith & woodworking stuff too !!!

MIKE WALTON