View Full Version : Miller Portable Spot Welder MPS 20T-Modifications??

12-03-2015, 09:38 AM
How do guys modify their spot welders?

I just bought a water cooled 20 KVA Miller spot welder with 18" tongs. I'd like to experiment with it for a while ( different electrode shapes/tong lengths), and I'm wondering if I can temporarily replace the water cooled tongs with air cooled tongs. I'd like to try 6" just to see what 14,500 amps does to a spot! I realize that the duty cycle would drop quite a bit, but for my case I don't care.

Also, since I'll be rebuilding the water tank/pump set up, I'd be keen to hear any and all suggestions of mods you guys might have made to your machine to make it better.


Denis G
12-03-2015, 08:14 PM
I have an MPS-10FT (10kVA) with water cooled tongs. I don't have a pump set up right now, but it is on my "to-do" list. Mine came with a stand and timer and I've use it without the water to spot weld some 16 Ga. (I monitored the tong temperature by touch.) I can post pictures of mine if you're interested. I'm curious to see your pump set up.

12-03-2015, 08:54 PM
Denis G-

Thanks for the info. Your monitoring technique would be a foolproof way to prevent
copper from melting, that's for sure! I hadn't considered trying what you do-thanks.

As to the pump set up that came with the welder- the picture shows it all--a 5 gallon pail with an aquarium pump, in/out plastic lines jammed thru the cover. I took the tongs off today because I will be storing it in a freezing container, and I needed to be sure the tongs were drained. There was water way up in the tips, so their cheap pump in a bucket worked fine.

If you'd like to see it in person, send me a PM- I'm in Milwaukee. And sure, if you have pics, I like pics.


Denis G
12-04-2015, 01:01 PM
Cliff -- Here are some pictures of my two spot welders. One is the Miller that I mentioned above, and the other is a HFT#45690 220V portable:


I'll PM you in a bit after I get some chores done. I'd like to see your welder.