Spot welds not sticking?

Oh experienced ones on the board, what am I doing wrong here...

Ground electro-plate off between the panels and where the electrodes will clamp, sprayed with weld-thru primer.

Using Harbor Freight 110v spot welder, squeeze it tight, watch it glow red while I count to '7', hold it tight for a second or two, then release. After I remove my last vise grip it pops apart. All the other spot welds seemed OK but now anything welded by that Harbor Freight spot welder is suspect.

Should I have used the 220v spot welder?

you won't get good welds with a 110v spot welder.

even 220v might be a problem. we have a car-o-liner ctr1200 welder at the body shop where i work at. i think it uses 480V, it has a circular 4 prong plug on it. problem is i think it costs $25K new. we have had it for 6 years now and it's somewhat obsolete already.

ctr1200 strw


a suggestion for you, ALWAYS DO TEST WELDS with comparable conditions on scrap metal and DO A DESTRUCTION WELD TEST on those welds after. i do this EVERY TIME i am going to use the ctr1200.

Simple answer, 110 is not hot enough. IMO

I just drill a hole in the top panel and mig weld the hole up. grind the slag top off to get something close appearance wise and call it a day

Thanks guys, message received - 110v spot welder is a no-go. That also explains why first word at the counter was there was a 20% restocking fee if it was returned.

I did test spot welds on fresh clean sheets of metal scrap pieces - clean and one single path for current to flow is definitely different.

I did MIG rosettes on the trunk pan, I got the spot welder for cleaner welds on the outside body panels.

Looks like good MIG spot weld tips from Eastwood: https://youtu.be/QN9Y9tc7gCs?t=637
Or TIG spot welds: https://youtu.be/3-LSuFsqoWc?t=29

I’ve had very good results with a Miller 220v spot welder. The harbor freight and other import welders look like it, but this unit is able to produce very good and pretty authentic spot welds. I dont have a timer, so i have to test before to get down exactly how long to energize it,but other than that, after getting the tips the right foot print, they look pretty factory. Not really cheap unit, though. I think it was about 750 10 years ago

Thought about it, my MIG rosettes are not presentable. So, I got the HF 240V spot welder and electrical connectors, plugs, box, etc. today. Wired it up and it's much more powerful, bright orange glow instead of red, only need a '3 count' where panels are clean and tight, decent weld nuggets. Test pieces are strong. Problem solved.

Removed original comment, my bad, comments not related to spot welder

Yup. With a little practice, you can replicate a spot weld with minor grinding. I use a Hobart 190 (240v) with C25 mix. Won't work nearly as well with fcaw.

as everybody has already said 110 no go , but if you are patient it can work, first you remove the paint where your contacts meet not where the panels ,if you have good contacts from the welder to metal ,meaning one side gets the juice while the other preforms the ground the paint on the panels where they meet has not bearing on the weld, when you pull the trigger lets the juice from one tip to the other thru the welder and creates a resistance weld. 110 is capable on thin sheet metal but not multiple layers (3 or more). the draw back on 110 is the length of use (2 or 3 welds ) before resistance welder has to cool off , to be efficient. transformer gets to hot to work. that why you a lot of the big shops using Pro-spot or another brand that is liquids cooled. (around 40,000 for a good one) . however there is alternative solution , if you keep your eyes open you can find a Lenco 6000 liquid cooled spotter with different attachments works off of 220 rather well . but again has limitations compared to Pro-spot and others . I personally have 3 of the Lenco 6000 's one set up for wheel house attachments another for the shorter reaches , and reaching about 20 inches. when using you need think out side the box due to reach limitations, build in sub assemblies . . do your research. there are no good cheap tools to duplicate factory assemblies.

Nice: hope you have some extra tips. Become to large for nice welds after so many done. No more then a 1/4" diameter.

Sounds like that machine is not up to the job. I have a Lenco spot welder 220 volts, multiple settings. It can do 1/8” easy. Mine has the timer trigger and became one of the best tools I have, got it at a yard sale for $50, first thought it was a big battery charger. Sell what you have and step up to the big boy toy to get the job done right.

Does it look like one in pic?

I have that welder also, $50 at a swap meet, if you grind the tips to size it makes perfect full penetration welds, needs 60 amps 240. They sell a spot welding clamping setup for it, as well as a pin welder for dent pullers.

I've had no problem doing 2 .062" thick sheets with it. Awkward to get tips aligned, but workable.

Mine doesn’t look like that one, older. I made a plier type gizmo that holds the ends so they come together on the points, about 30” living to points made like a big C. Press together hard, push the trigger. I set the duration and amps before hand.

Can you show a picture id the tool that you made for the welder

I'll 2nd that request. Helpful to those that have such a welder.