Filling trim holes (and some random screw holes)

[hotwls13]

Hello all, I'm new to the board and just a week ago got back into the old car/truck thing with my 70 gmc lwb 1/2 ton.

I have previously done very little welding, done some spot welding on floor panels with my cheapy wire feed flux 125 harbor freight welder.

Anyway, that's what I will be using (I know there are much better options but that's what I have and im not buying a better welder). So, I have read about using copper as backing for welding up the holes (even pennies). I've also read that for the really small screw holes I may not need any backer?

How is the copper/pennies held in place? Magnets? I have a couple welding magnets I got for the floor panels.

Thoughts/tips for a newb who is gonna tackle a little welding??

I do know to do small welds, spread out (when doing panels) and then going back after cooling to prevent warping. My truck is rough, lots of previous body work etc. This will never be close to a show truck, I'd just like the panels to be somewhat smooth so I can put a satin paintjob on it and drive it. I guess a "looks good from 20-30 footer". Low budget, beater of a truck that looks cool (to me anyway).

Thanks for any advice.

Again, Please don't suggest I get a better welder. Just not in the budget.

[72HuggerK20]

The copper backing would work fine. Brazing would be another viable option if you have an oxyacetylene rig.

The thing about the HF 125, it's an AC welder. Almost every wire welder should be set up to run DCEN, or DC negative. Even the HF models one step above that are DCEN. It is possible* to convert an AC welder to a DC machine for something to the tune of $50, however, it does take a fair bit of knowledge with electronics.

You can't screw it up too bad though, they're just little holes. Maybe grab a piece of scrap, drill some holes in it, and weld them shut for practice.

[hotwls13]

Originally Posted by 72HuggerK20

The copper backing would work fine. Brazing would be another viable option if you have an oxyacetylene rig.

The thing about the HF 125, it's an AC welder. Almost every wire welder should be set up to run DCEN, or DC negative. Even the HF models one step above that are DCEN. It is possible* to convert an AC welder to a DC machine for something to the tune of $50, however, it does take a fair bit of knowledge with electronics.

You can't screw it up too bad though, they're just little holes. Maybe grab a piece of scrap, drill some holes in it, and weld them shut for practice.

no oxyacetylene.

I planned to start on the back of the cab (while i have the bed off). Previous owner screwed some placard thing to the inside of the cab with 4 sheetmetal screws that are now rusty etc. That way it will be out of view once bed is on in case they are not "perfect"

[72HuggerK20]

With bodywork, it's pretty hard to screw something up beyond the point of repair. Just go for it and learn from your mistakes

[hotwls13]

Originally Posted by 72HuggerK20

With bodywork, it's pretty hard to screw something up beyond the point of repair. Just go for it and learn from your mistakes

Thanks, thats the plan. SO using pennies will work? Have lots of those and they are cheap.

Use a magnet like this to hold the penny on the back?? I have a couple of these

https://www.harborfreight.com/4-3-4-...lder-1938.html

I think I've seen some sort of rectangle of copper on a stick/handle used also?? Is that a better way to go?

[72HuggerK20]

Maybe not, since pennies since the early 1980s have been made of zinc with a copper electroplating layer. I'd go find an 8 inch piece of 3/4" copper tubing and flatten about an inch and a half of the end of it. Leave the rest round so you have a handle.

[B. W.]

I used sheet metal slugs to fill mine. Held in place with magnets. Consider the magnets as expendables, the get destroyed by heat after a few uses.

[hotwls13]

OK, yeah I have a bag of pre-82 pennies (all copper). I think they are worth about 3c each. Haha but the copper pipe will work

And sheetmetal slugs, where do I get those? WHat magnets are u using?

[B. W.]

Just magnets I had lying around. Some are thin & kinda flexible, others are broken bits of speaker magnets. A far as the slugs go, I bought a little kit years ago that had different sizes. Can't remember where I got it.

[hotwls13]

Originally Posted by B. W.

Just magnets I had lying around. Some are thin & kinda flexible, others are broken bits of speaker magnets. A far as the slugs go, I bought a little kit years ago that had different sizes. Can't remember where I got it.

OK cool, I'll look around, those look clean and less welding I'm sure.

FYI I'm going to be filling these holes while panels are on the truck so access behind will be limited in a lot of spots.

[blazer2007]

I,ve used the head of a steel nail and just ground off the tip after I,ve welded it on, makes for a nice handle to hold on too when welding.

[hotwls13]

Originally Posted by blazer2007

I,ve used the head of a steel nail and just ground off the tip after I,ve welded it on, makes for a nice handle to hold on too when welding.

I’ve read about using nails. That would be a cool and cheap way to do it too. I feel like having something to weld into the hole might be better for my cheap flux welder. Might help prevent burning holes??

Also, what do u guys use behind attached panels to keep from catching things on fire?? Welding blankets?? I’m guessing on door panels just make sure the interior panels are removed?? Not much to do about bed panels or fenders

[Bigdav160]

Remember you need to seal the backside of those welds when finished. They seem to rust at a much faster rate than the bare steel the truck was built with.

[mongocanfly]

you can use a piece of copper tubing hammered out flat for a backer.you can put one piece inside the other and hammer flat again to make it a little thicker...the copper i use is 1/4" thick....but remember heat travels very quick in copper so some kind of handle is helpful...if you use nails to plug holes make sure they're not coated with anything...I'd practice first to see what you can accomplish...
just how big are the holes your trying to fix?....I've seen dents pulled out with a puller and they just let the filler go thru the screw holes...not as good as welding but its been done.....

your biggest issue will be l be the flux from your welder....you need to keep those welds very clean..when your just spot welding and trying to overlap welds its going to make things harder....
and like said...make sure you seal the backside..

[hotwls13]

Ok thanks for all the tips guys. I’m still working on the tank relocation and bed fill. Once that is all dialed I’d like to try weld up the screw holes in the back of the cab. But those are pretty small so may not need welded (maybe just filler).

[mongocanfly]

if your gonna try the filler in the holes just make a small dimple around the hole so you can feather the filler out....

[Macdaddy1]

I am new to welding also and my expert welder friend showed me a technique where you weld spots around the 360 degrees to make a dam and then fill in the middle. Grind flush later.

[Jaysonb]

This is what I use, just hold the flat part behind the hole, weld the hole shut. Weld does not stick to the copper. The copper gets hot fast after a couple holes though!