The Stovebolt Site Forums The Shop Area Paint and Body Shop Repairing small, thin-edged holes

Guys,

I'm doing some bodywork on the bottom of a dashboard as well as on the bottom of a door. Both places have a similar repair challenge: there are a couple holes varying in size from about a dime to a quarter (or two quarters side-by-side). It appears that these were rust-throughs as a result of water (or in the case of the dash, probably mouse urine) laying there for a long time. After clean up, the metal surrounding is fairly strong and healthy, but somewhat thin at the edges of the holes. I have access to both a good MIG welder and oxy/acetylene welding, but, given my experience with some similar spots elsewhere on the vehicle, I am concerned with blowing more holes (even though I can dial down my welder to pretty darn low) around the edges of the repair, thus making the holes even bigger. This would be a particular problem with the dash, because the repairs are coming close to the factory holes for cables, accessories, etc.

On the dash, I'm considering using some structural adhesive to attach a couple patch pieces of steel from the back; then filling to flush with filler or JB Weld. I won't have that option on the bottom of the door because I can't quite get access there from the back.

What are your recommendations? Forget this idea and try wire feed or oxy/acetylene welding, or might the patch idea work? I'd appreciate your expertise on this question.

Thanks,

Jim

If you can get a piece of bare copper(i use water pipe smashed flat)clamped tight behind the holes, you can make the repair w/a MIG, you can almost make metal. You want to "stitch" around the outside of the holes & let the metal cool between zaps.

Sometimes its just easier to cut back to thick metal and make a patch than it is to try to deal with thin metal around a hole, even if you think it is small. It doesn't hurt to try, though. If you blow it out you can always just cut it out.

I agree with 4ontheFloor. It's a lot easier to just cut the damage out to good metal and weld in a patch if you have good access.

Welding the edge of sheet metal is tricky and since you have a gas welding setup you could try brazing a patch over the back of the hole and then finishing in with bondo. If it's a real delicate area you could use silver solder or even tin the patch and back of the damaged area and sweat the patch on with plain old solder if heat is a critical concern.

I just came in from working on my truck doors. After removing
the brackets that previously held the old style west coast mirrors,| was left with 10 1/4" dia. holes. I went to a local scrap metal dealer and obtained a 3ft pcs of copper flat bar (the type that is used as a bussbar in a electrical panel) 1/4"thick x1" wide I cut several pcs 4" long and used an end mill cutter in my drill press (looks like a router bit and is used in the machinist trade) & cut flat bottom hole and epoxied 2 rare earth magnets into these holes. 1 on ea end. I am using a Mig Wire Feed .023 wire. I lined up the the copper back up underneath the holes & held in place by the magnets imbedded into each end. The results were very good. I was very impressed. In very little time I had all the holes filled. No clamps required. On the bottom panels I cut out the rust made new patches. I installed a pcs of backup metal behing the patch. Used small sheet metal screws to hold the metal, which were removed as I spot welded along I am pleased to say that the repairs are comming along good. I was also having problems with thin metal burning out. This is info that I received from some of the old timers in my car club. I hope this info can help you as much as its helped me.

Good luck

vickraft:
Where did you get the magnets?

Guys,

Thanks so much for the many good suggestions. I will think about which seem best for my application and give it a try.

JM

Hi Big Chevy 3600

rdavid is absolutely right on the source for these magnets. You wouldn't believe how strong and how well they grab. I got mine at a store called Princess Auto. here in Canada. They are very similar to Harbour Freight type stores. As mentioned Lee Valley also carries them. These are well worth the time to make. I have very little welding experience and I was able to solve many problems in patch welding and filling holes.

Good luck

Just ordered mine from Lee Valley. I got several sizes a total of 18 magnets for $23.00. After ordering I remembered I could probably use one to fix my shower door so it will stay closed. The bullet catch broke and they don't make them anymore.

Guys,

A progress report on the holes, which I've just finished successfully. Thanks again for the good advice. I found that the best results were gained by using a couple hints offered by Vickcraft, using copper backing plates when possible, but also (and even more effectively) using pieces of backup sheetmetal (.022) behind the patches. Once I tacked these in, they gave strength around the thin edges and prevented blow-through in general; and they won't ever be seen from the backside. I used my Hobart Handler 140 on tap 1 and wire speed between 25-30, with C-25 shielding gas and .023 wire. I ended up building up a lot of weld on these holes, certainly probably a lot more than an experienced and skilful welder would have; but with patience I was able to grind them down and they have come out really pretty nicely. On the bottom of the doors, in addition to filling some holes, I also welded in two small patches, wich worked well, using the copper backing sink along the seams. As far as I can tell at this point, these places will need little if any bondo work and should certainly hold well for the life of the vehicle--or at least my life!

Thanks again for the hints.

Yours,

Jim