Filling small holes in bodywork.... advice please..

[robtheplod]

Hi All

I have several small drilled holes in the rear side of my Mini which were made for screw fittings on arches which I no longer have. I heard an option here is to fill the hole with weld then smooth it down but just wanted to run by the process with you guys to make sure I'm going about it the right way...

1. Sand down small area inside & out of the hole and make sure the hole itself is clean (probably use a small round file).
2. Hold/clamp a small piece of steel to the inside, then from the outside weld in a circular motion in the hole, outside to centre..

Does this sound right???

 

[piman]

Hello Rob,

yes there is nothing wrong with the procedure, but personally I would just fill the hole with weld. The plate behind will tend to trap moisture and so encourage corrosion.
However there is likely to be some distortion and of course the paintwork will suffer.

An alternative is to drill the holes slightly larger, after removing the paint around the hole, and using a countersunk screw and a short piece of tube and a nut to dimple each hole then simply fill with body filler. Paint the inside of the arch afterwards and finish the outside as normal. Better would be body solder, but with good preparation body filler will last.

Alec

 

[Paul.]

Self tapper and rivet holes are easily filled by backing the hole with a piece of copper and welding them with mig, make sure the copper chill is in good contact with the rear of the panel, and leave it there until the weld has cooled, the thicker the copper the better, you want it to take the heat away from the weld rather than the heat conducting into the surrounding panel, larger holes such as wing mirror and aerial holes can also be filled using this technique, but you will need to cut a plate to fill the hole and butt weld it in.

 

[gavuk]

I would use Pauls method using a copper or brass chill,but remember it gets hot ,but the weld won't stick to it .....Works for me every time ....Gav

 

[robtheplod]

so the copper is just to act as a heat sink ?

thanks for the suggestions!!!

 

[Paul.]

so the copper is just to act as a heat sink ?

thanks for the suggestions!!!

Yes, and to give something to support the weld too, the weld wont stick to the copper, think of it as being a bit like a mold to lay molten weld metal on.
It does work, Ive been doing it for as long as i can remember, not just on cars, Ive given up welding those, but I do a lot of machinery guarding refurbs and modifications, they tend to be full of screw holes etc that we need to hide.

 

[gavuk]

They used to teach it at college ,with oxy/acet......called it backing bar or strip at least down here ......used to overhaul and refurbish packaging machinery.....used it for fillings hole before powder coating .....invisible and nat on reverse as well...

 

[Paul.]

They used to teach it at college ,with oxy/acet......called it backing bar or strip at least down here ......used to overhaul and refurbish packaging machinery.....used it for fillings hole before powder coating .....invisible and nat on reverse as well...

Thats exactly what I'm doing, do it quite a lot with tig on stainless as well.

 

[robtheplod]

.. would copper pipe suffice - if i fold and flatten the end over a few times? - that would then give me a handle to hold it in place as well!

 

[piman]

Hello all,

there can be a couple of pitfalls with using a backing plate, namely as most car wings are concave on the inside the heat sink needs to be shaped to the curvature or it will not be effective and if clamped in place care is required not to dent the wing with the clamp.

Alec