Protecting Painted Surface When Tightening A Bolt

[adam1982]

G'day all

Hoping someone out there could share some wisdom on how to protect a painted surface from damage / flaking when tightening a bolt?

Back story - fitting a strut brace and trying to tighten the bolts, however as they need to be rather tight I don't want to damage the paint on the collars - painted them about 2 weeks ago and put a clear coat on aswell

I've tried rubber washers, but as the bolt gets tighter, even the rubber washer is starting to move and has started to slightly damage the paint.

Any ideas ?

Photo below is of the collars

[Daleo]

The best thing to do, is to spot-face the hole; it's like a parallel countersink.

This will give you a flat surface barely larger in diameter than the nut/bolt head that is just below the surrounding metal.

When you tighten the bolt; the paint may end up damaged, but any damage won't propagate past the edge of the spot-face.

[adam1982]

Thanks for the reply Dale

I've never heard of spot-facing? Are you able to tell me a bit more about it or how I'd go about doing it?

Is it similar to the drill bit that you would use in woodworking to widen the top of a pre-drilled hole so that the screw head goes all the way in, sitting flush with the surface? - sorry about the vague description. I'm not sure what it's called or the drill bit that does it is called either lol

[Daleo]

The tool you're referring to is a countersink; same principle.
A picture tells a thousand words.

Exaggerated depth, it will look like this;

You use on of these;

Or grind a drill to make one of these;

[colourclassic]

Instead of rubber washers, why not try thin plastic washers (similar to those used on bike fairings). Obviously strut top mounting bolts require higher torque values (~40ft-lb if my memory is correct) but the plastic washers should still protect the paint from cracking/blemishes. I would have thought rubber washers would 'grab' at the paint, while plastic washers will slide over the surface, reducing cracks and chips.

Edited June 16, 2013 by colourclassic