tap then paint, or paint then tap?

[syrah]

Working with steel, need some 1cm holes drilled and tapped. Want to get the final product powder coated. Should I drill and tap, then paint, or is that a bad idea which will thicken the threads and make them unusable?
Usually I work with aluminum and don't care about rusting, so I just drill after painting. But I'm worried about steel threads rusting hence why I'm considering painting after tapping.

[catalanjo]

With a 10mm metric thread in steel a bit of powder coating won't cause a problem at all....if the bolt doesn't like it, it will eat it, then spit it out or just crush it into oblivion.
Cheers

[syrah]

those holes are going to be just M4 size though.
Paint isnt too hard to scratch away but the primer under it is pretty though.

[JohnYayas]

tap paint re-tap

[dnar]

tap paint re-tap

My method!

Driving a bolt into a tapped hole with some paint or powder coat can wreck an aluminium thread....

[syrah]

tap paint re-tap

I'm trying to understand what this will do compared to just drilling and tapping after painting? Will it leave some "protective layer" of primer and/or paint? Is that the goal with this approach?
Thanks.

[dnar]

I'm trying to understand what this will do compared to just drilling and tapping after painting? Will it leave some "protective layer" of primer and/or paint? Is that the goal with this approach?
Thanks.

All the dirty work is completed before paint. No damage to paint.

Post paint, a quick whiz with the tap to cleanup and done. No lube/taping fluid required. I mount the tap in a battery drill and set lowest torque.

[syrah]

I see. I was assuming that retapping would remove the paint completely. Thanks.

[catalanjo]

It will remove all the paint including primer !

@"Working with steel, need some 1cm holes drilled and tapped." ........ how come the holes got shrunk down to 4mm

4mm is a different matter ... but even so you can probably still blast through with a stainless allen bolt if you are concerned about corrosion. If it gets stuck then just withdraw and tap it as John suggests !

Unless of course the "steel" magically becomes alluminium in the next few posts, in which case you will have to tap whether you like it or not !
Cheers

[NobleGas]

Powder coaters normally have a selection of rubber bungs to put in threaded holes to keep them clear of coating.