Mirror bolt broken

[Popy Fresco]

As per title I ruined one of the bolts that hold the mirror and the fairing.

I tried with a screw removal tool but didn't work, then I cut what was left of the head to leave a flat surface to drill it out but then here came my problem, the drill barely makes some marks on the thing.

Do I need a special drill bit?

Any tips on how to do it?

[tom_e]

Take the nose cone off and see if it's sticking out the other side of the hole in the fairing support, you may be able to get some pliers on it and turn it out.

[Popy Fresco]

Originally Posted by tom_e

Take the nose cone off and see if it's sticking out the other side of the hole in the fairing support, you may be able to get some pliers on it and turn it out.

I have removed the complete thing and the bolt is the lower one where the bracket has some welding on the underside

[Bibio]

you have to drill in stages. start with a small bit then go up till you are just off the size of the threads then wind the swarf out. cutting fluid helps to keep the bit cool. cheep bits are just that and dull in no time. i always use dormer brand bits. keep the speed slow.

[Popy Fresco]

Originally Posted by Bibio

you have to drill in stages. start with a small bit then go up till you are just off the size of the threads then wind the swarf out. cutting fluid helps to keep the bit cool. cheep bits are just that and dull in no time. i always use dormer brand bits. keep the speed slow.

Thanks, will have to try that as I had the drill on max speed as I didn't see any progress

The drill bits I was using were the ones that came with the makita drill, so I was expecting them to be good enough; will buy some dormer anyway as I ruined 2 of them trying.

[Bibio]

TBH a good douse in penetrating fluid should see the threads loose especially since you have heated the bolt stub. also IIR the bolts are SS so you will need SS drill bits 'kerching'.

is there enough thread on the top or bottom to cut a slot? if so then you might be better cutting a slot using penetrating fluid then whack it with an impact driver. once the stub moves then you can just wind it out.

[ophic]

Originally Posted by Bibio

you will need SS drill bits 'kerching'.

A decent HSS drill should go through SS. Might need regular sharpening.

A centre punch might help it bite.

[Popy Fresco]

Have no impact driver and I tried to make a grove for a screwdriver and the thing doesn't move at all. Ordered some drill bits and I will give it another try later this week

Thanks!

[ophic]

Originally Posted by Popy Fresco

Have no impact driver

The manual "hit it with a hammer" type impact drivers aren't very expensive and useful to have.

But when you've got really stubborn "rusted in place for 30 years" head bolts, even hitting one with a sledgehammer doesn't work.

[DuncanC]

You could try diamond glass engraving bits in a dremel. I have had some success with these in the past. Or Ti tipped drills are harder than HSS. The gold standard if you can find one is a left handed drill bit. With these you might get lucky and have the screw undo instead of drilling out.
Be very careful of work hardening the stainless by being timid, don't be brutal but keep a steady pressure on the bit. DON'T keep pecking at it be bold and don't snap a bit in there. Good luck.