Left hand Cobalt drill

Hello to all,

I was pulling out the pulley from my S7 motor which you guys have given a very good advice and it was fixed.

Initially the pulley got stuck as I remember I placed a thread locker years ago as it keeps on unscrewing and I got fed up.

This time I could not unscrew it and stip the head of the grub screw. I could not drill it as I believe its a hardened (unbrako??) screw. I managed to get the pulley out by using a puller but the broken grub screw remained. I tied heating it with a small butane torch to melt away the thread locker but nothing happened.

As I read hear, one solution is to use a left hand drill to extract it out. I have been looking for a left hand cobalt drill but all I get is from ebay and i'm not to confident of the quality. I check on Arc-eurotrade and the reputable seller but all I can see are right hand cobalt drill. I don't want to drill trough it. Any thoughts or advice guys?

Thanks,

Raphael

Edited By Raphael Golez on 05/03/2021 15:20:35

Go to Drill Service - more types of drill than you can shake a stick at:

Left Hand Drills

Andrew

For this application an ordinary drill will be ok, it will either spin the grub screw into the pulley bore or just drill the screw out. From memory the grub screw is shorter than the bore diameter?

Tony

Thanks Andrew.

Tony tried to screw into the bore but i think the thread lock is the culprit. I will try to heat it again with the butane torch. I will also get a left hand cobalt drill.

Raphael

After heating the setscrew and surrounding metal, hitting a small punch in the hex socket of the screw with a hammer, sharply, will often help get stuck screws moving.

Grind a metric hex key that is just to big to a slight taper and tap it into the spoilt hex and try to unscrew, ideally whilst hot. Good Luck Noel.

Andrew, how much is their postage, and do their prices include vat?

They require an account to access this information, unless I missed something, which is entirely possible.

Pete,

From their website: If you have not registered to buy on line please do and carriage is free on orders over £10nett

Thanks, that's pretty reasonable then, do you know if the worm pattern stub drills would be suitable for drilling out a grub screw, they're noticeably cheaper than the other HsCo drills, if they are I might buy a few sizes as I don't think I have any left hand drill bits.