Left hand Cobalt drill

This topic has 9 replies, 7 voices, and was last updated 5 March 2021 at 19:32 by Pete..

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5 March 2021 at 15:19 #531885
Raphael Golez
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@raphaelgolez
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
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5 March 2021 at 15:19 #28028
Raphael Golez
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@raphaelgolez
5 March 2021 at 15:26 #531887
Anonymous
Go to Drill Service – more types of drill than you can shake a stick at:

Left Hand Drills

Andrew
5 March 2021 at 15:31 #531888
Tony Pratt 1
Participant
@tonypratt1
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
5 March 2021 at 15:36 #531892
Raphael Golez
Participant
@raphaelgolez
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
5 March 2021 at 15:49 #531901
Jeff Dayman
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@jeffdayman43397
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.
5 March 2021 at 17:05 #531920
noel shelley
Participant
@noelshelley55608
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.
5 March 2021 at 17:48 #531927
Pete.
Participant
@pete-2
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.
5 March 2021 at 19:23 #531953
not done it yet
Participant
@notdoneityet
Pete,

From their website: If you have not registered to buy on line please do and carriage is free on orders over £10nett
5 March 2021 at 19:32 #531956
Pete.
Participant
@pete-2
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.
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