Broken drill bit stuck

This topic has 10 replies, 9 voices, and was last updated 5 October 2014 at 10:59 by Ady1.

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4 October 2014 at 20:56 #165621
Wolfie
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@wolfie
I actually got to my workbench today for the first time in ages. Picked up where I left off which was with 2 pieces of aluminium clamped together ready to be drilled through.

The bit promptly broke around half way through the second piece and when I tried again in another hole the (second) drill broke again at around the same point.

2 things arise from this, is there a reason they both broke in teh second piece, was I doing summat wrong??

And how the hell do I get the broken piece of drill out of my piece of ally. Its a hole thats open at both ends but I've hammered and hammered and the bloody thing won't shift

Edited By Wolfie on 05/10/2014 08:35:07
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4 October 2014 at 20:56 #7327
Wolfie
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@wolfie
4 October 2014 at 21:10 #165624
Ian P
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@ianp
An indication of diameter and size of parts involved would help. I have had similar events, sometimes when drifting broken bits of metal out they 'dig in', maybe trying to go slightly sideways and the broken bit effectively becomes embedded.

If the proportions and the metals are amenable, brute force might punch a whole slug of the parent metal out leaving you to a change of design. (bushes, Helicoil etc)

Ian P
4 October 2014 at 21:10 #165625
Neil Wyatt
Moderator
@neilwyatt
Welcome back stranger

Soak it in alum solution and the steel will corrode away over a day or three.

If you ever want to keep the steel not the aluminium use caustic sode instead.

Neil
5 October 2014 at 08:34 #165657
Wolfie
Participant
@wolfie
Its a slab of ally about half an inch thick and the hole is 2.3mm. It was the upper of the two pieces so the hole is right through
5 October 2014 at 08:58 #165659
jason udall
Participant
@jasonudall57142
To recap.

Two slabs of ali..

Same alloy

1.5" thick each

Drill breaks in upper slab before breaking through. .about half way ..ie 0.75" deep

..and twice at approximately the same depth…

So my first thought was lower part moving and "scissor ing" thus gripping the drill ..

It appears not.

If as I have summarised its breaking in the first layer..my guess would be maybe swarf jam

Or an inclusion in material. ..
5 October 2014 at 09:02 #165660
JasonB
Moderator
@jasonb
I've had similar happen when swarf pushed the two plates apart and got stuck in the gap then jamed the drill.

Were you drilling dry or lubricated and how often were you lifting the drill to clear teh swarf?
5 October 2014 at 09:40 #165664
Eric Cox
Participant
@ericcox50497
Same happened to me last week, small diameter drill. It was caused by swarf clogging the flutes. The swarf virtually "welds" itself to the flutes and that's why you're having trouble removing the broken drill. Don't drill too far down before you remove the drill and check the flutes, take your time and check often.
5 October 2014 at 10:38 #165665
Bob Brown 1
Participant
@bobbrown1
Paraffin or similar (wd40) will reduce the swarf sticking to the drill not forgetting to peck drill adding lub as you drill
5 October 2014 at 10:44 #165667
Tony Pratt 1
Participant
@tonypratt1
Lack of lubrication & not clearing the swarf is the likely cause.

Tony
5 October 2014 at 10:59 #165668
Ady1
Participant
@ady1
As mentioned, ally melts onto the cutting edge and welds itself there. I tend to use backgear for turning or drilling ally so there's not enough heat generated to cause a problem
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