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plumpcars
09-11-07, 05:57 PM
Help! Whilst drilling a 1mm hole today in a block of ally the bit snapped and is stuck in there. The thing snapped a little way in and I have not managed to remove it nor can I see any way of doing so. I need to drill the hole accurately to 4mm and then tap it but it will not drill with the bit stuck in there. Any ideas? Is there a better drill bit that would go through the stuck piece?

jsf55
09-11-07, 06:12 PM
Is there anyway you can mark the hole out from the other side? drill it through at 2mm until you reach the broken piece and punch it out?

plumpcars
09-11-07, 06:35 PM
No, not possible John. It's an ally bar end on and is about 2ft long!

8BB
09-11-07, 06:38 PM
A little bit of heat might expand the ally enough to get it to release it's grip, then use a needle poking it in the drill flutes, to wiggle it out . peace 8bb

jsf55
09-11-07, 07:31 PM
I think heating it is a good idea, but try giving it a sharp tap on to the end the drill is in and see if that disslodges it, might even be worth opening the hole up to 4mm now as deep as ou can safely go?

langysrodshop
09-11-07, 07:51 PM
1mm ??? That's an awefully skinny drill Plump, I think you might be stuffed, The only way i think is to drill down with 4mm as far as you can get and with a bit of heat pick away at it.

What size tap are using to go in a 4mm hole ???

plumpcars
09-11-07, 09:15 PM
I've drilled down with the 4mm as far as it will go and will spend the evening picking. Actually Steve it's 4.1 mm! Works for 10/32 unf.
Thanks all.

jsf55
09-11-07, 09:52 PM
Actually Steve it's 4.1 mm! Works for 10/32 unf.
Thanks all.:eek: isn't that 5/16ths ?

plumpcars
09-11-07, 10:49 PM
:eek: isn't that 5/16ths ?
Sorry! Size 10 tpi 32.....

Alley Kat
09-11-07, 10:59 PM
Steve, there's an engineering place in S.Harrow, Stanley Rd (?), the little industrial estate there. ABC engineering if I remember? Anyway, a few yrs back they got me a well-stuck broken stud out of a bike head by spark erosion. Might be one way if you don't have any luck.

langysrodshop
10-11-07, 09:38 AM
Sorry Steve i'm still abit puzzled why you started off with a 1mm drill, I would of thought that would be asking for trouble or am i missing something ???

plumpcars
10-11-07, 10:11 AM
Hard to explain Steve but I was asking for trouble!

Russ
10-11-07, 10:50 AM
try dropping the end in boiling water it might expand enoughfor the broken bit to fall out ,
Russ

Mart
11-11-07, 02:11 AM
In theory at least you could drill a circle of 1.5mm holes around the broken drill and only have a hole 4mm dia. You might do that just deep enough to expose the end of the broken drill so you could grab hold with something. Then you could clean up with a 4mm drill and tap it out as planned.
Next time don't fanny around with such small drills.
Mart.

Koops
12-11-07, 07:26 PM
Here's some drilling info that might help: http://www.diyfaq.org.uk/powertools/drillfaq.htm

I'd go with the drill either side of the broken drill method. That's if no protruding bits of the broken drill are exposed. If there are protruding 'bits', then heat the alloy and use pliers to ease the broken 'shard' out. If you do drill into the alloy again (either side method), then use a pillar mounted drill for accuracy. Take it slowly too. This should do it. Use quality hardened tipped drills to do the work. These are expensive and maybe you'd actually be best starting with a fresh piece of alloy?