I have broken some tiny 1mm hss drills in stainless trying to open up a 0.9mm hole. Any ideas how to remove the stuck tips. I thought some kind of corrosion might to the trick but not sure how to go about it. Already tried heat, lubes etc and there's not enough to grip. Thanks Andy
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slim_boy_fat
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Is it something you could drill out, re-sleeve then redrill?
We had a tank of acid at work that that would eat hi speed steel but wouldn't touch the stainless apart from giving it a nice shine I can't for the life of me remember what is was, but I'm sure a quick google would bring it up. Or if you have access to the other side you can use a 0.9 mm drill the wrong way round as a punch to knock it out
Would be rather specific to the grade of stainless steel to whether that works.
brightspark
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it would be of some help if we saw what the job is and what way round it if any
Firstly I am a longer term member of this forum but was struggling with signing in issues so created a new account.
I have stainless M8x12 set screws with a 3mm hole down the length just stopping short of drilling thru the head. I then have a .9mm hole drilled into one of the flats to intersect this. I needed to open the hole up to 1mm so got some cheap HSS drill bits from screwfix but stainless being what it is they just grabbed and snapped off when a few mm into the original hole. I have tried heating them up, oil to try and loosen, and a compressor down the big hole to blow them out but they haven't shifted. Tried soaking them in vinegar hoping it would start a rusting process on the HSS whilst leaving the stainless untouched but it hasn't made any difference.
langy
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You will need good drills to drill stainless, cheap ones ain't gonna cut the mustard.
brightspark
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good advice but its a bit late now . any unbranded and cheap cutting tool is rubbish for any material
Not a great deal of help, being such a small diam limits the use of several options, I have ground down Hilti masonry nails and used them as a wrecking punch to break the drill into pieces before, just grind a few MM on the end to retain some strength. And of course do be carefull I hold them in mole grips through a steel plate counter bored to the nails diam to hold them vertical and the plate clamped in place. If they dont shatter you risk knocking them further down the hole, owts worth a try freezer for a few hrs and then some heat??
Stan
Stan
About 20p, the drill bit cost more. It's a shame to bin them though.
gordon stephenson
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The cause of your snapping drill is probably the drills being sharp and with such a small amount to drill out the sharp cutting edge is biting into the stainless and grabbing therefore snapping, Maybe too late now but just taking the sharp edge off the drill would prevent this happening, then just drill very steady and let the drill chip its way down.
Wedg1e
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We've got a similar nightmare at work - or rather, a supplier of ours does 
We sell a range of ultrasonic reference/ calibration blocks that are made to various industry standards. This particular set are 2" solid cylinders of varying lengths from about 0.5" to 6", each with a 1.2mm hole drilled 19mm deep in one end. Out of 19 blocks, 6 have snapped drills stuck in them. Oh and by the way, the blocks are made of titanium
Somewhere in NE England there is a spark eroder tearing his hair out trying to burn away the drills without enlarging the 1.2mm holes...
We sell a range of ultrasonic reference/ calibration blocks that are made to various industry standards. This particular set are 2" solid cylinders of varying lengths from about 0.5" to 6", each with a 1.2mm hole drilled 19mm deep in one end. Out of 19 blocks, 6 have snapped drills stuck in them. Oh and by the way, the blocks are made of titanium
Somewhere in NE England there is a spark eroder tearing his hair out trying to burn away the drills without enlarging the 1.2mm holes...
