1/8" cobalt twist drill broken in through hole in CI. There's only about 1/8" of the drill still stuck, but it's resisted pressing out with vise and arbor press. Also broke a carbide EM trying to drill it out. Heated with a torch a bit but probably not enough. Could resort to 20-ton shop press.
Any ideas. I have a day's work already in the piece and would prefer not to have to make another.
You probably already realize this, but at the very least, if you are going to press, be sure to fit pieces inside of it to make sure you don't bend the heck out of it.
Is there any way to warm up the part and then get cool off just the drill bit sticking out?
I've removed small taps with a carbide dental burr. You could also make a hollow end-mill-type cutter. The first might and the second definitely would require that you silver solder a plug in and redrill.
Interesting comments in regards to using heat. That's a waste of time, folks. HSS is very difficult to anneal---and must be cooled at a dreadfully slow rate to be successful. That would require heating the part in an inert atmosphere, to prevent corrosion of the piece, then you'd have to deal with the sure-to-come movement of the heated part, as stresses are relaxed. All in all, using heat isn't going to be a solution.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
I have successfully removed small broken taps with diamond dental burrs. If you ask your dentist nicely, he will probably give you one or two of his old ones for free. Put the burr in a Dremel or its equivalent, and use a microscope (if you have one) so you can see what you are doing. Its not a five minute job, but it works!
Are you trying to push it into the steam chest? It broke off because it got clogged from not withdrawing it to clear the chips. You might try pushing it from the drill point end and back it out. This would help to unclog the chips and release it.
Good luck,
Fred had the best plan in my view, do not forget some penetrating oil, soak it overnight.
Press or better, hammer on a sturdy piece of steel bridged between the bit and a shim same thickness of the chest wall, impact is better than steady press. Patience needed.
Bill Shields wrote:When all else fails (for the next time), soak it in vinegar with a pinch of salt.
I had a similar situation happen to me once and that actually worked! Was a broken HSS tap wedged well down in the hole. At the suggestion of my Father, I filled the top part of the hole with vinegar and let it sit for a couple days and when I came back to dig out the tap, with a completely pessimistic attitude, the tap nearly fell out! LOL
