MT Drills

I have acquired some old MT drills, and several have been rather abused in
the past and the tangs are twisted. What is the best way to fix this -would
heating them up to forge them back into shape cause problems with hardening?
I had considered cutting the ends off the drills and cutting the end off an
old MT adaptor to provide a "bung" that could be used for pushing the drills
out with, but then I thought about how hard this might be. Any suggestions?
Reply to
Kevin Steele
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Kevin Steele wrote in message ...
this -would
If these have had enough abuse to bend the MT shanks are you sure the spiral parts are straight enough to be useable? Possibly worth a check before putting a load of effort in straightening the taper
Try making a split bush and gripping the drill tip in the lathe chuck and rotate by hand to see how bad the run out just where the tang starts.
If they look Ok how about turning the next size MT taper on the end?
Reply to
Bob Minchin
I may have missunderstood here, but can't you just grind the corners off the tang so they will go in? I assume they twisted because the drill wasn't properly seated in the taper, and went round. I wouldn't try forging them as I don't know what will happen to the HSS.
Reply to
Martin L
Yes I could, but there wouldn't be much left to push some of them out of the taper with
They look like it, as the actual drills seem OK just the tangs that are knackered
Reply to
Kevin Steele
The tapers & tangs are not usually HSS, probably not even terribly hard.
You can buy special sockets, like a morse sleeve with an internal flat, grind a flat on the drill taper, bung the drill in & use it with the next size taper. Expensive.
If you're handy with a welding set, some careful building up with weld metal on the tang & grinding back will work. I've done it using fancy MMA electrodes for tool steels, but simple MIG with mild steel wire might be good enough, and easier to build up.
Cheers Tim
Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs
Reply to
. Snip ....
HSS treats cooling at more than 25deg/hour as a quench, so don't worry about annealing them. This is also why you can't soften HSS drills without using a well insulated oven and allowing them to cool down gradually over about 1 1/2 days!
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