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Fully Hardened Jacobs Chuck?

Tom A

Hot Rolled
Joined
Apr 26, 2009
Location
NW Florida
I picked up a couple Jacobs super chucks recently, a newer style US made 16N, and this older 14 (note, not marked 14N, just No.14, but engraved "ball bearing super chuck")
Anyway, The 14 has a 1" straight arbor, and I want to change it to MT2. I've swapped a number of arbors on Jacobs chucks, and just drill the chuck, and press or drift out the arbor, no problem.
But THIS chuck is different - It seems to have a completely hardened body, which I discovered by ruining a nice drill bit. I never expected that, as they're always soft and easy drilling.
I guess the chipped key socket should have been a give away, but it's a new one on me - Anyone else ever seen one hardened like this? Maybe some kind of special order chuck?
chuck.jpg
 
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Tom A
Purely a SWAG on my part, but from the straight-shank, I infer that this was meant for some sort of high-production scenario such as a Houadille ( ? Sp. ? ) turret drill, a turret lathe, or a screw machine.

All of the above crank out mass production, particularly the latter two. This would require long-wearing chucks.

BTW: I've seen "other than Jacobs" chucks where the straight shank was unquestionably one piece with the drill body. IIRC they were keyless Walden chucks.
 
That's a new one - never seen spalling around a key hole like that. I've drilled out a bunch of Jacobs chucks from tiny to 20Ns and haven't had any issues. I wonder if you could do a file or spark test to an unobtrusive part of it to see if it really is hardened.
 
That's a new one - never seen spalling around a key hole like that. I've drilled out a bunch of Jacobs chucks from tiny to 20Ns and haven't had any issues. I wonder if you could do a file or spark test to an unobtrusive part of it to see if it really is hardened.
Oh, it's hardened all the way to the bottom all right - It instantly blunted a new 3/16" HSS drill bit on low speed, without making any impression in the chuck.
I'm going to try some wedges first, before I invest more in carbide drills than I paid for the chuck ;~)
 
crikey! I bet a masonry drill suitably touched up with a diamond wheel should be able to chew a hole in the bottom if needed. Lots cheaper than a solid carbide drill.

For wedges on that small of a lip, if you can get a washer cut in half between the wedges and the lip if might help stop the lip deforming. That's a problem I've had a few times using wedges
 
A good solid carbide drill would have no problem punching a hole thru the chuck body if I was doing this. The body is probably nitrated case harden, not totally harden thru.
 
I’ve had a couple used superchucks that had MT3 arbors that I couldn’t get off without getting drastic. I just turned the shank to 3/4” and cut it about an inch long thus relegating them to Bridgeport duty.
 
I’ve had a couple used superchucks that had MT3 arbors that I couldn’t get off without getting drastic. I just turned the shank to 3/4” and cut it about an inch long thus relegating them to Bridgeport duty.
Well, I'm not there yet - I'm only just starting in on this one.
I got the arbor out of the other chuck I got with this one, the 16N, this AM.
Easily drilled it 3/8' in the lathe, put in a grade 5 bolt, and popped it out with one handed pressure with my 3 ton Dake - They should all be that easy .......
 
OK - Follow up - I know you've been on the edge of your seats ;~)
I finally got the #14 off - I tried the wedges first - Nope.
I found I had a 1/4" straight flute carbide tipped bit, and so I drilled it with that - Took forever, as the chuck bottom was unusually thick, much more so than the newer 16N.
I found a nice Lawson "Supertanium" bolt, and tried the arbor press first - Nope.
It took a pretty good amount of pressure with the 20T hydraulic press before it let go with a bang - To the point where I was sure the bolt was going to bend.
All good now.
 
I picked up a couple Jacobs super chucks recently, a newer style US made 16N, and this older 14 (note, not marked 14N, just No.14, but engraved "ball bearing super chuck")
Anyway, The 14 has a 1" straight arbor, and I want to change it to MT2. I've swapped a number of arbors on Jacobs chucks, and just drill the chuck, and press or drift out the arbor, no problem.
But THIS chuck is different - It seems to have a completely hardened body, which I discovered by ruining a nice drill bit. I never expected that, as they're always soft and easy drilling.
I guess the chipped key socket should have been a give away, but it's a new one on me - Anyone else ever seen one hardened like this? Maybe some kind of special order chuck?
View attachment 375637
 
Sorry, I had posted, then saw that you had solved the issue. I saw another person also that suggested using cheapo concrete / masonary bits, and sharpening them to get a good edge.
Bj
 








 
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