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Old 09-07-2019, 11:46 AM
Don_S Don_S is offline
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Join Date: Mar 2005
Location: Tenville, IA
Posts: 556
Unhappy Spun the chuck on the JT shank

Looks like I overdid it trying to drill a 1" hole in HR steel with my Rhom chuck and R8 adapter. Spun the Jacobs taper joint between the adapter and the chuck. The tapers look ok. I wan only going 80 rpm and it caught breaking through and exceeded the holding power of the taper.

Had to use two wrenches to get the drill out of the chuck as it had self tightened enough that the torque to loosen exceeded the holding power of the Jacobs taper.

I guess it's time to get an integral chuck for the big holes. I need to get a good ball bearing chuck suitable for power tapping. The Rohm chuck doesn't get enough bite on the hard tap shank to self tighten. Or just go to an ER collet setup.

Just my fun for the morning. On the positive side, I did make some progress on a vise mount for an 8" Yost vise I picked up a while back.

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Old 09-07-2019, 02:24 PM
LKeithR's Avatar
LKeithR LKeithR is online now there a prize?
Join Date: Aug 2011
Location: Langley, B.C.
Posts: 5,260

Originally Posted by Don_S View Post
...I need to get a good ball bearing chuck suitable for power tapping...
I have a couple keyless chucks that I use for smaller drills but when it comes to larger stuff or tapping I always use a Jacobs 16N. For a 1" hole I'd be using a straight morse taper setup...

Measure twice and cut once...or...wait, was that the other way around?
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Old 09-07-2019, 02:43 PM
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greywynd greywynd is offline
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Join Date: Dec 2005
Location: Wainwright, Alberta
Posts: 5,265

I have a set of reduced shank drills that I reserve for use in the mill, I hold them with a collet. So far over the years I’ve never had one spin.

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Old 09-07-2019, 04:19 PM
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Join Date: Jul 2006
Location: Richmond, VA area
Posts: 12,111

AFIK, keyless chucks weren't intended for heavy-duty use. I had one cheapo on a Harbor Freight drill press that tightened up and I had a helluva time getting the drill out. They tend to self tighten, I believe.

Keyless chucks are for precision and convenience.
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Old 09-07-2019, 04:44 PM
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Ironman Ironman is offline
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Join Date: Feb 2008
Location: Warburg, Alberta, Canada
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Originally Posted by USMCPOP View Post
Keyless chucks are for precision and convenience.
Yes. Got one for the lathe tailstock, another light duty application. I have been told that chalk dust or baby powder on the taper will lock it in good. I tried it and so far I have not lost a chuck. I also have 3/4" ball bearing chuck for the gear head drillpress, but drilling with a 1" bit is best done with a morse taper.
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