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Drill Chuck Mounting Taper

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PHPaul

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#1
Are drill chuck mounting tapers standardized?

The chuck that came with my Grizzly mill is, frankly, junk. Just horrible. Gritty action, sloppy key fit, won't stay tight. It's mounted on a nice R8 collet tho.

What I'd like to do is buy a good chuck and mount it on my existing collet, but I need to know what I need to know (if that makes sense) before ordering one.
 

cathead

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#2
Yes, they are standardized. My guess would be that it is a JT3 (Jacob's taper#3) but it could be one of several others depending
on the size of the chuck. It's pressed on like a Morse taper. I have seen threaded on chucks also but that is much less likely.
What size chuck is it?

The JT3 is 1.22 inches long, .811 inch on the fat end and .7461 on the top.

As a point of interest, I just got a JT3-R8 adapter on E-bay for about 12 dollars made by a company called Bodee, and very
nicely crafted I must say. I got the dimensional information from Little Machine Shop.com where they have a bunch of
handy charts on all the common tapers, well worth looking at.

You will need to separate the drill chuck from the R-8 to know for sure what taper it is.
 

PHPaul

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#3
I already popped the chuck off, thinking to disassemble it and see if I could smooth it up. It's not apparent how it comes apart and I don't think there's much to be done with it anyway.

Thanks for the data, I'll measure it to be sure and then order a good chuck.
 

Liljoebrshooter

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#4
See if there is a number stamped on it somewhere. There is a bunch of different tapers. Screenshot_20181226-075130.png

They can be either way, 3JT or JT3, same taper.
 

PHPaul

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#5
It's a B16 taper, some Euro thing. Wonder what the odds are of finding a Jacobs chuck in that taper?
 

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Bob Korves

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#6
The piece that goes between the drill chuck and the spindle is called an "arbor." Here are the Jacobs taper arbor sizes, the most commonly found chuck mounting arbors sizes in the USA:
1545836969418.png
Edit: Some chucks mount semi permanently to the spindle, without an arbor adapter. The sizes of the taper that go in the chuck will still be the same.
 

Tozguy

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#7
My oem drill chuck came with a B16 taper. If i recall correctly the B16 taper is a shortened Morse taper.
I suggest that you get a new arbor with the new chuck. That way you can choose the chuck mounting taper that suits you best.
Once you have a new chuck, have ago at dismantelling the old one for educational purposes. I believe that you will be able to fix it.
 
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