# Drill Chuck Mounting Taper



## PHPaul (Dec 26, 2018)

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.


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## cathead (Dec 26, 2018)

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.


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## PHPaul (Dec 26, 2018)

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.


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## Liljoebrshooter (Dec 26, 2018)

See if there is a number stamped on it somewhere.  There is a bunch of different tapers.
	

		
			
		

		
	




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


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## PHPaul (Dec 26, 2018)

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 (Dec 26, 2018)

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:


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.


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## Tozguy (Dec 26, 2018)

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 a go at disassembling the old one for educational purposes. I believe that you will be able to fix it.


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## Tozguy (Dec 26, 2018)

This page has the scoop on machine tapers.
https://en.m.wikipedia.org/wiki/Machine_taper


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## NortonDommi (Dec 28, 2018)

You can buy chucks with a variety of Tapers, choose what you want to suit an arbor or get an arbor to suit the chuck you like.


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## whitmore (Dec 5, 2020)

Tozguy said:


> This page has the scoop on machine tapers.
> https://en.m.wikipedia.org/wiki/Machine_taper



And another web page breaks down the B tapers with angles and such
https://www.arceurotrade.co.uk/projects/Info/Drill-Chuck-Taper-Dimensions.html

Morse #2 and B16 and B18 and Jarno tapers are (almost exactly) the same angle, so if you
only want to set the compound or taper attachment up once, they play nice together.


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## Buffalo21 (Dec 5, 2020)

2 of my Rohm chucks are B16


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