Drill chuck question

[Mike Walsh]

I have a 3/4" Supreme 9T3 drill chuck that I'd like to use on a Rikon lathe. From what I can find online, the chuck has #3 (Jacobs?) taper and I know my tailstock is a Morse 2. I got a Grizzly MT2/JT3 adapter from Amazon - I tried it quickly last night and the chuck side won't "catch", seems like it's bottoming out in the chuck. Does this make any sense?

Thanks,
Mike

[Paul Williams]

Yes the tang on the chuck is probably too long for the adapter. If it is a small amount you could grind it back. However, if your adapter relies on a tapered key to drive the chuck out of the adapter you would loose that function if you grind away too much, I'm visualizing that your set up is quite long and you are giving up a lot of space along the bed. Can you change the MT 3 to a MT 2 on the chuck itself? Seems to me most chucks can be removed from the tapered piece.

[Leo Van Der Loo]

I have a 3/4" Supreme 9T3 drill chuck that I'd like to use on a Rikon lathe. From what I can find online, the chuck has #3 (Jacobs?) taper and I know my tailstock is a Morse 2. I got a Grizzly MT2/JT3 adapter from Amazon - I tried it quickly last night and the chuck side won't "catch", seems like it's bottoming out in the chuck. Does this make any sense?

Thanks,
Mike

Did you blacken the opening in the chuck bottom and sides, to see if the arbor was bottoming out ??, and if so I would get another arbor rather than starting to grind on it.

However if you decide to grind the JT slightly shorter, you might find that the taper is not right, who is going to take back a worked-on adaptor, but there is a chance that the arbor then fits your chuck, want to take chances ??

[Mike Walsh]

thanks for the quick replies. The chuck just has the "female" taper, and I did not try blackening the opening - will do that tonight

[Ronald Blue]

Can you measure the hole ID at the top of the chuck with calipers and compare it to the arbor OD? Then if you can compare the depth of the chuck to the length of the arbor. Is it remotely close to getting tight? If you think it's close and just needs a little length removed go for it. Here is the table below with the Jacobs taper dimensions.

Taper	Large End	Small End	Length	Taper/ Foot	Taper/ Inch	Angle From Center
#0	0.2500	0.2284	0.44	.5915	.0493	1.4117
#1	0.3840	0.3334	0.66	.9251	.0771	2.2074
#2	0.5590	0.4876	0.88	.9786	.0816	2.3350
#2 Short	0.5488	0.4876	0.75	.9786	.0816	2.3350
#3	0.8110	0.7461	1.22	.6390	.0532	1.5251
#4	1.1240	1.0372	1.66	.6289	.0524	1.5009
#5	1.4130	1.3161	1.88	.6201	.0517	1.4801
#6	0.6760	0.6241	1.00	.6229	.0519	1.4868
#33	0.6240	0.5605	1.00	.7619	.0635	1.8184

[Marvin Hasenak]

Unless you have a reason tp keep the 3MT arbor, I would switch it out to a #2MT arbor. Just guessing but I believe the arbor that is in there now is a #3JT that fits the chuck, you should see the JT marking on the side of the chuck. Order a new arbor with #3 JT on one end and a #2 MT on the other. Remove and replace.

[Ronald Blue]

Unless you have a reason tp keep the 3MT arbor, I would switch it out to a #2MT arbor. Just guessing but I believe the arbor that is in there now is a #3JT that fits the chuck, you should see the JT marking on the side of the chuck. Order a new arbor with #3 JT on one end and a #2 MT on the other. Remove and replace.

He purchased a JT3 to MT2 arbor. "I got a Grizzly MT2/JT3 adapter from Amazon"

[Brice Rogers]

I bought a Harbor Fright MT2 drill chuck. I don't remember the exact price but it was under $15. It seems to work adequate for my uses.

[Doug Rasmussen]

.................................................. - I tried it quickly last night and the chuck side won't "catch", seems like it's bottoming out in the chuck. Does this make any sense?

Thanks,
Mike

No, it doesn't make any sense.

Is the taper in the chuck clean and smooth? If it is, can you try to tap the arbor with a soft mallet to see if it'll "catch", Jacobs tapers don't always catch as easily as a Morse taper.

Was this a used chuck? In my experience, many times the taper in used chucks are scored or otherwise damaged which is why they're being sold.

BTW, that's a large chuck and with a minimum capacity of 3/16" you may be limiting yourself from using small drills.

[Leo Van Der Loo]

No, it doesn't make any sense.

Is the taper in the chuck clean and smooth? If it is, can you try to tap the arbor with a soft mallet to see if it'll "catch", Jacobs tapers don't always catch as easily as a Morse taper.

Was this a used chuck? In my experience, many times the taper in used chucks are scored or otherwise damaged which is why they're being sold.

BTW, that's a large chuck and with a minimum capacity of 3/16" you may be limiting yourself from using small drills.

I think it does make sense, the OP has removed the MT3 arbor from the chuck it came with, bought an (Chinese made) arbor with MT2 and JT3, and tried to fit it into his chuck.

And as he said it does not catch, as in getting tight in the chuck’s female JT opening, after which you would use a malled to drive it in tight.

So he assumes that it is bottoming out in the chuck, which is quite possible, to make sure of that, I suggested he blacken the female opening and fit the arbor in, with a twist and then taken it out, he should be able to see where the arbor is rubbing.

If it is made too small it will hit the bottom, if it rubs somewhere on the wall, it has the wrong taper on it.

There are short JT 2, but since it had a JT3 installed in there, I doubt that very much, probably just chinese quality on the arbor he bought, but we shall hear I think.

[Doug Rasmussen]

I think it does make sense, the OP has removed the MT3 arbor from the chuck it came with, bought an (Chinese made) arbor with MT2 and JT3, and tried to fit it into his chuck.

And as he said it does not catch, as in getting tight in the chuck’s female JT opening, after which you would use a malled to drive it in tight.

So he assumes that it is bottoming out in the chuck, which is quite possible, to make sure of that, I suggested he blacken the female opening and fit the arbor in, with a twist and then taken it out, he should be able to see where the arbor is rubbing.

If it is made too small it will hit the bottom, if it rubs somewhere on the wall, it has the wrong taper on it.

There are short JT 2, but since it had a JT3 installed in there, I doubt that very much, probably just chinese quality on the arbor he bought, but we shall hear I think.

Leo,I don't see the mention of the OP removing a MT3 taper arbor from the chuck. If that's the case he should be able to do a comparison between that and the new one.

I'm no fan of Chinese goods, but I have yet to see a chuck arbor that far off.

Using a mallet to seat a chuck onto an arbor is a recommended technique by Jacobs. Of course, if it's not at all tight in the female JT3 a mallet won't help.

[Leo Van Der Loo]

Leo,I don't see the mention of the OP removing a MT3 taper arbor from the chuck. If that's the case he should be able to do a comparison between that and the new one.

I'm no fan of Chinese goods, but I have yet to see a chuck arbor that far off.

Using a mallet to seat a chuck onto an arbor is a recommended technique by Jacobs. Of course, if it's not at all tight in the female JT3 a mallet won't help.

Doug maybe I should go to bed earlier, I read he had a #3 taper in it, reading it again that was a #3 JT, so I’m bad

Hitting a chuck taper in with a mallet/hammer even, I learned a long time ago, and yes you are right of people being able to wrestle a drill chuck off of a taper and scoring the taper, as matter of fact I have one of my Jacobs chucks that I got for free after someone did that and could not keep the chuck on, I took it home and scraped the taper clean and I have had and used that for years, a nice 0-1/2” Jacobs chuck.

I have seen some turned rather than ground tapers to be used in the tailstock, thinner than they should be and the tailstock ram having to be out an inch or better or the taper would run into the ejector and wasn’t seated, it does take but a hair for tapers to go in farther, and with a chuck there’s very little extra room or you bottom out.

[Doug Rasmussen]

Leo, I've had taper mount chucks that wouldn't stay on. One was on a drill press where both the female and male JT's were buggered up. In that case we drilled through the chuck body and tapped the end of the drill press spindle so we had a bolt "locking" the chuck on. I've noticed a good many of the reversible power hand drills secure their chucks on with a bolt.

I've seen other cases where a loose chuck was loctite'd on. Even one or two that were welded on.

[Dane Riley]

I've seen this on a MT3 to MT2 adapter that would not accommodate the ejection tang. There does not seem to be a standard for tang length. I have no idea if this has any relevance to the original question.

[Mike Walsh]

Thanks for all of the comments. I checked the adapter and found the JT3 end is about 1/8" too long for the chuck. I'm trying to find a different adapter with a shorter JT3 length - if that fails I'll try grinding the end of the one I have