View Full Version : Drill chuck on and off's?

A.K. Boomer
10-25-2006, 09:52 AM
I just ordered a couple arbors for my drill chuck, its a Jt 6 1/2" and i already had a R8 arbor, now I'll have a MT3/JT6 arbor (for rotary table) and a 5/8 straight shank to JT6 (for quick change Tool post), my question being is what do you guys use to take the chuck off one JT 6 and put it on the other without butchering anything? :confused: thanks.

J. R. Williams
10-25-2006, 10:08 AM
To remove the chuck use a pair of "Chuck removal wedges" They come in pairs and have the correct gap for the chuck and arbor. Any good supply catalog should show a photo of the set. You might have to drill the internal back of the chuck and use a punch if the arbor does not have a shoulder for the wedges. Another option is to drill the arbor for a cross pin so the wedges will work.


10-25-2006, 10:08 AM
They make wedges for the press fit chucks - different set for each taper. Check out use-enco.com, search on drill chuck wedge

A.K. Boomer
10-25-2006, 10:08 AM
Sorry for thinking outloud before a reply but why wouldnt they use the leverage of the chuck itself (be it keyless or not) to "self pry" itself off of the arbor in the fully extended opening mode? if not that do you think it worthwhile to bore and tap a hole directly in the center of the chuck so an allen bolt can be inserted through the chuck opening?

10-25-2006, 10:11 AM
Order a set of Jacobs wedges. Or, you can sometimes use a pair of hardened dowels to persuade the two apart. And on some chucks the center can be drilled-n-tapped to put a screw in for pressing out the arbor.

But this is not something you want to do on a regular basis as a normal mode of operation.

10-25-2006, 10:31 AM
The allen bolt through a tapped hole in the chuck is the method to use in removing a Jacobs chuck from it's arbor when the wedges don't work or can't be used.

BadDog is correct however, the installation of a chuck on a JT is considered semi permanent and the intent is not to swap adaptors on a regular basis.

Forrest Addy
10-25-2006, 10:36 AM
You don't. You mount them on the Jacobs taper and leave them. If you need to istall a chuck in an R-8 taper you get another chuck.

Jacobs tapers were intented for semi-permanent mounts. If you try to mix and match among several shanks you wind up with spinners and drop offs.

10-25-2006, 10:56 AM
Ditto on what Forrest said. If you try to go swapping them around, you'll just begging for problems.

If you want to use a drill chuck in multiple places, you may be able to use a straight shank. For instance, use your 5/8" straight shank in a 5/8" collet on your milling machine. You don't need the R8 adapter.

10-25-2006, 11:47 AM
Yeah....once them JT6's are banged in its almost impossible to separate them...wedges or no wedges ...without damaging something or buggering it up.

you will have to knock so hard on the wedges ...that they will indent what ever they come up against.

I've read about people cooling down the arbor and heating up the chuck ...and in conjunction with the wedges... though ...they still had themselves a difficult job on .

all the best..mark

Paul Alciatore
10-25-2006, 01:26 PM
Expanding just a bit further on what Forrest said, in the past several years I have acquired a bit of a collection of drill chucks. I have about 4 or 5 that have adapters for my SB tailstock and even one with a taper for the headstock (handy for drilling work mounted on the cross slide). It is very handy to change chucks instead of tools in the chuck. It can save a lot of time when you are making multiple parts. In addition I have two for the mill/drill, two for my Unimat and a couple that I have not even put an adapter on yet. They are handy for some hand work. I frequently mount a countersink or drill in them for deburring and other work. Good for cleaning out a hole with a reamer also.

I look for sales and buy them as they become available. A couple of times I purchased two at a time when the price was right.

In short, use your money to buy chucks, not adapters and wedges. You will have a lot more versatility in the end. And you won't have problems from damaged Jacobs tapers.

10-25-2006, 04:36 PM
I would certainly concur that they were not intended to be regularly disassembled at "that end". It has to be a great opportunity to ding something up. I have an arbor with only a small ding...and darned if that thing will never run true.

Several have mentioned the removal wedges. These are ordered in a specific Jacobs taper as they have a notch just big enough for the taper...and should be used that way. I had intentions of getting some in say J-3 as they would be "big enough" for other tapers, but that is a bad idea. I borrowed several sizes in the end and figured out just why they are made to fit.

To save you some grief...as some mentioned to me when I asked about removing my Jacobs *keyless* chuck from a taper here a while back-- DO ****NOT**** center drill a *keyless* chuck. You will ruin it. Interestingly, however, for a regular keyed chuck, Jacobs even mentioned the "center drill followed by the center punch" solution on their web site. Apparently, the buggers are case hardenend such that the center is still relatively soft.


10-25-2006, 05:10 PM
Yeah I removed one a few years back, to permit swapping the better of two chucks from a MT to a straight arbor. The wedges didn't work. Heating/cooling didn't work. Had to do the drill hole in back and punch it out AFTER heating chuck and cooling arbor. Found it had been loctited in.

But after that experience I view the mounting not as semi-permanent, but ABSOLUTELY permanent. ...as in "til hell freezes over". :D ...or at least til the arbor gets damaged beyond use for some reason. That's the only reason I'll remove another.

A.K. Boomer
10-25-2006, 10:51 PM
Damn,,, thanks for the advise everyone, sounds like im going to use the 5/8" and that will do most things i need it for, eventually i will get more chucks so i never have to remove, I really didnt think it was going to be an issue for them losing thier grip after awhile, there must be slight material loss each time or buring, so much for my frugal attemp at being cheap...:(

A.K. Boomer
10-25-2006, 11:15 PM
Last but not least --- what do you guys do when you put one on? do you just press it on with the load from the mill handle or do you apply more force or impact with peices of wood inbetween or what? thanks...

10-26-2006, 10:42 AM
I'd go easy on using the mill as any sort of arbor press:D

I've had my Bridgeport all apart and there isn't much in the way of teeth in the back of the quill....and if you break them, it is pretty much catastrophic....your quill is toast and is hand lapped to the bore.

I was tought to whack the back of the arbor with a hammer (I use brass) while holding the chuck in your hand to seat it. You won't apply too much force that way while still getting the job done.

I read, however, somewhere else that the right way was to push it in the back of the chuck and then drop it arbor end down (using the weight of the chuck) onto the top of your vise or an anvil etc. I would imagine this would also help put a lid on the maximum force used to seat it (determined by the weight of the chuck).


A.K. Boomer
10-26-2006, 10:51 AM
PT what do they have in the center of the keyless chuck that gets in the way when your drilling them? Is there a horizontal pin or something?

10-26-2006, 11:52 AM
There is acutally a screw down the middle of the body of a the Jacobs style keyless chucks that actuates the whole works. Since these look very similar to the Albrecht and others of the same design, I will assume they are internally similar.

You will note that these arbor-type keyless chucks are longer than a standard keyed chuck and that is because of the mechanism in behind the jaws. They are not just a keyed chuck with some handles as it turns out.

I always wondered how they could be adequate to grip a drill after hand tightening. You can't just take a keyed chuck and twist it by hand and get that sort of force. There is a mechanical advantage in their use of the screw to push the two halves of the chuck away from one another, tightening the jaws. However, the Jacobs model I have has some special "wrench flats" of sorts. Their literature indicates that you can get substantially more gripping force when needed by even gently tightening it with this wrench.


A.K. Boomer
10-26-2006, 07:53 PM
Hmmm, i have a generic one, i cant see any screw in the chuck jaw end of the chuck, but the chuck is now mounted to the R/8 arbor so i cant see from that side, wich side was yours located?, if i get mine removed and dont see a screw in either side do you think i would be safe to drill?

Paul Alciatore
10-27-2006, 02:22 AM
A little bit more on assembling chucks to the Jacobs tapers. The exact technique used should be chosen with consideration for the details of the situation.

First, Locktite should not be needed unless there is damage to one or both genders of the taper. If that is the case, some carefull repair work may be called for. Try to remove only the burr and not any of the surrounding metal. A Dremel or a small (1/8" diameter) round file could help here on the male taper. A female taper could be more challenging to clean up. Perhaps some spot work with a custom ground tool (from an old drill or whatever). Or the tip of a small grinding tool in the Dremel. Again, remove only the burr and not any surrounding metal. The burrs can be ground or filed to a level slightly below the original surface if the surrounding metal is not removed and this small "pit" will not alter the original fit.

If you are attaching the chuck to a MT or other taper adapter, then you can use a bit of force with a press, a hammer, or the weight of the chuck. If you are using a hammer, use a small one. Perhaps four or six ounce. RETRACT the jaws completely into the shell so you are not applying the force on the jaws. This is extra important if you are using a hammer. Perhaps the best way of applying the force is by banging the opposite end of the taper adapter on a soft wood surface with the chuck on top. This allows the weight/momentum of the chuck to seat it. If you use a hammer or a press, place wood scraps on both ends to prevent damage to the taper and the chuck. Do not hit it as hard as you can with a hammer as several lighter blows will probably seat it better and have less chance of causing damage than one hard one would.

Some drill presses have a Jacobs taper built in to the spindle and it is difficult to remove it for installing a chuck. In these cases, more discretion may be needed as hammer blows or excessive pressure could damage the down feed gear teeth and/or the spindle bearings. On my little $50 bench drill press I simply placed a block of pine under the chuck (with the jaws retracted of course) and with the down feed held in mid range by hand, I hit it a few times from below. There was some shock to the gear teeth of the down feed and the bearings, but as it was free to move up, that was not too severe. I was taking a chance of breaking the teeth or damaging the bearings, but it was only a $50 machine and over 10 years old so I felt it was an acceptable risk. On a more expensive one with a non-removable Jacobs taper, I would probably place a block of wood on the table and use MODERATE pressure via the down feed mechanism (again with the jaws completely retracted). If this did not work, I would disassemble the quill for the chuck installation and proceed as above with a standard taper adapter. But most higher priced machines will have a removable taper for tooling.

With a hand drill, you may have no choice except to put a piece of wood over the chuck and use a hammer to tap it on. In these cases, use as little force as necessary to get it to seat. But be sure it is seated.

10-27-2006, 11:57 AM
Regarding the keyless chuck-- I didn't mean to imply that there was a machine screw with a head you could see, but rather that it used a sort of lead screw arrangement with the lead screw being in the center of the chuck to drive the jaws forward thereby closing them. This screw arrangement is behind the jaws and is likely not visible without disassembly. I don't have mine in front of me and it was several months since I disassembled it, but I don't remember that you can see *anything* without disassembly. You can typically unscrew the conical portion of the nose of the chuck to see and remove the jaws. A standard *keyed* chuck has "threads" on the outside of these jaws instead of the lead screw that pushes them forward from behind as in the keyless chuck. In order to see the mechanism I was discussing, you have to remove the clamping screw and pull the knurled grip "collar" at the top of the chuck. I did this on mine as I bought it used and wanted to clean and lube the screw.

Mine looks roughly like this chuck, but is a slightly older model with wrench flats instead of a pin-wrench hole:


In short, it is probably "not" safe to drill down the center.

BTW--Here is Jacobs answer to arbor installation: http://www.jacobschuck.com/pdf/s1.pdf