JT1 chuck becomes loose all the time - any remedy?

How did you remount the chuck? Just twisted it on or did you drive it on with a "whack" of a soft-face hammer, etc?

The way we do it here, and they NEVER come off, is to clean it with something like you did, then retract the chuck jaws and whack it on with a rubber mallet quite hard... If you don't have a rubber mallet, you can put wood between the hammer and the chuck face.

Don't be afraid to hit it hard as long as you hit it straight on... But tehn again, don't hit it so hard that you bend the spindle either.

Send me your e-mail address and I'll shoot you a PDF showing the steps if needed.

Hi Joe, yes, I did just twist it on, counter-clockwise (against the rotation of the spindle) while pushing up. I do have a rubber mallet and will definitely try the technique you describe. I would probably try to wait until everything else fails because, as you say: "they NEVER come off". I still have an idea (which may be a delusion - we'll see) that I'll be able to find a chuck that's slightly larger that 1/4". Every so often (too often not to notice) I need to drill one or two steps larger than 1/4" in a soft material like ABS plastic which should be OK for the motor but larger than the current chuck can handle. So, if I find one, I would like to be able to make the old one to come off. Thanks for your suggestion!

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With a wedge set, you will be able to get it off.

By "never" I mean that ours never come off unless they have to... Our drills are often used in a production atmosphere, sometimes 24/7. A chuck falling off could cost a customer more than my drill...

Whack it on. It's the right way to mount it. Just don't bend that spindle, etc.

Make a press block you can put on the bed, and use the spindle to set the taper more firmly. JR Dweller in the cellar

DA wrote:

If you have blue spotting dye or artist's Prussian blue pigment, wipe a tiny amount on the arbor and twist the chuck gently onto it. Then examine the female taper under strong lighting. I will almost guarantee the tapers do not matcvh, and you will get a thin blue line at either end of the taper, where it is touching only at a narrow ring instead of the full length of the taper. Of course, you need a "master" to check against to find out whether the arbor or the chuck is the part made wrong.

If you don't have such dye around, you can use a magic marker or Sanford Sharpie, and see where the dye was rubbed off the arbor.

Jon

:

He means "never come off until you intentionally remove it". You can remove it using a set of Jacobs chuck removal forks for the size taper in question (JT-1). So -- you are not stuck with the chuck forever, you just don't have to worry about it coming off when you don't want it to.

BTW Try to avoid chatter when drilling, as it can make it more likely that the taper will release. One trick is to bring the bit into contact with the workpiece and apply moderate force before turning on the spindle, so it starts well engaged. And be sure that the speed is reasonable for the bit diameter too.

It also helps to clamp down the workpiece -- either clamp to the table or mount in a vise which adds a lot of mass to the workpiece so it can't vibrate around on the table.

As for checking the taper -- do you have any spotting blue? (Not layout blue, but what is used for scraping to a precise fit.) Put a very thin layer on the spindle taper, put the chuck on and lightly twist, and then remove. Look for patterns of where the blue transfers and where it is not bothered. If there is transfer at one end, and no transfer at the other end, it suggests that the chuck and the spindle have different tapers. Note that there is a European taper as well as the Jacobs taper -- and I don't know how different they may be.

But your bluing may show an area which is raised (by a ding) which prevents full contact. That you would want to dress with a hard Arkansas stone so the transfer of bluing is even around the spindle.

Get a reduced shank drill bit with a 1/4" shank. I've had a

5/16" one since about 1961 or so. The larger ones (1/2" to 1" with a 1/2" shank are called "Silver & Demming drills". I don't know whether there is any name other than reduced shank for the 1/4" ones.

Get the "pickle forks" made by Jacobs -- a pair of wedges in U form which are pressed on from opposite directions to pop the chuck off the taper. I have four sets in different sizes, and some intermediate sizes use a mix of forks from two sets to get the right sizes.

As for the soft hammer -- yes that is the way to do it. When mounting a drill chuck on a Morse Taper shank, I clean both surfaces, put a piece of 2x4 on a concrete surface, and hit it with the Morse taper end, letting the mass of the chuck seat it firmly. (Then, you only need to get the Morse taper mounted firmly in the drill spindle. :-)

Good Luck, DoN.

use-enco.com , has arbors , low cost , i like them .

I have many of their Taiwan keyless chucks ,

last long time .

Back in the days when a JT6-MT3 arbor cost $250 !

H'F' small bench drill press i got in 2003 , had a PSC motor .

I took it back , no power , Needs a CSR motor .

just got my 7th lathe , 7 by 10 . When they're almost free , why not $320 plus 7% ....

Nylon gears are bone dry . moly or graphite grease . Wont start ? Turn speed control all the way ,, til it clicks off , then try again .

I hate the motor adjust . i made 2 wood wedges . then i steel shim those wood wedges . I put ballbearings on lead screw ,

i drill one hole , far side of compound to reach far side swivel screw , near side swivel screw , i slot the side of cmpnd ( remove the plastic angle indicator ) to fit a tiny 12point box wrench in , then drop wrench onto a 12point , 1/4-20 screw .

cross slide wheel goes into a block/bearing . i flip it over and grind off the offending shoulder to allow more travel . flip it back to resell lathe .

far side carriage . i use one 6mm-1mm bolts as a pinch bolt to lock carriage . Toss the stupid set screws . they are supposed to help you adjust the far side "block-slide"

You need adjust far , but not near side . cause near side pushes down , dont need block slides , except in case of chatter .

This is how we did them for production machinery.::: Clean both the external taper on the arbour and the internal taper in the chuck . Place the arbour in the freezer for a couple of hours . Heat the chuck in the kitchen oven to around 180-200 for an hour or so, witht he jaws retracted into the main body of the chuck

Remove chuck from oven ,and place on a heat proof surface . Remove arbour from freezer and place in the back of the chuck , give the arbour a tap with a soft face hammer .Let both pieces normalise and they will never come apart .

That works well for Morse Tapers, and probably would be fine on the JT1 he has... But for some of the larger Jacobs Taper units, it doesn't provide a great option to set the chuck on... Most smaller drill presses hardly make

150# of thrust when hanging on the arm.