Thread: Jacobs Chuck Problem

Hi Willy.
I've got no answers but look on in interest. I have just ordered a chuck and bits and am about to make my first pepper mill, when the stuff arrives.
Any chance of you going through a blow by blow account of your process? Love to see some photo's when you get that matter sorted out.

Couple things maybe:

Make sure that there are no high spots been created from a spinning taper. Ya know what I mean... Same sort of thing that happens to a drill bit when it spins in the chuck - gets that burr that needs to be filed off. If the shaft and or taper are good quality I would say that this shouldn't be the problem.

Is there a lubricant of some sort on the taper and or in the shaft.

How about rust.

Is there any debris or "gunk" in the shaft that needs scraping out. A small chip of wood will cause this. Or pitch from wet wood that was able to get into the shaft.

A light sand with some fine worn out paper will clean the taper off well and or I stuff a small piece of rag or steel wool wetted (not soaked) with solvent down the shaft with the knockout bar to clean it out.

I've found there are times when I just need to give the drill chuck a good smack with a rubber mallet to seat it. I tend to hold the drill chuck so it's about 5mm from seating itself and then give it a firm hit and drive it home. That usually fixes if for me if everything else looks clean.

Hang on... are you saying the chuck body is undoing from the MT, or are you saying that when you back off the work the MT is falling out of the tailstock?

The former is easily fixed with a dab of loctite on the threads... and the latter, well it's a common problem with a few simple solutions:

1. What Toolin' has already mentioned.
2. Just grin and bear it. When backing off the bit, grab the jacob's in the left hand to hold it in position while winding the tailstock with the right. Obviously works best with the work spinning and the jacob's in the tailstock... unless you like grabbing spinning bits.
3. Drill and tap a hole in the small end of the MT to take a bit of endless thread. Inset into tailstock, so the endless thread protrudes near the handwheel, throw on a washer and wing-nut to hold all in position.

I seriously wouldn't go anywhere near it with a torch!

FWIW, I use #3 method when using the jacob's as pin-jaws in the headstock, but being inherently lazy I usually fall back to #2 method when simply drilling work out.

Nope, I have one like that too, it is not screwed into the chuck, the MT is a push fit on a short taper in the back of the chuck & it used to come lose on mine to.
I can't remember for sure but I think I gave it a good buffing with scotchbrite & a couple of wacks with a block of wood & it hasn't moved since.

Originally Posted by cedar n silky

Hi Willy.
I've got no answers but look on in interest. I have just ordered a chuck and bits and am about to make my first pepper mill, when the stuff arrives.
Any chance of you going through a blow by blow account of your process? Love to see some photo's when you get that matter sorted out.

Yep no problem just working it out and playing along the way the boring part is the only place I am having issues so far but will hope to have that all fixed in the morning I am trying two ways one with a 25mm auger bit and also the just using a sawtooth bit and extensions.

Thanks TA will check that and give it a try .

Ahh... a press-fit?

Toolin' still has the right idea, but I'd also colour the taper with black marker (or perhaps a fine chalk) then try refitting the chuck so the next time it comes adrift it could be scrutinised for a "wear pattern."

Sometimes they just don't fit quite right and need a touchup.

Yep Press Fit.

Its a real bugger will go down and have a play after dinner and get back to you guys.

I am also trialling two methods of doing the bore through, sawtooth and using a Auger bit.

Haven't tried the auger bit yet as it has me a bit worried as on the end it has a screw bit that could cause some issues, I am thinking it may pull the chuck out of the taper all together that would be real scary .

At least one thing is going right for me today, I finally made pea and ham soup and it tastes bloody fantastic.

Skew has a good point I wasn't seeing. Are you saying the body of the chuck is coming loose from the morse taper shaft. Then I'd give it a real good hit to seat the drill chuck body to the morse taper shaft. Had that happen a few times in the past and a real good smack with a heavy woodem mallet to seat the two together fixed it. I always wound the jaws so they were inside the body so as not to pound on them.

Originally Posted by WillyInBris

Yep Press Fit.

Its a real bugger will go down and have a play after dinner and get back to you guys.

I am also trialling two methods of doing the bore through, sawtooth and using a Auger bit.

Haven't tried the auger bit yet as it has me a bit worried as on the end it has a screw bit that could cause some issues, I am thinking it may pull the chuck out of the taper all together that would be real scary .
At least one thing is going right for me today, I finally made pea and ham soup and it tastes bloody fantastic.

Scary is not the word I would use.

Gently file the screw thread off.

Most augers with the thread are not meant to be used in power applications.

Hope you read this before you have to have the clothes and workshop sanitized.

Good news guys

I found that the inside of the chuck (sleeve cant think of a better word?) had grease in it where it meets the Morse taper shaft gave it a clean with some isopropalene and some toilet paper and gave it three whacks with my mallet and wella its one piece the chuck is also further up the shaft then it was and working fine.

Thanks again guys for ya help

Originally Posted by

Scary is not the word I would use.

Gently file the screw thread off.
Most augers with the thread are not meant to be used in power applications.
Hope you read this before you have to have the clothes and workshop sanitized.

Thanks ,

Na wasn't going to touch it until I got some recommendations on how to approach it, I used one years ago in a drill thought the thing was going to break my wrists .

This time I thought I would ask

So just file it to a point? Ill go get a small file in the morning.

Originally Posted by WillyInBris

Hi Guys,

OK you guys are aware I am working on some pepper mills any way I am having a bit of an issue boring them out .

Whats happening is the chuck is turning on the taper, the taper is holding fast on the tail-stock but when I start boring with the sawtooth bit and extension on and back it up a bit to clear the breach it comes loose off the taper

I have given the chuck a tap but to no avail, the only other thing I can think of is to heat the chuck with a torch tap the taper in and let it cool but am unsure if it create more problems then its worth.

PS the Jacobs chuck is a 13mm from Carbatec

This is how we fitted morse tapers to drill chucks when I was working in engineering shops.

Clean the tapered seat in the back of the chuck ,clean the tapered shaft .Wind the jaws of the chuck back into the body of the chuck so they dont protrude.
Place chuck in oven and heat it up to about 250 degs,place tapered shaft in your freezer for an hour or so.

When the chuck is nice and hot and the shaft cold place the chuck on a solid surface with the seat facing up .Drop the frozen shaft into the seat and give it a whack with a copper faced hammer.Let them cool off .I doubt you will ever get them apart again if you do it this way .

I'd strongly discourage whacking a Morse taper to ensure seating, especially in the headstock where such whacking could damage the bearings. Light whacking with a knockout bar is OK to dislodge it as there's pretty much no other way; on some MT sockets, there's an oval hole crosswise for placement of a wedge for removal, but I've never seen such an arrangement on a lathe.

After assuring that both the taper and the socket are clean and dry, vigourously push the taper in the socket with a twisting motion (called "wringing"). This should provide adequate purchase. Also, shallow plunges with frequent removal from the drilled hole to exhaust chips will reduce grabbing by the workpiece.

For removal from the tailstock, backwinding should suffice (at least it does on mine).

I've had better results in end grain with an auger bit than with a Forstner or Forstner-type. The auger under power isn't quite as scary in end grain, because screws in end grain are a terrible fastening anyway - behave more like a drill. I've found that the screw threads fill with wood dust and then behave about the same as if I'd ground off the threads. That said, make a test bore with a power drill in a sample of your timber held in a vise to help decide whether to grind off the threads; hardwoods don't behave the same as softwoods. Irwin have recently (within the past year AFAIK) introduced several sizes of auger bits which I like immensely. Worse comes to worst, grind the threads off one bit of each size, and leave another as is, depending of course on whether your arsenal demands both types.

Joe

Originally Posted by joe greiner

I'd strongly discourage whacking a Morse taper to ensure seating, especially in the headstock where such whacking could damage the bearings. Light whacking with a knockout bar is OK to dislodge it as there's pretty much no other way; on some MT sockets, there's an oval hole crosswise for placement of a wedge for removal, but I've never seen such an arrangement on a lathe.

After assuring that both the taper and the socket are clean and dry, vigourously push the taper in the socket with a twisting motion (called "wringing"). This should provide adequate purchase. Also, shallow plunges with frequent removal from the drilled hole to exhaust chips will reduce grabbing by the workpiece.

For removal from the tailstock, backwinding should suffice (at least it does on mine).

I've had better results in end grain with an auger bit than with a Forstner or Forstner-type. The auger under power isn't quite as scary in end grain, because screws in end grain are a terrible fastening anyway - behave more like a drill. I've found that the screw threads fill with wood dust and then behave about the same as if I'd ground off the threads. That said, make a test bore with a power drill in a sample of your timber held in a vise to help decide whether to grind off the threads; hardwoods don't behave the same as softwoods. Irwin have recently (within the past year AFAIK) introduced several sizes of auger bits which I like immensely. Worse comes to worst, grind the threads off one bit of each size, and leave another as is, depending of course on whether your arsenal demands both types.

Joe

I've got to be honest... No disrespect intended but... If your lathe can't handle the odd whack to the bearings like we've described then you better invest in a better lathe or at least upgrade the bearings to some made somewhere other than china.

I know what you say about wringing but there are many times when this just isn't near enough to seat a drill chuck. When everything is absolutley clean and new it works... A # 3 MT is far better but they're not available on most lathes - I don't think even the Stubby has one (mine does but I have a oneway).