View Full Version : Fitting a chuck to the tailstock, how?

DC Kelley
09-12-2006, 02:10 AM
I have obtained a common Jacobs chuck which I want to put in the tailstock of my Moseley Lathe.

The chuck came with an arbor that fits the head stock (8mm WW type) but my tail stock is a 0.300 straight (no-taper) hole that need to be at least 1.25 inches, preferably >3.5 inches long. How do other folks mount this type of chuck in the tailstock when your lathe does not accept WW collets in the tail? I certainly do not want to damage the tailstock or reduce it linearity at all.

My goal in all this is to do some precision drilling for re-pivoting, but I will also try the free hand pin vise and graver method hotly debated last week and try to compare.

DC Kelley
09-12-2006, 02:10 AM
I have obtained a common Jacobs chuck which I want to put in the tailstock of my Moseley Lathe.

The chuck came with an arbor that fits the head stock (8mm WW type) but my tail stock is a 0.300 straight (no-taper) hole that need to be at least 1.25 inches, preferably >3.5 inches long. How do other folks mount this type of chuck in the tailstock when your lathe does not accept WW collets in the tail? I certainly do not want to damage the tailstock or reduce it linearity at all.

My goal in all this is to do some precision drilling for re-pivoting, but I will also try the free hand pin vise and graver method hotly debated last week and try to compare.

David Robertson
09-12-2006, 02:37 AM

This is not an answer to your question... but.. an alternative. You can turn down some brass rod to fit in your tailstock and drill it out to fit the size of small bit you will be using... get a good tight fit on the shank of the bit. This will give you a bit with a "shank" to fit your tailstock. If the fit is tight enough, the friction will be sufficient to hold it.. if not.. a little Loctite.. but do not use the Loctite to make up for a sloppy fit... use that piece of brass for a bigger bit.

I am not real sure a "common Jacobs chuck" will suffice as a "precision drilling device"... especially if the holes are tiny... and especially if you do not know your tailstock and headstock are perfectly aligned.


DC Kelley
09-12-2006, 02:48 AM
I agree, and I think I could get also an arbor with an MS#1 end from a larger machine and turn that down too. But I would really like to still have the chuck so that I can mount a variety of tools in it. I want to keep away from a specific solution so that I can build my set of micro-machine abilities If I had a specific pivot that needed this done, I would use your method in a moment.

From the dialogs on this part of the forum, there seems to be a fair number of people that use the drill bit mounted in the tailstock method, so what have they done to solve this one?? Surely there is a supplier of such an arbor out there?

Mike Phelan
09-12-2006, 04:47 AM
I don't have that problem with the Unimat as the Jacobs screws into the tailstock barrel.

However, David's idea is far better for accuracy.

Jerry Kieffer
09-12-2006, 06:28 AM
You are up against a difficult situation that really has no practical solution with your existing equipment. I fought this same battle with my first jewelers lathe. It is one of the reasons I seldom ever use jewelers lathes any more even though all three of my current jewelers lathes have collet holding tailstocks.
The first problem is that the mounting arbor on a standard Jewelers lathe is not large or stable enough to accurately hold a drill Chuck. My solution was to machine a new ram that threaded dirctly and to the drill chuck. The next problem was that a typical Jacobs chuck is not very accurate as mentioned by David. To make a long story short I found the least painful way to deal with this problem was to sell the standard lathe and purchase one with a collet holding Tailstock. (If you must use a Jewelers lathe) If you wish to drill in your words a "Precision Hole" on a consistent basis you will need a drill holding tailstock that is properly aligned. While there are a million different ways to drill a hole there are very few that will drill straight,round and without taper. The most common way to check a hole for these qaulities is with a pin gage that will certianly answer your procedure curiosities.

Jerry Kieffer

DC Kelley
09-12-2006, 07:23 AM
Well I can not say I like what I am hearing on this :frown: Musing over my options..... I did a short web search for any supplier of 0.300 inch straight spindle stock and so far have not found any. I could still go the way of having a shop turn it down from a larger spindle on another machine, but this seems wasteful to me.

If I go that way David R suggests, I will end up with some blank 0.300 by ~3.5 inch stock that I fit my bits into (permanently) for each job. Beside losing my bits, I am worried that they will be sticking out at least half and inch and hence be off centered worse than the chuck. I do not see how I use this scheme to mount a center drill either, although I could hog out a .125 hole that same way.

I don't want to machine on the tail stock, I would rather grab another tail stock off ebay and experiment on that is it came to it. (I am already rather fond of the nice nickel finish on this old thing, let along the fact the parts are all matched).

Regarding the Jacobs chuck, which at present is likely tapped into the arbor that in turn fits to a WW collect. It seems to be out of round by about 0.20mm on the chuck face. I presume it will get slightly better if I really tap the arbor home. This of course would get worse as the drill bit length increases - hence my desire to mount it in the tail stock where I could rotate out any bias and then rely on my headstock to run much truer (how true I dont know, but without any lateral load is at least 10x better).

Now here is a dumb question. Is a Jacobs #1 taper in fact different from a Morse #1 taper? This rather vital bit of data is useful if I go the route of getting a tapered spindle off a milling machine to tun down to a straight 0.300 taper.

Ah, very cool, the mailman has just delivered my copy of The Modern Watchmakers Lathe and How to Use it (Perkins), perhaps that will give some other ideas on this dilemma....

David Robertson
09-12-2006, 07:41 AM

Morse and Jacobs tapers are different. See this site (http://en.wikipedia.org/wiki/Morse_taper) for a good discussion of the various "standard" tapers.

You might want to give further thought to the freehand method of center drilling... I think you are starting to see why it has appeal. The one thing that is certain is that a piece of rotating stock has a center of rotation. If you can find it you can drill it!! Holding the drill in a pin vise.. using the tailstock as a reference point to hold the back end of the pin vise on center will reduce many of the errors you might imagine are going to develop.

In my opinion it is far easier than trying to rig perfection into some equipment that is inherently imperfect.


DC Kelley
09-12-2006, 08:33 AM
I am certainly not opposed to learning to do this by hand (a new skill for me), but I want to reach a bit for the right jig so I am have repeatable operations. Thanks or the link about Morse vs Jacobs tapers, this has bugged me for years.

I see now that I can get a J1 taper on a 3/8" straight shaft from Albrecht for about 30 bucks (Part #70583 for any one else that is interested). I would have this turned down to by 0.075 and think it would do the job okay.

Larry Vanice
09-12-2006, 12:25 PM
I have made and sold many tailstock chuck arbors at various Marts over the years. I make them of 12L14 steel with either .300 inch or 8.0 mm diameters and long enough for any likely need. I put a threaded black plastic knob on one end and a 1 Jacobs taper on the other. The taper is done on a Hardinge precision lathe, with the arbor held in a .300 or 8 mm 5C collet. Then I mount a good quality German key-type 1/4 inch capacity drill chuck. I check the runout of the final product with a dial indicator. Holding a 1/8 inch rod, the runout is generally from .001 to .004 inch.

I have not been to a Mart for several years now, but I think I still have a few of the arbors with chucks left over.

By the way, back in the late 1950's, Marshall sold a long .300 diameter steel rod with a Peerless or Moseley collet holder machined on one end. They were less expensive than their collet-holding tailstock option, and a good solution for use in an older lathe. These collet holders are very rare, so they must have come out in the waning days of Marshall's lathe business.

09-13-2006, 06:26 PM
If your looking for stock of a certain diameter try using the keywords "drill rod". It should get you to tool steel stock of whatever diameter you want.

As far as the chuck on the tailstock goes, I made one from a Dremel chuck and a piece of steel turned as a tailstock runner. Threading on the lathe allows for more accurate centering of the chuck than threading with a die. Of course the chuck itself introduces some error. For the most part it makes a good hole, but using a guide helps. For a guide I usually drill a piece of brass to tightly fit the arbor, with a hole to fit the drill bit as an extension of the hole. Cut off and push on end of arbor, and the drill gets held centered for starting the cut. It also seems to reduce the number of broken bits.

Your tailstock should have a runner in it that has a tapered hole in the end of it (non-standard taper, I think). The runner allows the use of centers and such, and you should be able to make accessories to fit the taper that would allow you to mount them without making a runner for each one (like the mounted drill bits discussed in a previous post). I would mount the drill chuck on its own dedicated runner, as you seem to be contemplating, in the interest of reducing error.

09-14-2006, 03:21 AM
It's likely going to be more satisfying (precise)
to use a 2nd chuck, mounted on
a runner (or better yet...
tapered spade drills in the tailstock).

But if you *really* want to get double use
of that same chuck, you'll probably end up
mounting it on it's own runner, as previously
discussed. (the collet-holding tailstock is
a pricey option.) The simplest way would be
to remove the jacobs chuck from the WW arbor,
each time, and re-mount it on a runner with
the required jacobs taper.

If you have't yet solidly tapped the chuck and
the WW arbor together, separate them and drill
a hole right through the chuck (center drill,
etc.) so you can tap the WW arbor off with a
punch, whenever needed. (Tap the chuck off the
WW arbor, and then onto the runner.)

Re-separating them is almost effortless with that hole present.

I have the same setup, but will likely put
a different Jacobs chuck on a runner (does
someone have one in stock?? ;-) but this
will not be for high precision drilling.

DC Kelley
09-14-2006, 05:10 AM
Several good ideas here.

I have sent a PM to Larry Vanice, asking him about his .300 arbors This still strikes me as the best solution. The problem with a stock drill press shaft is it is not very long. Update: Larry is sending me one of his longer tail stock runners, So now I will have a rohm chuck set for either end of things and feel well equipped.

Smudgy: The bass plate you describe was called a “flag” when I grew up and you would make it with several of your common holes, each just over sized, and then clamp the flag up against the work piece to reduce any flex in the drill. Setting the drill bit deeper into the chuck does much the same thing. You need a cross slide to mount it on, or you can weld it up to a bit of rod and put it in your center rest.

I am not sure what the taper is on the points of the runner, but I would think mounting the (heavy) chuck in a an arbor fitted to that might not give much support and the shorter length means accuracy could be less. All in all, the simple approach to me still seems to be a nice long 0.300 center with the Jacobs taper on the end of it.

[And to be true to my sense of inquiry, once I get this solved I will post some “beginner” pics of the setup and the holes I get with it as well as the pin vise method for comparison.]

DC Kelley
09-30-2006, 06:18 AM
Larry has sent my one of his stocks and it is everything I could want. Run out is perhaps 0.002 but As I can easily rotate it this can be dialed out. I am quite content using the tip of a #000 pilot bit and this set-up to spot the center of holes. Will post a couple of pics. Getting comfortable with the graver is slower going for me. I have not yet got the hand of hitting the center, but I can certainly feel the wiggle when I am off center.

Rich McCarty
09-30-2006, 11:22 PM
If you're drilling an arbor to repivot then the accuracy of the hole isn't all that important. What is important is that the new pivot is concentric, so make the new pivot slightly oversize and turn it true after mounting it on the arbor. I'm lucky to have the repivoting/drilling attachments for my Lorch. After catching the center with a graver, I use straight flute carbide drills that are mounted (with loctite) on 4mm drill rod stock. After mounting the new pivot, I put the arbor between centers (the most accurate way of holding the work) and turn the new pivot true with the cross slide.

I don't believe that a collet holding tailstock is neccessary at all. I don't think they were ever made for the Geneva pattern lathes.

Don't forget that before the collet was invented in the mid 19th century all lathe work was done between centers - and this is still the most accurate way of turning.

Good Luck

10-13-2006, 06:05 PM
You know I'm just a DUFFER at machine work.
You KNOW I only got a lathe a few weeks ago.
BUT! Try it.
TRY IT! I was amazed. AMAZED.
I wasn't even using the lathe - just a drill press. I MADE an ersatz graver, chucked a piece of round stock in the drillpress; MAN! I was amazed. Under the CRUDEST of conditions that crude graver literally walked to the center.
DON'T take my word for it.
Try it and AMAZE yourself. You don't need a chuck holding tailstock - and I know NOTHING.

DC Kelley
10-14-2006, 02:09 AM
Catching the center is not as hard as I had first thought, but man I have much more respect for those that can hold a graver steady and turn things down to the right size. I still much prefer to "turn the cranks" to get things done. I think my current favorite method remains using the tip of a pilot bit in the tailstock chuch that Larry sent me to start things.

My latest acquisition was a used diamond wheel grinder (a Baldor clone for about 300) so now I can shape and polish my graver bits with ease. I really think you need the metal table to get the angles right at my (novice) skill level. I made a small wooden jig with 45 degree cuts and routed a slot for the graver sizes that I use. Holding the bit up to a grinder face freehand just caused multiple angle problems.