Thread: Chucking options for Rockler mandrels?

I would drill and tap a block of wood so that it fits the thread of your lathe. Then make a "chuck/mandrel" like the Penn State bottle stopper chuck. Since yours will be made out of wood, be careful with it, it will wear out with use.

bottle.jpg
On side "A" is your tapped threads to fit your lathe spindle. On side "B" you have to drill and tap for the threads that are on the pizza cutter, 5/16-18. Cut a piece of 5/16-18 All Thread about 2 inches long. Screw that into your tapped hole. You will probably have to make several before you get one that runs true enough.

Here is the Penn State Bottle Stopper mandrel, check how it works to getthe idea of how it all flows together. Bottle Stopper Chuck 1 in. x 8tpi at Penn State Industries

Vemec sold ER25 & ER32 Collet Chucks which they made specifically for wood turners. After my last recommendation I checked with Enzo as they no longer carry them as a standard item, but will make a collet body on request.

The Vermec made collet body is very good and can be machined to suit your lathe spindle as M30 or 1" x 8 tpi etc as it is very similar to their excellent spindle adaptors. The collet nuts and collets are a standard engineering line and can be purchased individually or as sets online.

Using a standard MT1 or MT2 Jacobs Chuck without tail stock support or without a drawbar is risky. Just recently there was an injury at an event I attended where the turner was injured by a jacobs chuck as the MT2 was "auto ejected" by the tailstock quill while drilling on the lathe.

I found it easy to make a drawbar to suit a jacobs chuck .My jacobs chuck had a dimple in the morse taper end and it was easy to drill a hole in the end and tap it to suit a bit of allthread which then went through the headstock . Add a washer and a wingnut and your jacobs chuck is secure .
Ted

Originally Posted by Mobyturns

Vemec sold ER25 & ER32 Collet Chucks which they made specifically for wood turners. After my last recommendation I checked with Enzo as they no longer carry them as a standard item, but will make a collet body on request.

It hadn't occurred to me to use a collet chuck, but that would solve the problem. Even better is that I have a full ER32 set for my milling machine, although the body is on an R8 taper. A quick search suggests that an MT2 body is not expensive. I was a bit worried about running a drawbar through the headstock, but the more I think about it the less reason I can see why it should cause any problems, as long as there's enough flat space in the handwheel for a washer and nut.....

Originally Posted by turnerted

I found it easy to make a drawbar to suit a jacobs chuck .My jacobs chuck had a dimple in the morse taper end and it was easy to drill a hole in the end and tap it to suit a bit of allthread which then went through the headstock . Add a washer and a wingnut and your jacobs chuck is secure .
Ted

Good to know that running a drawbar through the headstock doesn't cause any problems! For some reason I was nervous about doing it, possibly because the nice shiny handwheel doesn't look like it was intended to have nuts tightened on it!

Unfortunately the Jacobs chuck (sold for woodwork but I can't remember which store I got it from) on my lathe has an MT2 taper on the lathe end of the stub, but the chuck itself is held to the other end of the stub with another taper. I know this because it was delivered with the chuck not fitted to the stub! The result is that a retrofit drawbar wouldn't solve the problem for my chuck, although it would if the chuck screwed to the stub! I could of course use the usual fixes of freezing the shaft and applying a suitable Loctite to keep the chuck on the stub, but it would still be a physically unsupported taper... and I don't really want to weld it!

Warb, the collet chuck that Mobyturns is talking about, screws directly on to the lathe shaft, so there is no need for a drawbar.

This is the set sold by Vicmarc.

Lathe Accessories: Collet Set

Originally Posted by Warb

Unfortunately the Jacobs chuck (sold for woodwork but I can't remember which store I got it from) on my lathe has an MT2 taper on the lathe end of the stub, but the chuck itself is held to the other end of the stub with another taper.

The other taper is a Jacobs taper.

Originally Posted by DJ’s Timber

Warb, the collet chuck that Mobyturns is talking about, screws directly on to the lathe shaft, so there is no need for a drawbar.

I did notice that, and the PSI Jacobs chuck does the same thing. However from experience anything that is made to order tends to be quite expensive - Vermec no longer list them as a stock item, as Mobyturns said - and as I already have a collet set I was just looking at prices for a chuck to suit! The set you linked to is no longer available, and previously was $170. A Chinese MT2 collet body on eBay is $30 delivered, and if using a drawbar through the headstock is OK (and the more I read, the more it seems to be regarded as such), then that looks like a very inexpensive way to avoid buying another set of collets.... Much as I try to follow the "buy the best, cry once" philosophy, I'm not sure that I'll be using those mandrels enough to justify spending too much!!

Originally Posted by Colin62

The other taper is a Jacobs taper.

I didn't know what it was called, though it is clearly not Morse because the angle is wrong! I'm assuming it's still not wise to load it sideways (lathe use) without any inwards pressure?

Originally Posted by Warb

I didn't know what it was called, though it is clearly not Morse because the angle is wrong! I'm assuming it's still not wise to load it sideways (lathe use) without any inwards pressure?

Jacobs chucks were designed for use in drill presses which have a constant force applied to both the MT2 and Jacobs tapers in normal use. Some drill presses have a slot milled in the shaft to permit the MT2 to be ejected with a taper pin if the compression forces jamb it in tight.

The problem's using Jacobs Chucks (without drawbars) in a wood lathes head stock without tail stock support is that,

1. wood compresses - so loads applied at 90 degrees to the lathe axis can cause the work piece to loosen in the Jacobs Chuck. (note the small bearing surface that supports the work piece in the chuck.)
2. certain plunge style or taper cuts with the skew or a detail gouge may act as a "screw" to apply an axial force that loosens the MT2 interface, or the Jacobs taper interface.
3. catches exacerbate #2

Both mean that the chuck, work piece or both may become unstable with potential for catches, UFO's etc.

Originally Posted by Warb

Good to know that running a drawbar through the headstock doesn't cause any problems! For some reason I was nervous about doing it, possibly because the nice shiny handwheel doesn't look like it was intended to have nuts tightened on it!

If it was me I wouldn't be making this any more complicated than it needs to be...

I presume that you have at least one scroll chuck. If so, remove the jaws and clamp a threaded rod into the jaw slides of the same diameter and thread count as the thread screw on the pizza cutter. Most scroll chucks close to a smaller diameter when the jaws are removed.

Install the threaded insert supplied with the pizza cutter as per their instructions. You are going to have to do that anyway.

Screw a piece of sacrificial wood onto the threaded rod hard up against the chuck body to save the chuck from tool contact and maybe to also provide a diameter mark for marry up with the pizza cutter.

Screw the handle blank with supplied insert onto the threaded rod held in the scroll chuck.

Turn and almost finish with tailstock in place. Back off the tailstock and finish handle end.

Nothing more than a short piece of threaded rod required!


If you don't have a scroll chuck you will have to get a bit more complicated.

On using a drawbar to hold your MT in the headstock.... putting a nice shiny washer next to the nice shiny hand wheel should allow you to tighten the nut without spoiling your nice shiny hand wheel...

Like TurnerTed, I've also managed tap some of my MT2s to take a drawbar. It's not difficult to do.

Unless you are getting very heavy handed, CAs (like loctite) will hold a surprising amount of tension. I have chucks mounted on revolving centres attached to MTs that have held good in tests up to 30Kg of tension.

However, a collet body that screws directly onto your spindle thread would be much more convenient than MT and drawbar if you think that you are going to be doing a lot of collet work on your wood lathe. Few of us do.

Originally Posted by NeilS

....... remove the jaws and clamp a threaded rod into the jaw slides of the same diameter and thread count as the thread screw on the pizza cutter. Most scroll chucks close to a smaller diameter when the jaws are removed.

This is the bit I was dubious about. I've already made a few of these pizza cutters, and already have the mandrel in a Jacobs chuck. What I've never been "brave" enough to do is to chuck that mandrel directly in the scroll chuck on the lathe. All the metal working chucks I've used have been (seemed?) much lower geared than the chuck on my wood lathe, and clearly designed to clamp on steel. The reason I've never put the mandrel directly in the wood lathe chuck is that I've never been convinced that doing so would be both safe (clamping pressure and area) and would not damage the chuck. The slides on my SuperNova chuck are not very long (front to back), far shorter than those on a metalworking chuck, and not serrated.

Next week I shall put on my ice-hockey goalkeeper suit, chuck that mandrel directly in the SuperNova (assuming it will close up enough!) and see what happens........

Originally Posted by Warb

Next week I shall put on my ice-hockey goalkeeper suit, chuck that mandrel directly in the SuperNova (assuming it will close up enough!) and see what happens........

I reckon face masks/visors are an extremely good idea whatever the turning task!!!

Put the supplied mandrel in the Nova chuck, align threaded end with tailstock end and clamp mandrel shaft firmly like you would do with a piece of wood... then, with lathe turned off, grip the threaded end and see if you can pull it out of the chuck. Won't budge... then it is very unlikely to go anywhere, particularly with the tailstock in place at the other end of the blank.

When ready to part off and finish the tailstock end of the handle, do as we have all been doing forever, slow down the speed of the lathe, steady the piece with one hand and complete with the other hand.

Let us know how that goes.

Originally Posted by NeilS

Put the supplied mandrel in the Nova chuck, align threaded end with tailstock end and clamp mandrel shaft firmly like you would do with a piece of wood... then, with lathe turned off, grip the threaded end and see if you can pull it out of the chuck.

With no jaws on the chuck it does work, holding the mandrel tight and square. There's no requirement (or possibility) to line the thread up with the tailstock, because the chuck pulls the mandrel square to the jaws. The process therefore is to simply chuck the mandrel, screw on the blank (with the insert already fitted) and then bring up the tailstock. Because the blank is already square and true, and the insert installed perpendicular to the face of the blank, everything comes together without a problem (as it does when using a Jacobs chuck).

My previous approach has been (using Jacobs) to turn the entire handle excepting the very end, sand and finish with just 1/4" or so of the blank still supported by the tailstock, then part off that last 1/4" and finally sand and finish the end, attempting to keep some inward pressure on the tapers. My new approach will be exactly the same, I suspect, but without the risk of the tapers separating as the end of the handle is finished.....

Now I know that it's OK to chuck metal directly in the SuperNova, the world is the mollusc of my choosing!!