Using a tailstock chuck in a lathe mandrel

Reading Basic Lathework by Stan Bray page 63, using a tailstock chuck in the lathe mandrel.

I thought that this was bad practice as when force is put on the material from the cutting tool would this be unstable in the tapper.

As most tailstock chucks have a tang then how can the the chuck be held in place as side pressure will knock the chuck out.

Am I wrong on this.

Bob,

Edited By BOB BLACKSHAW on 11/07/2018 02:27:04

Your logic is sound, Bob ... But; given your understanding of the mechanics, there is a useful 'envelope' of light work that you could do quite safely.

MichaelG.

Hi Bob you can get an arbour with a tapped hole in the end and therefore you could make a drawbar to hold it in place especialy if you were using the lathe as a mill with the job fastened to the cross slide.

David

Does it say what he did with the chuck when it was in the lathe? No issues if using it to drill it is only when sideways pressure is applied that you may get issues.

I've done it a few times over the years with no drawbar and no problem. Only turning very small jobs, say couple of mm diameter etc so not a lot of force on the arbor etc. Another way of doing it is to hold the drill chuck in the normal three-jaw lathe chuck, gripped by the larger part of the chuck body.

For holding milling cutters when using the vertical slide in the lathe, I use the regular lathe three-jaw chuck.

I sometimes use an ER16 collett chuck on a morse taper in the headstock, but I use a drawbar with it. The downside is that you can only have a short length of stock inside the chuck.

John

I can envisage using the tailstock chuck in the spindle if I was using a vertical slide mounted on the lathe and wanted to drill an array of holes. The usual chuck may hold the drill but it may not get in close enough if there are features to avoid.

Martin C

There wouldn't be any objection to using a Jacobs chuck when cross drilling bar against a tailstock V would there?

Brian

That would be fine Brian

Drilling is fine. I drilled the 814 holes in the index plates for the Fabricated Versatile Dividing Head using a drill chuck in the lathe mandrel with never a misfire.

Over thinking things. No issues whatsoever with using a good Jacobs style chuck in a lathe mandrel. The work is inevitably small so no force issues. The work will get wrapped up into a pretzel long before you push hard enough to worry the chuck.

Back in the day Jacobs used to make big hollow spindle chucks threaded to screw direct onto lathe spindle nose threads. Sort of poor boys collet substitute system as being significantly more accurate than the ordinary 3 jaw chuck and less costly than full set of collets. Had a 1 1/4" or maybe 1 1/8" capacity one for my SouthBend 9" model A. Excellent device and very useful on the correct work. As I recall it run out was under a thou TIR. And I'd bet most of that was spindle fitting related.

Clive.

You have no issues drilling with the chuck in the tailstock with no drawbar where the headstock chuck rotates the work. So relatively speaking if the chuck is in the headstock and the work is either on the saddle or in the tailstock you can consider the headstock spindle to be stationary and the lathe (Along with the rest of the universe to be rotating around said stationary headstock spindle.

Considering forces the 2 setups are the same so there will be similarly no issues.

regards Martin

Bob,

You are correct.

Fortunately Morse taper drill chuck arbors, threaded to take a drawbar, are readily available in common sizes and threads.

You can also buy a screw in tang for such arbors giving the best of both worlds.

I have bought several from Arc at very reasonable price sand have been very happy with them. (other suppliers may be available).

Eric

Bob,

The fit of the back morse part of the arbor - with or without a tang is less of an issue, as the morse taper is long and a good friction fit can be achieved in the female mating part in the spindle, provided both mating surfaces are clean without dirt or oil.

The issue is more to do with the front end - male Jacobs or B taper which fits into a drill chuck which has a female corresponding fit. The Jacobs or B taper are basically a stub, with a friction fit into the female back of the drill chuck.

The Jacobs/B taper is designed for use in an up/down - in/out movement - so okay for drilling as discussed earlier. Sideways load for light turning, perhaps fine in experienced hands - maybe - but still not recommended as short stubby tapers Jacobs/B were not designed for this purpose. General sideways load - including parting, or holding an end mill in such J/B drill chucks will put on a side force which could dislodge the drill chuck from its mating Jacobs or B taper, leaving the morse part still happily in place in the spindle, with the chuck flying off and creating certain damage.

In the current climate with more new inexperienced people entering the hobby, this is a wrong idea to promote. Some of the new people are unaware that the oil/contamination on arbors/tapers - male and female are to be cleaned off before introducing to each other, to ensure a friction fit. so, if one is to combine the idea of an uncleaned Jacobs/B taper chuck with unclean morse, and then into a headstock, one is asking for trouble.

Similarly, the chances of dislodging the chuck during sideways load are there when working on dirty/or hard materials, especially if such force hits a hard spot in the material it is working on.

If the drill chuck is one which has a threaded female back instead of Jacobs/B, then one could disagree with the above points. Still not recommended in general use on a headstock.

This is my opinion on the matter, based on customer experience over the years.

Ketan at ARC.

Edited By Ketan Swali on 11/07/2018 11:06:52

Just a note:

Removing of oil/contamination off Morse/Jacobs/B tapers / mating surfaces, are a point regarded as common sense to those who have grown up in engineering, and.or those who have been trained to understand the idea and the relating friction fit. However, for those who are new to all this, where they have no teacher, we cannot presume that such people could/would regard this as common sense, and believe me when I tell you that there are a good percentage of new people who are unaware of this.

I have no doubt that some who are reading this thread now fall into this category, and so will be going to their workshops to do the necessary corrections, to avoid future damage.

Ketan at ARC

Edited By Ketan Swali on 11/07/2018 11:19:40

Now that Ketan has got everyone thinking ... Here's an interesting page that I found last night:

**LINK**

http://www.calqlata.com/productpages/00041-help.html

MichaelG.

One other point that makes a "tailstock" chuck less suitable for anything but drilling is that now a lot of users will have keyless chucks which are quite a bit longer than a keyed chuck an any sideway force will be magnified at the taper.

Interesting stuff on that site Michael. Thanks for the link.

Ketan at ARC.

Further to Ketans excellent point about the possibility of dislodging a drill type chuck from its Jacobs or B series taper under turning loads it might be prudent to tap the end of the arbor for a suitably sized screw passed through a hole drilled in the back of the chuck. Should be sufficient to keep everything together unless something totally insane is attempted. The objective is, after all, to use it as a reasonably inexpensive or field expedient collet substitute. Not something to turn a new faceplate on.

Perhaps an ordinary female screw mounting chuck as found on countless hand electric drills secured with high strength loctite onto a suitably threaded arbor might do. Although never associated with high quality the rescued Jacobs "superchucks" I've used for special jobs aren't half bad. Certainly much better than I expected, knowing just how much they had been abused.

Many years ago I encountered a chuck with a screw though the middle into the Jacob taper. Friend bought it round when the arbor wouldn't come out by all normal methods asking that the back be drilled so the arbor could be driven out with a punch or press. The standard unorthodox method (bodge). After drilling the arbor punched out with a fairly normal degree of difficulty revealing that the end had been drilled and tapped for a screw. Cleaning out the chuck revealed the remains of the screw head. No idea of its history but it was sufficiently secure that the screw was unlikely to be a fix for a poorly fitting taper.

Clive.

Even if you fit an arbor to the chuck to take a draw bar, the chuck normally used (Jacobs 35[I think]) is fitted to the arbor with a Jacobs taper, chuck will still fall off.But it's ok to use the chuck for drilling things on the cross slide.

Ian S C