Mystery Lathe tool, any ideas?

Evening all, I picked up a lathe today that came with a few bits and pieces. Most are straight foward apart from this 'thing'!

It has a 2MT fitting, and its quite a substantial bit of kit. A key goes into the side and with the front panel removed the 'teeth' open and can be removed. It looks like something goes into the slots.

If I was a betting man I would guess at some sort of threading tool that uses die heads. Does anyone know what it is or how to use it?

Dave

Looks very similar to one I've got which happens to be a drill chuck - rather an old one.

I also have one which has 2 jaws to hold a square. I was told by someone that it's called a "woods" chuck

Cheers guys

I have one of these chucks,mine has a stamp with three stacked rifles and BSA stamped below .Mine is not now very accurate but I can't bring myself to throw it away.

Frank

These are still available new.

Mine is generally similar but, I think, a little larger. Logo stamped on the side is a small crown so I guess it was made by Crown. Smaller front plate but same style of Veed jaws with angled grooves. Vee angle is 60 degrees so it holds hexagon and round stock. Whitworth form 6 tpi by 1 3/4" diameter thread approaching 2" long in the back for mounting. No register groove so probably doesn't fit a normal style lathe spindle.

Mine has a mostly hollow "tube bolt" with six external slots screwed into the mounting spindle having a square hole buried at the back. Best guess is 3/8" square. There is a short 1/2" spindle screwed into this mounting bolt which could be used to mount the thing in a drill chuck or collet. No way am I optimistic enough to risk that. This thing is a pretty serious lump.

Square at the back suggests that this could have been used as a tap driver but its very long way behind the jaws for a tap with that size of square. Would maybe need 4" or 5" of plain shaft. Vee angle suggests its made for hexagon stock but if thats the case I cant see any advantage over a normal three jaw. Probably less costly to make with simple screws instead of a scroll but still a proper job not corners cut for minimal price.

Clive.

Nooging around Google I found a suggestion that such chucks could be used on drill grinding machines. Sounds plausible as the long jaws should give a decent grip on the drill flutes without being so tight as to damage them. If its bored right through, like mine, and fitted to a hollow spindle there would be no problem in accommodating any drill that would fit. Even with a solid back the drill would need to be quite large before front stick out could become a problem.

Makes me wonder why the preferred form of drill holder for chuck equipped machines, Clarkson, Brierly, Dormer et al was the six jaw scroll type. Effective enough but always expensive.

Clive.

From the Drill Chucks section of an 1895 catalogue

Jason,

Very interesting to see an application where the tang of a drill is being positively driven.

... another myth busted [?]

MichaelG.

Michael

Can't see a split sleeve taper adapters giving much grip on the drill taper when the chuck is tightened. Probably just four line contacts. Likely to be a degree of sleeve distortion when pushing hard on the drill further reducing grip. Big difference between holding power of that and the conventional matching full circle male - female taper pairs. Tang drive is probably just a work-around to get some sort of reliable drive. Very old anyway so not really compatible with modern speeds, feeds and thrusts. No myth-busting involved.

Wonder how the clamping force of direct sideways screw jaw drive compares with that of a modern keyed chuck which works via tapers. Thread on the old device is quite coarse so one might expect considerably less grip than the modern style having both a finer thread and some degree of force multiplication via the tapers on jaws and body.

Clive.

Felder still make similar chucks. About £120 to £160 each. **LINK** . Page juxtaposition suggests they are for use with tooling holders. Clearly a woodworking thing but frankly I don't see a reason for the system. Maybe there is non obvious flange on the tooling holder to butt against the jaws so the tool always goes back to the same projection when re-inserted after changing.

Clive.

From a 1923 J&S catalogue - the drill shown doesn't seem to have a taper shank:

Used with automotive tanged straight shank drills such as this **LINK** . Straight shank for alignment (mostly), tang for most of driving force. Tang is generally larger and more robust than Morse for the bigger drills. Google is your friend for tang specifications, all the ones I've found come as a PDF download link. Also used in Morse tapers with a split sleeve to take up the difference between the morse socket and the straight shank. Rectangular cut out in the split sleeve for the driving tang. Not CNC friendly as its pretty much impossible to replace the drill to the same gauge length every time. Maybe up to ± 50 thou variation.

I thought straight shank tang drive automotive drills went the way of the dodo around the same time as carbon steel but apparently still very common in USA. Allegedly more reliable alignment than Morse taper, which seems a bit dubious. Also said to be more resistant to abuse when Peter and Penelope Piecework really get it on. Which I can believe judging by the state of many of the shanks on my bargain priced taper shank drill collection and the amount I had to ream out the taper on my Pollard 15 AY drill to get a clean surface.

Clive.

PS Happened to look in the Dormer Technical Handbook and found there is a metric version DIN 1809 straight shank drills with tangs.  So clearly still fairly up to date technology.  Dunno if the tangs are same size as the American version.

Edited By Clive Foster on 26/03/2017 16:15:15

Edited By Clive Foster on 26/03/2017 16:15:43

Clive Foster:

Interesting - what, I wonder, is the particular characteristic of the *automotive* industry that led to the tanged straight shanked drill? The object is, clearly, to provide a positive drive but we all need that!

Incidentally, I remember hearing the expression "aircraft drill" and have always associated it with drills with unrelieved flutes.

This way of working ie separating drive and alignment reminds me of tapping chucks which drive on the square end but align on the shank, a much more satisfactory method than attempting to satisfy both requirements with a conventional drill chuck.

PS I forgot to mention that the OP's photo reminds me of the "Little Giant" chuck.

Edited By ega on 26/03/2017 18:24:14

Edited By ega on 26/03/2017 18:30:00