Strange WW1 Chuck – 1MT

[Nigel Graham 2Participant @nigelgraham2]

That's a point, Clive – "special purpose machine".

My 'Crown' chuck resembles the Strelinger " Pratt's Improved " but appears to have no provision for a " Positive Driver " tang-key. It is also smaller, under 2 inches diameter, for the same capacity.

I described it as Morse taper but only because when trying it with both taper tooling and plain round bar, MT2 was the best fit, but I admit I've not taken this a stage further, with marking-blue.

[Nigel Graham 2Participant @nigelgraham2]

Old Mart –

The modern advert…

I followed that link too, and yes, first appearance suggests it is for a wood-working machinery stockist.

Then a tantalising glimpse of a metalworking lathe in the pop-up pictures led me to explore the site further. The Italian company sells metal-working equipment too, including a range of lathes from something akin to the small ones from Axminster and Arc Euro, to industrial size and scope.

So I don't think our intriguing chucks are necessarily just for wood-working bits.

[JasonBModerator @jasonb]

My old catalogue says this type are suitable for general machine shop use so definately intended for metalwork

[Clive FosterParticipant @clivefoster55965]

Were straight shank drills ever commonly sold in larger sizes over and, possibly beyond, those now found in reduced shank blacksmiths style?

Handy though blacksmiths drills can be the reduced shank limits the torque that can be applied. Can't run them at book feeds. Especially as much of the time the machine will be too fast. Big ones are awfully easy to spin in the chuck too. Which is bad for both.

If so the Wescott style chuck would have been well suited to holding them. Also good for holding special tooling on large diameter shanks, whether purchased or shop made.

Generally, for good engineering reasons, Jacobs style chucks tend to top out at around 3/4" capacity so would not do for larger shanks. (Larger ones, up to 1 1/2" (?) were made to screw on small lathe spindle noses as a less costly alternative to collet sets for more accurate work but these were always rare and rather specialist devices.)

Maybe not enough reasons to invent the device but plenty to keep using something aready established and on the shelf.

Clive

[JasonBModerator @jasonb]

The same cataloge has drills "blacksmith" type drills with shanks larger than the usual 1/2" and interestingly ones with a larger shank than business end eg a range with 5/8" shanks from 1/8" to 1.5"

Looking at some of the smaller line shaft driven or hand powered drilling machines there are several that just have a socket and side screw so may well have just used a flat on the side of the drill much like a Weldon cutter which would have suited these single shank size drills

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 01/05/2020 10:24:33:

… and interestingly ones with a larger shank than business end

.

The grand-daddy of the modern carbide PCB drill …

MichaelG.

[robjon44Participant @robjon44]

Hi all, I have 2 of these drill chucks, a small zero to half inch one acquired for a few pence at a car boot, this I secured on a ground shaft between centres & turned a nice true running boss on the rear end this enables it to be held in the 3 jaw for a bit of quick & dirty drilling on work fastened on cross slide, the bigger one turned up in a box of "stuff" I picked up at a garage sale, 3" diameter body, 120 degree vee in the jaws, branded to the Skinner Chuck company of the USA, patent 1903, fitted an MT3 to Jacobs taper shank from ARC Eurotrade as I was passing one day, of the type with detachable tang, as the jaws interleave minimum size is zero although I don't have many drills that size, max three quarter inch, will obviously hold hexagon shanks or stock accurately true, I have used it in the drilling machine, milling head & from the lathe chuck, with drawbar when required of course & I can report that the grip can be best described as ferocious, it has never lost grip on a straight drill shank when deployed on a manual lathe or experimentally when nothing else would do on a Colchester Tornado CNC lathe ( needs must when the devil rides) absolutely cannot fault them.

Bob H

[Lee RogersParticipant @leerogers95060]

There was one of these with the Drummond Admiralty B type that I restored. I understand that it was supplied by Drummond with the lathe. Lovely chunky bit of kit but looked out of place on the 1MT.

[Robert DoddsParticipant @robertdodds43397]

Hi ,

I've dug out a similar design of chuck.
It is different in so far as the jaws are recessed behind a front plate that's secured by a couple of screws, Without destroying all it's patina there is no evidence of any makers mark just a 3/4" stamped on the periphery.
As with others it has 120 degree jaws which I had taken to imply that it was intended to grip hexagon bar etc. especially as the back end is screwed and counterbored to fit my Zyto, but that could be a later modification..
The overall quality of the parts appears to be very good and the complexity of the jaw design and their manufacture is impressive especially if it is, as earlier posters suggest, of 18th century build.

[peak4Participant @peak4]

Robert, for your interest, see also another thread, which actually points back to this one at some point.
https://www.model-engineer.co.uk/forums/postings.asp?th=175124&p=1

Bill

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