Lathe Collet Question ...

[atgordon]

I have just picked up a slightly larger lathe (9 foot long and weighing 1400lb) to replace the previous far eastern import lathe/mill with a very flexible lead-screw (to say the least!). I should add it was so cheap that it probably cost as much in fuel to pick it up.

It is an ex-WD Hendey wartime lathe, with a 4MT headstock spindle. It was shipped with collets but they have long gone, and although it is possible to find the odd 2H collet, they are a bit like hens teeth (plus I'd need to make a collet carrier to attached to the spindle thread ... they are even rarer than said hen's teeth).

Am I off at a complete tangent in thinking it would be simpler to just get a 4MT ER-40 chuck and a use a set of ER-40 collets ...? I would still need to make a draw-bar (which I would have had to do so for the 2H collets anyway.

I realize that I would sacrifice the ability to pass the material through the chuck as you would for the regular lathe collet unless I do some radical machining to replace the 7/16 drawbar with an 13/16 tube threaded to fit the chuck taper. And I have a pretty good 4-jaw that I can dial in for longer stuff.

Also, looking at the collet closing force diagrams, the ER series does come out with some pretty impressive figures ... and I use the same series on my turret mill, and they don't slip at all even when taking heavy roughing cuts.

Any suggestions from old lathe lateral thinkers out there ...

Tony

[wayne]

First Check the socket will accept 4mt full length tooling, my big bore Myford is mt 4 but won’t take full length mt4 tooling I have to reduce the diameter for about 1-1/2 from the small end.

Can you make a back plate? Chester and Gloster tooling both do er40 backplate mount chucks and have the advantage that material will pass through without restriction.

This may be of help too, RDG do MT 3 & 4 test bars at a reasonable price, they also do the proper short headstock mt reducers 4 to 3 and 4 to 2

Disclaimer the above described Chinese tooling, in the most its usable quality but occasionally I have had to return faulty goods, as can happens a with cheap Chinese stuff, its not the suppliers fault.

[atgordon]

Wayne,

I'm OK on the 4MT front ... I have a 4MT dead center and it fully engages.

I have never thought about a backplate chuck ... an excellent suggestion ... really good lateral thinking! I will have to look for a US supplier ... a quick Google search shows a number of UK suppliers but none in the US ... then again, this would be a really good project!

My Chinese lathe was a cheap combination mill/lathe (just Google Central Machinery), and although it had a 7" swing, if you chucked anything larger than 1" and tried to take a reasonably heavy cut even with a live center, the flex in the toolpost/saddle/bed was such that you were cutting a good (rather than a "cleaning of the tool grooves") cut on the return feed, plus I could never "dial in" and hit a dim repeatedly. Happy to pass it on to a guy who was moving up from a Unimat, and he is happy as Larry. My C&G days and production work was on 14-16" swing lathes so I feel much more at home now!

Thanks, Tony