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Need help south bend 9 er40 collet Chuck build


Dec 22, 2023
Hello, anyone interested in making a screw on to the spindle er40 collet chuck adapter for a south bend 9? I will supply the bearing nut.
( picture for reference ) compensated for time & materials. Regards Tony.
Please email: [email protected]


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To be specific about what your looking for, it would be called an ER 40 collet chuck threaded to fit your spindle nose and not an adapter. Given the precision involved just getting the threads and counter bore sized correctly for your own particular lathe so it provides decent repeatability each time it's mounted wouldn't be all that easy, even less so if you can't accurately measure what you have for your own spindle nose.

Ignoring that, just building the chuck would take a fair amount of time at least on manual equipment. I'm not interested, but if I was I'd be wanting well north of a couple hundred $ and I still wouldn't make any guarantees it would fit and repeat well enough. There's lot's of YT videos around showing how to build your own for a rough idea of how much time it might take. And ideally that chuck really ought to be built from a good tool steel, hardened and then finish ground. Unhardened steel can work, the durability of it's working surfaces would be a whole lot less of course. If it were me I'd machine your own out of maybe 4140.

Ok it sounds like you might not have a lot of experience, but even the failures will teach you what doesn't work. So I think I'd practice machining the first few from either mild steel or even aluminum until I knew I could get an acceptable result on the more expensive material. There really isn't any short cuts to gaining that experience.

And without known low run out collets, the best and most accurate collet chuck you can produce might be wasted if some of your collets still have .002"-.003" or more run out. I have a couple of 3 jaw and even a few drill chucks that are far better than that. So if the collets can't easily beat what I already have, there's zero reason to use them. When I bought my 40's I paid multiple times more than the off shore collet sets cost just for a reputable brand name and get guaranteed well under .0005" run out numbers.