ER chuck collet

P

phubbman

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It took me a while to get it done, but I made myself an ER32 spindle chuck for my Logan 10” lathe. I bought the nut and a set of collets, then machined myself the thread on chuck body. I started with a 2-1/2” slug of what I think was leaded steel, then spent many hours turning most of it into small curls and chips. I’m learning the basics here, and this was my first effort at internal threading (1-1/2” x 8tpi spindle thread), metric threading (40 mm x 1.5 pitch for the nut), or turning a taper (8 degree internal to compress the collets). My hack pseudo machining skills only reared their ugly head once when cutting the metric threads (they are a touch loose, but very serviceable), but everything else worked out perfectly. I’m certainly happy with the results and will put it to good use right away. C384AAE2-4FE2-41C0-B51F-6731532C2668.jpegCEA0FE48-D854-4CD1-836F-F58D6FF1A279.jpeg6460D916-51BD-41EE-8C8A-38B5D39F91F0.jpeg92D9B70C-3EE9-4B6A-9CD1-3528E313C117.jpeg747E0239-25C5-428D-9894-A6A727B40980.jpeg
 
It’s a great feeling to knock off some of those “first time” operations and an excellent confidence builder. Good on you for seeing it through, that’s a decently ambitious project and the end result looks great. :encourage:

-frank
 
I love it. I'm planning out doing the same thing for the Sebastian I just bought. It has a non-standard spindle thread (2 1/8" x 8), so I can't even consider buying one.

My issue is that I don't have metric threading capabilities, and this thing seems to have a rather complicated gear train, with none of the gears stamped with the teeth count. I want to find out how close I can get to 1.5mm (.0591") threads without changing anything. How did you cut the metric thread? How close to exactly 1.5mm is close enough?
 
I bought a 37/47 tooth metric transposing gear. It is a 3d printed compound gear made of nylon. It works perfectly. There isn’t much stress on the gears when cutting threads, so the plastic gear is more than strong enough. To get an exact metric measurement you would need a 127 tooth gear and a 100 tooth gear, but the 37/47 tooth gear gets to within .02% or something like that, which translates to a couple of thousandths over the length of a foot, if I have it right. Since the thread length on my er chuck is less than 3/4”, the discrepancy is negligible. It all works just fine.
To get a 1.5mm pitch gear train figured out for your Sebastian, you might try asking here or try googling it. I do recommend practicing on a piece of scrap before going at it on your work piece. Since you don’t release the half nuts when cutting metric threads when using the transposing gears, you need to back the cutter off and reverse the motor to back the carriage up for the next cut. It’s no problem, but just a little different than the routine you might be used to.
When shopping for transposing gears you will need to match your existing gear’s pitch, pressure angle, and thickness. If the bore is off, you should be able to modify it to work.
 
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