# ER chuck collet



## phubbman (Jun 29, 2022)

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.


----------



## woodchucker (Jun 29, 2022)

nice job. How's the runnout?


----------



## francist (Jun 29, 2022)

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. 

-frank


----------



## phubbman (Jun 29, 2022)

I bored and cut the internal threads first, then machined everything else with it screwed onto the spindle, I’m not getting any measurable runout, which is a first for me.


----------



## phubbman (Jun 29, 2022)

And thanks Frank.  It is a rewarding hobby.


----------



## 7milesup (Jun 29, 2022)

That is really awesome!  You did a really nice job on that.


----------



## Shotgun (Jul 1, 2022)

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?


----------



## phubbman (Jul 1, 2022)

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.


----------



## phubbman (Jul 5, 2022)

Thought I should add a pic of the chuck on the machine


----------



## DavidR8 (Jul 5, 2022)

Great job!


----------



## Road_Clam (Jul 8, 2022)

I bought a cheap china er32 straight shank holder to experiment with. Did not have high expectations of precision. I was no disappointed. Im seeing about .008" tir.  I can correct this by holding in a 4 jaw and indicating but im not sure what collet style i ultimately want to go with . Im also thinking of a 5c setup for more stock diameter capacity.


----------



## BGHansen (Jul 8, 2022)

Check out the comments from davidpbest in the thread below.  He left a post about the advantage of ER collets over 5C.  A number of things favor ER's over 5C.  One off the top of my head is 5C's only grip at the tip of the collet while ER's grip at two axial rings (more stable).  Fewer collets needed for ER's for a full range.  RJSakowski has a nice drawing explaining 5C clamping in the same thread.

I have 5C's at two lathes from 1/16" to 1 1/8" by 1/64".  Most of the collets will never be used, bought the full set just in case (times 2).  Had I to do it all over again, I'd look long and hard at an ER collet chuck.  I have an ER40 collet chuck on my Bridgeport which saves me from reaching up for the drawbar (unless throwing on an R8 arbor tool).  Also have many ER tool holders for my Tormach.

Bruce









						35 vs 72 piece Collet set?
					

Need a complete collet set and looking at these:  https://www.precisionmatthews.com/shop/72-pc-precision-inch-5-c-collet-set-164-to-1-18/   I know twice as many is twice as good - it's also twice the cost and twice the space in my shop. There's not much info on the site - does anyone know the...




					www.hobby-machinist.com


----------



## T Bredehoft (Jul 8, 2022)

...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...

I found that I could (running low RPM on a fair sized (diameter) piece) apply a crank handle on the left end of the spindle and hand crank it back to position easier than reversing the motor. Yes, without dis-engaging the gear train.


----------



## Chris Hamel (Jul 10, 2022)

I have an 11 inch Logan  and am curious whether a transposing gear exists for my lathe.  Did you swap out one of the existing gears?  Can you post a picture showing the gear in place.


----------



## mickri (Jul 10, 2022)

Halligan142 did a video on making an ER collet chuck.  He went through the math to determine what gears were needed to cut the 1.50mm thread on his south bend lathe.  The math should work for your logan lathe.  You would need to use the gears on your logan lathe.  




For a logan lathe these may help.  http://www.lathe.com/tips/met-thd.htm http://www.lathe.com/metric_threading.htm


----------



## woodchucker (Jul 10, 2022)

mickri said:


> Halligan142 did a video on making an ER collet chuck.  He went through the math to determine what gears were needed to cut the 1.50mm thread on his south bend lathe.  The math should work for your logan lathe.  You would need to use the gears on your logan lathe.
> 
> 
> 
> ...


I think that is his best video.


----------



## Chris Hamel (Jul 10, 2022)

Thanks for the info.  I was always curious how to set up to cut metric threads.  Not sure it is worth it since I have a friend with an Enco lathe that will cut metric threads should the need arise.


----------



## phubbman (Aug 16, 2022)

This is the gearing setup I used on my 10” Logan lathe to cut 1.5mm threads.  It worked perfectly.


----------



## Shotgun (Aug 16, 2022)

My Sebastian doesn't have that slot for sliding gears back and forth to set spacing.


----------

