WW (8mm) collet adaptor for Sherline lathe

[ttrikalin]

WW collets are 0.312-.313 in width and they are supposed to hold really small work very accurately. I got my self a few numbers from fee-bay and set out to make an adaptor for my Sherline lathe. This is a simple sleeve that fits into the Morse 1 taper of the spindle and holds the collet. Sherline sells the adaptor (and it's not too expensive), but I wanted to play a bit .

Note that the 8mm version of such collets is a bit different in diameter (0.314-0.315) so one would need a different adaptor (same as this one with larger bore).

I posted the plan with the dimensions on this website:
http://web.me.com/ttrikalin/Machining/Machining_home.html

To ensure concentricity, the piece is machined in one setup. First, I indicated the MT1 of the spindle and set the compound cross slide to the correct angle.

I found good use for an el cheapo dentist’s mirror from Walgreen’s.

I chucked a 1.6” long piece of 0.75” diameter 6061 ally. After facing, I turned down to 0.700 a length of ~1”. Then I turned down to 0.478” between 0.150” and 1” from the end. I had to use a combination of passes with left and right hand tools mounted on the compound cross slide. At this point the (already indicated in) compound cross slide is a back-cutting tool holder; I moved the whole cross slide the normal way.
Afterwards I turned the Morse taper with the compound cross slide. I used a left hand tool and I was cutting until 0.030” from the distal shoulder -- see plans.

I drilled to 0.25” and then bored to 0.313”, testing with a collet for fit. The final bore is a 20 degree taper to accept the head of the collet, as shown below.

I only have a single boring bar that practically bores from 0.300” and wider... So to bore I am using 3/8” endmills held in my dial indicator mount. With the endmills I cannot bore deeper than approximately 0.6-0.7”... and thus the bottom part of the adaptor below is still the drilled 0.25”... You can barely see in the photo...

So i made a mandrel, and mounted the part on the lathe to clean up the bottom 0.1” or so... Here you can see the way I bored the back... I really have to make small boring bars... Oh well...
Concentricity is not a must in this final cleanup... it just frees the bore up.

The WW collet fits very nicely with no play...

And sits nicely in the spindle...

The only thing left is to modify (elongate) this $5 drawbar from fee-bay to fit the lathe...

take care,
t

 

[Deanofid]

That's a neat project, Tom. Nice old brass bed Sherline you have there, too.
Still the original AC motor, or have you put a DC on it?

Dean

 

[ttrikalin]

Still the original motor... and still the original 3-jaw chuck... I got it used and a bit abused :'( ... but i restored it to the factory specified accuracy... :

 

[ttrikalin]

And this is the modified draw bar...

I cut off the el cheapo draw bar from feebay, turned down a screw cut to length and pressed it in...
There's a piece of shrink tube (the black sleeve of the steel bolt) that I put to hold the washer (that positions the bar on the sherline spindle)...

The blue part is a clip made of delrin... Because I have an assembly of WW collets, some longer and some shorter I use this spacer to alternate...

Oh well, yet another hacky tool in the toolbox...
take care,

tom

 

[Tin Falcon]

Nice work. Are you planning a thread protector as well ?
I may need to consider a similar adapter for my old machinex.
Tin

 

[ttrikalin]

what is a thread protector? :hDe:

If I knew what it were I might make one...

 

[Tin Falcon]

A collar that screws over the spindle threads. It protects the spindle threads from a possible oops and keeps the chips off when a collet is in use. typically installed before you put your collect adapter in place. you will want to add a couple holes for a pin spanner and or knurl for grip.
Apparently can be used to remove the collet adapter as well.
Actually called a spindle thread protector.
here is a photo of one for a 1-1/2 8 spindle nose available from tools4cheap.

Tin

 

[ttrikalin]

thank you.

I cannot cut threads now, nor do I have a proper tap.
One of the (distal) future plans is to set up a (the) lathe for CNC threading...