WW (8mm) collet adaptor for Sherline lathe

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ttrikalin

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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.

IMG_6864.jpg


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

IMG_6863.jpg


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.

IMG_6896.jpg


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.

IMG_6902.jpg


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...

IMG_6907.jpg


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.

IMG_6913.jpg


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

IMG_6915.jpg


And sits nicely in the spindle...

IMG_6917.jpg


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

IMG_6916.jpg


take care,
t
 
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
 
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... ::)

 
And this is the modified draw bar...

IMG_7086.jpg


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

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

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

:)
 
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.
15nose.jpg

Tin
 
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...
 
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