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I need to make a bunch of collets that will protect the lathe's jaws from marking the turning. Also, it should help hold a slightly tapered piece. (i.e., like a pool cue) without damaging the finish.
The outer diameter needs to be 1 1/2" to fit in a chuck as well as a bearing steady rest. The inner diameter will range from 1 1/4" to about 5/8".
The collets will also have a slot in them so they can be tightened in the chuck.
What's a good material? Delrin?
thanks, Jeff :)
I'm definitely no expert, but I've seen some people use PVC pipe as a collet in their jaw chucks.
If its just a one off I've used small scraps of wood. For something more permanent UHMW is pretty decent, I'd be slightly concerned about delrin being to slick but it might be ok - I haven't used it in this context.
I made some out a 1" thick HDPE, it worked pretty good. You can also make HDPE out of recycled code #2 plastic bottles etc., research Google for how to to it.
How soft do you want them? (how hard is the wood you want to grip?). I've seen and made collets from wood - made from a harder wood to grip a tenon and from a softer wood to grip a finished surface, where I've used eastern red cedar and pine: cut a disk, saw the slot to the center, mount in chuck, drill/shape the hole in center for a slip fit before tightening. I think I cut the slot down the end grain to mostly have side grain gripping. I used them in 2" jaws to hold small diameter pieces. Might need bigger jaws for the largest size you mentioned.
If you have Nova chucks have you seen the Nova soft jaws, made from a fairly soft, non-marring material? They fasten to the chuck with screws just like the normal jaws and can be drilled, turned, or otherwise cut to fit the work. They would be too expensive to make a "bunch" but maybe you can find out from Nova what material they use. Or use the same concept to make wooden jaws if you don't need too many. I assume you just need to grip the end of the tapered shafts instead of in the middle.
JKJ
Quote:
Originally Posted by Jeffrey Makiel
Same, generally they've been good for ~low dozens~ of pieces before I get to ham handed and mess up the jaw by over tightening or something.Quote:
Originally Posted by John K Jordan
Nova says they're made out of soft Nylon. Good idea, those wouldn't be to hard to make with a drill template for the mounting holes and then turn as desired.Quote:
Originally Posted by John K Jordan
As mentioned above, I think Delrin is probably too slick.
Wood might be OK, but I'm worried about dimensional stability as I plan to keep the collets for many years.
HDPE sounds like a good suggestion. Is this stuff machine-able? Does it turn and bore without melting?
-Jeff :)
I have used Delrin and it worked well but I did roughen up the inside with the edge of a file to make it less slick (60 grit sandpaper will probably work).
I used different diameters for different jaw sizes; it is so tough that I do not know that you can closed the kerf with the outside 1-1/2 and a small 5/8 interior.
Under 1" I went with a smaller diameter rod.
As an alternative Stuart Ablett used thick kitchen cutting board. Search for "Stuart Ablett DIY Chuck Insert Rings" for a full explanation and pics of the process.
Here is some HDPE polyethylene on Amazon but may be cheaper there or on the bay.
https://www.amazon.com/Polyethylene-...E+Polyethylene
Good input from you all. I'm going with HDPE.
I like the idea of HDPE also. I bought some 8' long sheets 1" thick at a scrap yard and have used it for a lot of things. It saws nicely with any saw and machines very cleanly on my milling machine with end mills, drill bits etc. Great for jig and repair parts so it should make nice collets. I resaw it on the bandsaw to get thinner pieces.Quote:
Originally Posted by Jeffrey Makiel
JKJ
It will melt, if you make your own or even watch some of the videos on how it is made you will get and idea as to how easy it is to melt. As to machining, I used to use it all the time for jigs because it was so easy to shape, drill and I could turn it to shape on my wood lathe. If using it as a holding collet, the melting should not be a problem.Quote:
Originally Posted by Jeffrey Makiel