5C Collets and Threading

[Splat]

Got my 5C drawtube completed for my lathe and used it yesterday for some turning. It worked great. I feel the allure of collets for lathe work. I was shooting for 12mm (0.4724") diameter work and ended up at .4731". Today I went to thread via die in the TS holder and the stock was slipping in the new Lyndex collet. I searched but cannot find the work tolerance(?) limits for metric 5C collets. Can a 5C collet withstand the forces from cutting threads? I would imagine using a die puts more force on the work than single-point threading would. Should I just use the 4 jaw?

 

[mmcmdl]

You may be springing the collet if your stock is oversized . A 5C should be strong enough to run a die that size though . The better solution would be a geometric die head .

 

[Splat]

Ok. Found some info that the Lyndex 5C round collets' diameter tolerance is -0.004" to 0". So, apparently going over at all is not good.

 

[benmychree]

Perhaps you did not tighten the collet enough. Using a die does sometimes take a lot of torque, a geometric die takes a lot less and does a lot more accurate and well finished job. Sometimes it pays to rough out a thread single point before using a die to finish the thread. Generally, I single point most threads, but if it is a long and skinny thread, I would likely use a solid (or split) die or the Geometric die head. I also have a Jones&Lampson Hartness die head, they can be found cheaper than a Geometric, as they are less popular and a bit more fussy to set up.

 

[Splat]

I'm going to see tomorrow about tightening it down more. I think I may open up the die a hair for the first run on the second part, then go back with the die tightened back up. I've got only 3 more of these pieces to do so we'll see how it goes. Those Geometric heads are pretty nice if you do a lot of threading. Thanks.