[jdf001]

Hello, I am attempting to machine a piece of hex stock with a round end, with the round end held in a 5C collet and I'm having issues with the piece rotating in the collet as I machine and was wondering if anyone had a solution to it.

[kstrauss]

Can you reverse the piece and grip it on the hex end in a 5c hex collet?

[SCzEngrgGroup]

You need to really crank down on 5C collets with a sturdy pin wrench for them to grip. It also helps to lubricated the threads.

Regards,
Ray L.

[jdf001]

Can you reverse the piece and grip it on the hex end in a 5c hex collet?

No unfortunately I need to reduce the entirety of the hex portion from 1/2" hex to 3/8" hex.

[kstrauss]

Are you using the right size of collet? The grip range of 5c is only about 1/64-inch.

[CadRhino]

If you have a 3-jaw chuck, you can mount the round part in it and mount the chuck to your table with strap clamps or in a vise.

[Steve Seebold]

What size is the round portion of your part? How long is the round part? What's the material? Hardinge sells collets in .001 steps from 3/16 to 1 inch for the same price as their standard collets (I think).

[MichaelHenry]

Are you using the right size of collet? The grip range of 5c is only about 1/64-inch.

I'd thought that the grip range for 5C collets was more like a few thousandths of an inch. Compressing them more than that can damage the collets.

[jdf001]

I'm attempting to machine a .5" output shaft down to a 3/8" output shaft as shown in the attached picture.

[SCzEngrgGroup]

Typical 5C collets have a range of 1/64", which is about 0.015". My experience has been that is generally all minus - i.e. - a 1" 5C collet will have a useful range of 63/64" to 1". I spent a day several weeks ago sorting a box containing many hundreds of 5C collets of many brands, and they were all sets in 1/164" increments.

Regards,
Ray L.

[SCzEngrgGroup]

I'm attempting to machine a .5" output shaft down to a 3/8" output shaft as shown in the attached picture.

Why not simply use a 3-jaw or 4-jaw chuck? Or are you doing this on a mill?

I've machined several Vex 1/2" hex shafts down to 1/2" round, and 1/4" round, using a 3-jaw in my little lathe.

I assume you realize you can buy those shafts for only $5 each?

Regards,
Ray L.

[mountaindew]

Wow!
Where are the soft jaw people. Most the time you show something like that and its like cut a soft jaw to hold it.
On the other hand cadrhino said what I would use a 3 or 4 jaw chuck and plate to mount it on mill table.
If you have a properly sized 5c and 5c holder mounted to mill table then as ray said tighten it down good.
Hope this helps
md

[yulolaf]

I'd thought that the grip range for 5C collets was more like a few thousandths of an inch. Compressing them more than that can damage the collets.

Yes that's true, there is a reason that they make so many sizes and types of 5C collets as Steve mentioned. http://www.shophardinge.com/productGrid.aspx?catID=6896 there is much more to machining than the typical hobbyist experiences at home.5C is for precision.