How to smooth 5C collet bore?

[lazylathe]

Hi All,

I managed to pick this 5C collet chuck up for a really good price!

It all works very smoothly and is made by a machinist from castings.
There are two issues i have with it is: the bore is not very smooth.

And it has a slight runout.

Is there a way to hone it on the lathe to get it smoother and to lessen the runout?

Apart from those two issues it seems to be very well made!

Andrew

 

[steamer]

You could turn or grind the ID taper....but not the bore.
It should be soft to turning it with a RIGID HSS boring bar with a dead keen edge is possible....Rigid as in the biggest that you can get in there.

It must be right on center height.....

but its doable

Dave

 

[MachineTom]

Yes and maybe. The taper can be hit with a TP grinder, if you don't own one, and have at least a 2hp air compressor an inline air grinder will work. That will smooth things up and make the nose concentric with the spindle axis. But runout from the inside rear area of the collet nose is much tougher to address. First you need to measure a few things. Before you do any rework chuck up something like a .500 dowel the longer the better, Thompson Rail also works, a piece of GP can be used, but a chuck of round something is not that trustworthy, at being round or straight. Starting at a point right next to the end of the collet, measure runout, with a marker highlight the highest point on both the chuck body and the work. Now do the same at a point 1-2" away. Turn the dowel 180° do the same. compare the results are they near the same or way off. Remove the collet and check the runout on the tapered area a couple places, does the LOW point match the HIGH point on the work. Now try the rear bore, the problem there is getting a DTI that will read a relative number that can be used, the issue is an extension on a dti with a .5" arm, add the extension and its 1.5" long, now a movement of .0005 will barely move the indicator, and a movement of .0015 only shows .0005" on the dial.

Take that into account when bringing your numbers together. On my lathe runout near the nose is less then a .001 on my collet chuck, but with some sizes are better and others worse. at 2" everything is around .001-2 I wish it was better as the chuck was bored in the lathe, and the position of everything marked. nose runout is a couple tenths, the rear bore is around 5-6 tenths, but the collets have their own tolerances that add and subtract to the numbers.