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shapeaholic
03-08-2010, 12:37 PM
I was trying to install my "new" Jacobs Rubberflex chuck, on my whacheon lathe yesterday, and noted that I couldn't get it to run true. I looked that the way it mounts and there seems to be too much clearance between the face of the spindle and the chuck when it is not tightened.

A little more investigation showed that more than one of the chucks I have are the same.

So... here's my questions,
How much clearance should there be between the spindle face amd the chuck back before it is tightened? (I've heard .004" but haven't been able to confirm this)
How much torque should be applied to the cams?
How long is the cross bar on the chuck wrench? (the one I have is obviously not original)

I'm going to double check the spindle for "stuff" stuck on the taper etc. Any other suggestions/

thanks
Pete

Oldbrock
03-08-2010, 12:48 PM
Are you sure everything is clean? When the cams are tightened fully there should be no clearance between the faces. If everything is clean then there is a discrepancy either in the taper of either your spindle or your chucks. I tighten the cams clockwise as tight as I can get them with the supplied chuck wrench, the bar is about a foot long. Machinery handbook will give you the correct taper diameter for the tapers but measuring them is not easy. If you have a factory Jacobs collet chuck then that taper should be right on and if it still has standoff then the spindle nose is suspect and could be ground to specs. Hope this helps, Peter

MuellerNick
03-08-2010, 01:26 PM
The clearance should be 0 to 0.05mm.


Nick

Davo J
03-08-2010, 06:16 PM
I picked up a spare D14 mount chuck for my lathe, and found the taper was slightly smaller so it was rocking on my lathes D14 locating taper depending which cam lock you tightened.
I ended up mounting the new 4 jaw back wards into my original 4 jaw and taking a very small cut off the taper then remove the whole lot, turn it around and try it. The last little bit was taken off with emery cloth. It took a few goes and but it is fine now and runs true.
Davo