Cole Jaw Mis-Match

[Tom De Winter]

I'm using my Nova Cole Jaws for the first time and the plates all set at an angle to the plane of rotation.
The picture describes it best.

The mismatch is just under 1/8", measuring 0.112". The error is very close to the same between any two adjacent jaws.

Should I be concerned or just mount up the bowl and let it sort itself out?

These jaws are cast and not machined. The chuck is an old one and I'm not sure if the problem is the chuck or the Cole jaws.

 

[hockenbery]

Something is wrong.
The jaws should meet with the surfaces of all the jaws in the same plane.

the cole jaws may be bent or they may need to be installed in a numbered order to have the surfaces in the same plane.
If the jaws are numbered check to see if they are installed on the matching numbered slide jaw.

The cole jaws may not be seated on the chucks jaws - check for dirt, glue, finish

The chucks slide jaws may not have their tops align due to some damage or wear. Remove the cole jaws and put the chuck jaws slides down on a flat surface like the ways of your lathe. Use a light and rotate the chuck all 4 jaws should touch the flat surface.

 

[Russell Nugent]

What chuck are you using them on?
When I got my first set there was a burr I had to clean off the back of a jaw where it seats on a slide.
I don't believe nova cole jaws are numbered.

 

[Bill Boehme]

If the chuck is old then the base jaws may fit a little loose in the slides. Can you wiggle the Cole jaws to see if the problem is just free play of the base jaws? If that is the issue then I don't see it as a problem because they ought to line up when you chuck up a bowl.

I have Oneway Jumbo jaws and Vicmarc Bowl Jaws and neither one has perfect alignment until I mount a bowl and snug up the jaws. Remember that these jaws are meant for low speed. I think that both of mine say 600 RPM MAX. I usually stay below 300 RPM.

 

[Mark Jundanian]

I use my Nova Cole jaws frquently and they should mount flat, not like your picture.

I suspect it is your chuck. Is that a Nova chuck, or one from another maker? Either way you might check with Nova on compatability.

As suggested by others check how well each jaw mates to your chuck slides. The chuck slides should be open a bit when you mount the jaws, and of course, two screws per jaw.

Russel is right, these jaws are not numbered.

Since this is your first use I will mention the original grey cylindrical buttons that come with these jaws perform very poorly. Nova does sell an accessory set of buttons that perform very well. I recommend them.

 

[Forrest Forschmiedt]

When my cole jaws were new I had that happen a few times. I find if I snug one screw without making sure the jaws are fully seated in the chuck it then won't let it seat properly in the alignment grooves on the chuck sliders. With other jaws, snugging the screw generally seats the jaw, not so with the cole jaws. Particularly when they were new, I had to make sure they kind of snapped or popped into alignment before snugging down the screws. Since they are cast, softer metal than the chuck pieces, they will wear in and seat easier after a few uses.

Also, as mentioned, check for burrs and foreign materials on the jaw mating faces.

 

[Tom De Winter]

Thanks for all your suggestions. The chuck is an early Nova tommy bar actuated model.

Once I got over the frustration I had another go at it this morning. Here’s what I found.

I used the screws that attached the original jaws to mount the Cole jaws. They seemed to tighten the jaws ok but they were actually bottoming out in the slides. I shortened them. The heads were also a little to large for the holes in the jaws.

The male dado on the jaws were slightly tapered keeping the jaws from fully seating on the slides. I scraped them to fit.

A couple of the slides had small raised nicks. I lapped the front face of the slides.

There is some slop in the fit of the slides to the body but this really wasn’t causing a problem.

The end result is three jaw plates in pretty good alignment. One is still “twisted” but only half as bad as shown in the photo. Good enough to use for now.