Chuck not centering

[Sir Stinkalot]

After sharpening my tools I have just been enjoying the thrills of rounding down a huge chunk of timber ... The plan it to make a pepper grinder.

I have rounded down the blank between centers and turned a spigot on each end to suit my chuck (Super Nova). That all went to plan but when I mount the spigot in the chuck it doesn't run true. The chuck runs true with no timber so it must have something to do with when I mount the timber in the chuck. I am using softwood and the jaws tend to squash the timber (possibly tightening too hard?). It may also be the case that the end of the spigot isn't square and it is hitting the back of the cuck which is causing it to clamp off center (I may need longer jaws).

Does anybody else have experience with this problem and how is it solved? I really want to get back and play with these super sharp tools.

Thanks

Stinky.

[ubeaut]

I take it you are just using the standard jaws. If so, turn the foot onto the timber. Lock it into the jaws of the chuck (making sure that it is a snug fit) bring the tailstock up into place, then turn it down to round. That way it will be round no matter what.

Unless your head & tailstock aren't in line. Some cheaper lathes have this problem (so do some of the expensive ones but no one will admit it out loud).

What lathe do you have?

If it is an alignment problem then you may need to invest in a 35mm Spigot Jaw set for the chuck, this way you can hold the work without the need to bring the tailstock into play. Not really the best or safest of ways to work but a solution.

Cheers - Neil :)

[Sir Stinkalot]

Thanks Neil,
The late is the Teknatool Nova 3000.
I need to be able to hold the work without bringing up the tailstock as I need to drill trough the endgrain. Thus the work will need to be fully supported in the chuck. I do have the standard jaws that came with the super nova chuck and they do hold the timber but it is possible to move the timber around a little when given a bit of a shove on the far end.

That brings me to another issue. The pepper grinder requires a 25mm and a 38mm hole drilled into the end grain. The 25mm hole needs to be quite deep so I will need to use a drill bit. Is it possible to hold a spade bit in a jacobs chuck in the tailstock and then wind it into the work, if so what speed should the lathe be spinning? I know I should use a forstner bit but that means I have to go out and buy one.

Stinky.

[Sir Chiz]

"It may also be the case that the end of the spigot isn't square and is hitting the back of the cuck which is causing it to clamp off center (I may need longer jaws)."

Sir Stinkalot:
(If I'm reading correctly)The lenght of your tenon shouldn't be so long as to contact the inner face of the chuck.3-4mm should be plenty long enough.
Your "squarness" should come from the "shoulder" of the tenon being flush against the outer-most surface of the jaws,ie, the surface facing the tailstock.
I have found that wood containing both heart and sap wood can compress differently causing off-center.

Spade bits tend to wander and make an ugly hole so start any critical diameter holes with a Forstner bit first.Use a low speed,around 250 rpm.
HTH.

Sir Chizalot.

[Sandy Johnston]

I had that problem with my nova chuck.
It was the adapter for my lather not being 100% square. - I have spent a lot of time and effort to get it 100% and am reasonably happy with the result. Best thought - use a (trued up) backing washer on the lathe's screw where the nova adapter beds into.
However when flipping a turning end for end I now mark the chuck position on the timber and keep it in the same alignment.
This was really evident in bowl work with a thin edge - I could get a 5mm rim when working the screw chuck and when turning it over end up with a 3-5mm rim when in the foot/recess.
Most of this is now behind me and I am just trying to improve my finish.

Regards
Sandy across the ditch.

[ubeaut]

http://www.ubeaut.com.au/ubhome.htm :D