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Fumbler
15th December 2016, 04:08 PM
Team, I am currently using a relatively old lathe with one of the first model Nova chucks but unless I have the tail stock engaged, the piece I am turning moves and goes off centre and gyrates. I am cutting the right tenon for the jaws and butting the piece up to the backing plate but as soon as I put any tool to wood it gets thrown out. I have managed to turn some salt and pepper shakers (first set) and having the tail stock engaged has given the forstner bit a point to centre on.
Any advice on how to stop the piece moving would be greatly appreciated. I do believe I am tightening the chuck enough, but maybe I'm not, or I'm not making a sufficient enough tenon. Videos seen make things look too damn easy yet I don't manage to be able to keep a price straight without the tail stock. Photos to follow.

Fumbler
16th December 2016, 03:11 AM
Pics

pommyphil
16th December 2016, 06:33 AM
Nice looking Shakers :2tsup: If I understand you right you are cutting the tenon to long, the shoulder of the tenon should register on the front of the jaws and not touch the base.

see these https://vimeo.com/woodturning/videos/page:1/sort:date

Rod Gilbert
16th December 2016, 07:09 AM
+1 for pommyphil's answer keep the tenon shorter and only seat on the jaw face.
Regards Rod.

Mobyturns
16th December 2016, 07:57 AM
The above advice is good, however there are a number of things that can cause the problems that you mention. It is very difficult to identify them without photos. I would suggest going to Stuart Batty's "7 Fundamentals" videos on Vimeo and work through the series

https://vimeo.com/68649135

As you are using an older Nova chuck, check that the chuck is "registered" well on the spindle thread. The "register" is the mating surfaces on the chuck body (or insert) that matches and aligns with a complimentary surface on the lathe spindle. The older Midi style chucks with a dedicated thread ( i.e. no insert) had a very small registration surface so are susceptible to problems caused by damage to either the chuck or spindle registration surfaces, debris between those surfaces or from wear of the spindle thread etc. Quite often the spindle thread on the lathe is so long that the chuck is actually aligned on the nose of the spindle thread which can cause problems.

A few photos will help others give more specific advice.

402300

The chuck in the above photo is a Nova Midi with a dedicated thread. The small flat surface at the rear of the thread is the "registration surface". Ideally that should come up tight against a "flat" at the back of the lathe spindle thread.

joe greiner
16th December 2016, 03:05 PM
If the chuck body is too short to reach the spindle registration surface, add a thick washer of metal or stout plastic (e.g. perspex) to fill the gap. The washer also helps to avoid jamming of the chuck against removal. Make sure the washer has constant thickness.

Cheers,
Joe

Fumbler
17th December 2016, 01:38 AM
Thanks for the advice, and the vimeo vids are excellent, and gives a good explanation, I think that's where I am going wrong, I am probably not making as pronounced angle on the tenon. so I will have another crack and see how I go.

Mobyturns
18th December 2016, 06:57 AM
Thanks for the advice, and the vimeo vids are excellent, and gives a good explanation, I think that's where I am going wrong, I am probably not making as pronounced angle on the tenon. so I will have another crack and see how I go.

Some of the Nova jaw sets don't have a pronounced dovetail, more like fairly parallel sides then with a smaller dovetail on the lip of the jaws.

The best way to see what shape tenon best fits your jaws is to remove one jaw from the chuck then place an end of the jaw on a piece of paper (or scrap of wood) and trace the outline / cross section profile onto the paper with a sharp pencil. The outline will be a slight under size of the tenon profile (over size of the jaw profile).

Poorly made tenons, or recesses for that matter, are the source of many problems for novice turners.

powderpost
18th December 2016, 10:32 PM
Have a close look at the inside of the jaws on the chuck. I have one of the very early Teknatool chucks and use it a lot. The jaws on mine do not have a dovetail but a thin "shoulder" that will fit into a 2mm groove cut in the end of the spindle. That may be the cause of your problem.

Jim