newbie question

Re: newbie question

David Eaves

>Hi there,

I'm pretty new at this game and I'm sure someone more knowlegable will respond. I use the SuperNova chuck though, so have some experince there.

From what you describe I guess you using them in expansion mode. Are you using the 50mm standard jaws?

You don't say what wood you are using, as they all have different strengths. To start with I would leave more, there to play with say an inch, and see how you get on. Also don't take the profile away too sharply, as you then lose the support of the wood above.

Another thing to watch is make sure your dovetail matches the jaws well, if the angle is wrong you will be applying all the pressure at a point which makes it more likely to break.

If you can keep the recess as close to the jaw size as well you will get maximum grip. The only one I snapped out I had gone a bit oversize and as a consequence increased the pressure of the grip at certain points and reduced the support.

Hope this helps

David

Also..

David Eaves

>I meant to say the depth is about right. I think the manual says up to 6mm depth recomended for larger bowls. As 1/4" is 6.35mm that sounds about right. Don't go mad when you tighten the key either. If you do, its more likely to run off true as well as breaking.

David

Re: newbie question

Chuck Ludwigsen

>I agree with David. Also check the following.

1) Is 1/4" deep enough? Cut the recess deep enough to where the entire dovetail jaw face is holding.

2) Is the wood green? If so, try to give a bit more "wall" than half inch.

3) Is your bowl gouge sharp? If your hold is marginal to decent but your tool is dull, you will be working harder to cut and applying more pressure. That force can cause problems and unseat your workpiece too.

Chuck in Memphis, TN.

Re: newbie question

Dinyar Chavda

>Mike:

You can try the approaches suggested, and see if they can work for you.

I usually don't have a "pedestal" on my pieces, particularly the natural-edged ones (e.g., the cherry piece that I posted here), and there is no pedestal on any of my hollow forms. However, I use a tennon to hold the piece, because of similar experiences as yours. The way that I (and most others) accomplish this is to finish the piece leaving the tennon on, and then reverse-chuck it using either a jam chuck or a vacuum-chuck or cole-jaws or a compression-jig, and turn off as much of the pedestal as we like.

You can find examples of this in many bowl-turning videos and books, and you can see how to make a compression chuck in Bill Grumbine's site, http://www.enter.net/~ultradad/.

Dinyar

Re: newbie question

JamieDonaldson

>Mike-I prefer to have my students (and myself!) use the chuck in compression mode with a tenon as Dinyar suggests.Not only is it safer, but beginners are relieved of the need to make bowls with bases as big as the dovetail/jaws-with a jam chuck you have room to make the base much more refined and as small as you wish,a real design problem with neophyte turners.

Thanks for the help!

Mike H.

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