Chucks

[LANKFORD]

I just purchased an apprentice chuck from Craft Supplies for my small lathe. I have an older Nova chuck for my large lathe. I notice that the newer chuck has 3 vee shapes for both the expanding and contracting sides of the chuck jaws. Whereas the Nova has a single dovetail. Anyone know of the holding power of the two variations? Also, with the 3 vees which requires about a 1/4" diameter tenon or deep mortice, how about using just one or two of the vees on small bowls for a smaller depth of mortice (or length of tenon)? Is is this getting to risky?

 

[MichaelMouse]

This the one? http://www.woodturnerscatalog.com/cgi-bin/shopper?preadd=action&key=454-0100 Looks like a four-jaw chuck. I see what look like what Oneway calls pin jaws as one option. Has the same advantages and disadvantages as any other serrated chuck. It'll hold, but it's more of an all-in proposition than smooth jaws, because it alters the shape of the mortise or tenon as it bites in. You will want to be careful to get a good push on it to seat the nose against the bottom of your recess or the shoulder of your tenon before tightening, because there will be no slide and seek for best fit like the dovetail.

I own a set of grippers, but found that they didn't suit me. They are safely in the box with the two sets of extra 50mm jaws that came with the chucks I bought used.

 

[LANKFORD]

Reply to MichaelMouse. Yes, thats the chuck.Thanks for your comments.

It does have what is called pin jaws. Has seration on outside but smooth on the inside. The PSI Baracudda chuck has a pin jaw and it is for internal clamping. Has no teeth on outside like the Apprentice. What is a "pin jaw" for anyway? Just for say a dowel or round tenon where you don't need the teeth to clamp?

 

[LANKFORD]

I took a look at the oneway jaws. In Craft Supplies catalog they call it a spigot jaws instead of pin jaw. They say it is a long jaw, smooth for chucking small stuff.

 

[MichaelMouse]

It does have what is called pin jaws. Has seration on outside but smooth on the inside. The PSI Baracudda chuck has a pin jaw and it is for internal clamping. Has no teeth on outside like the Apprentice. What is a "pin jaw" for anyway? Just for say a dowel or round tenon where you don't need the teeth to clamp?

You don't ever need teeth to clamp. If they were required to counter rotation, they'd be 90 degrees to what they are. It appears they are designed to keep the chuck from withdrawing from a recess or a tenon from pulling out. Try to keep your tenon or mortise sized properly for your jaws by varying the width of the wood left around them, and you can take advantge of the larger contact area possible with smooth jaws. Also the bigger dovetail to draw up against the shoulder. If you have machining mess making your jaws less than smooth, save by design, clean it off.

Pin jaws are the all-purpose starters. Mine for the Teknatool series are about an inch long, inch at circular. I bore a 3/4 inch deep 1 inch hole to start small pieces. Only 3/4 so I can bottom the nose of the jaws in the mortise to stabilize the piece. With serrations, you'll want to bring your tailstock up firmly right away, before you tighten. Once the ridges bite, it's tough to adjust depth, which can mean runout.

Use the tailstock for as long as possible, of course. No sense challenging the lathe, the mount, or your skills unnecessarily by cantilevering a badly out-of-balance or heavy piece.

You can also reverse to use the jaws as a wedged dovetail where it suits the effect you want, as in this smaller (~7") piece of OAK. USe the outside grab on dowels, small spigots, or even, by setting the corners in the gaps, square stock you'll be using for finials and such. Great choice in jaws, though I would have preferred smooth outside, like the Teknatool.