Shop made wooden jaws for a 4-jaw chuck.

[Joshua Dinerstein]

I have been thinking my way thru the details on a few projects. After numerous trips to the local library I have found a great deal of information and the idea of wooden jaws has come up a couple of times.

In an older book from the late 70s there was a picture and a 2 line explanation for that picture. The picture was of a set of "step jaws" made out of wood. mounted onto the chuck in some undisclosed way. The 2 lines basically said that the author had found these extremely useful for gripping things for turning at different diameters. And that the set as shown had been in use by the author for about 10 years. They had that slightly worn patina that wood gets thru years of use and abuse and so it was quite possible.

From a more recent era we have David Reed Smith's website which talks about wooden jaws. He shows a jig that is used for making small pieces but is re pleat with warnings not to go to big. His specific comment is:

Please keep in mind that the mounting power of wooden jaws is less than that of metal jaws. A serious catch can break a jaw away from the mounting screws.We also have Bob Hamilton's website and videos often showing his large and deep wooden jaws. Bob has posted that his are mounted onto metal flat jaws from OneWay mfg. In a recent posting Bob talked about the weakness of screws and the worry of them shearing off.

Also Darrell Feltmate, on his site aroundthewoods.com, shows how he made his out of plywood with no metal backer jaws. His has no warnings per se and just pictures and details of construction.


Now my hopes for creating some wood jaws focus around a number of ideas, I want to turn some small objects, rings bracelets etc..., as well as potentially create some of these bowl bottom jaws.

This has left me wondering if it is safe enough, what kinds of woods to use for the jaws, and wether or not I should get some metal backer jaws or just screw right into the slides on the chuck a la Darrell Feltmate and the unknown author.

Anyone have any experience or words of wisdom that they would like to share?

BTW, I know that almost all of these things are available in a machined metal format. "Raffan Step Jaws" for my Vicmarc chuck, Cole Jaws galore for basically every chuck, etc... What intrigues me about the process of turned jaws is the chance to alter the size of the gripping surface when needed and to grip "finished" pieces of various sizes and shapes without marring the finished surfaces. And cole jaws/bowl bottom jaws of much larger sizes than the 10" max cole jaws I currently own.

Thanks!
Joshua

[Ryan Baker]

A few thoughts:

- Creating your wood jaws with the tenon on the back (to fit the groove in the slides) will help relieve some of the stresses on the screws (and less "flex" in the jaws that might tend to crack them). Mounting them on Cole jaws would be even better in this respect, and would make the jaws much simpler to make.

- Watch out with large size jaws. All of the problems and dangers will increase with the size of the jaws. Just as with Cole jaws, you need to keep the speed down when using the wood jaws. They will not be well balanced, and likely will introduce some vibration as the jaws get bigger. They will have a lot more mass to spin than the metal jaws. The forces on the wood jaws increase a lot as the jaws get bigger (and spin faster).

- The idea of wooden jaws bigger than 10" scares the beejeebers out of me. I wouldn't go there if I were you unless you are turning VERY slowly. (Like many turners, I almost never touch my Cole jaws any more since there are other much better ways to do the same thing. I wouldn't want bigger Cole jaws.)

- Seems like a lot of work to me. It would take more than a few minutes to make a decent set of wooden jaws. For one-off jobs, that is a lot of effort. (For frequent jobs, you should just get the real jaws.) You can get a set of the Nova soft jaws for around $25 and turn them to whatever size/shape you want. Maybe you have the time, but to me, the time I would have to invest in making the jaws is worth more than the $25. If you had some decent jigs set up so that you could machine out a set of jaws very quickly, that might make it worth doing. But you would have to need a lot of custom jaws to be worth that.

- Something like maple should work quite nicely.

- Since you already have Cole jaws, the easiest path by far would be to make add-on wood jaws that bolt onto the Cole jaws -- which they are actually designed to do. That would be a lot easier and safer than making all-wood jaws.

- Make sure they are beefy enough and think about the grain direction. The workpiece will put a shearing force on the jaws and want to split along the grain.

[James Combs]

How about using a good grade of 3/4 ply wouldn't that reduce the splitting tendency? If you needed thicker then 3/4 glue up another layer of 1/4-3/4 onto it till proper thickness. Once it is mounted onto the cole jaws turn "IT" until it is symmetrical and balanced. Wouldn't that work?


A few thoughts:

- Make sure they are beefy enough and think about the grain direction. The workpiece will put a shearing force on the jaws and want to split along the grain.

[Leo Van Der Loo]

How about using a good grade of 3/4 ply wouldn't that reduce the splitting tendency? If you needed thicker then 3/4 glue up another layer of 1/4-3/4 onto it till proper thickness. Once it is mounted onto the cole jaws turn "IT" until it is symmetrical and balanced. Wouldn't that work?

You don't want to use plywood James, it will delaminate quite easily, yes learned that the usual way, not a good idea :(

[Richard Madison]

Joshua, For small objects the wood jaws that are screwed directly to the chuck slides should work well. I would use oak simply because I have some, but many hardwoods should serve. Think I posted some small jaws made from steel angle a while back.

[Tom Giacomo]

I guess I'm going to pull against the grain but I have built several large cole type jaws out of birch plywood. The first was to hold up to 15 inch objects on my old 15 inch swing lathe, then I got a PM3520 and made up a 24 inch set of coles. I used a PSI type chuck and purchase longer screws. I have used it for several years now and have had no trouble, I use it mainly as a finishing holder not doing any real heavy cutting with it. As you may notice I used rubber chair leg bottoms as grippers. It will hold from 8inch to 22 inch objects.