Thursday, June 28, 2012

Bowl Distortion, continued

Hi Everyone,

A couple of days ago I wrote about the silk oak bowl and how it had distorted after drying for a couple of months. The bowl was so twisted that it wouldn't sit flat on a table and I couldn't attach it to the lathe.  The inside was a mess too so the only way to save the bowl was to do a substantial re-turning of the bowl, both inside and out and the bottom too.

To turn the outside and bottom of the bowl required re-mounting on the lathe with a set of Cole jaws:

 Cole jaws consist of 4 pie-shaped pieces of aluminum that has been drilled to accept rubber plugs which are screwed onto the surface of these plates. The whole thing is screwed onto the top of the 4 jaw chuck:

The bowl is then placed on top of this assembly and the jaws of the chuck are tightened. This holds the bowl in place and allows it to be attached to the lathe:

Cole jaws are great for correcting a twisted bowl's outside surface. It's not made for heavy duty turning and I don't use it above 200 rpm. This allows me to gently shave the surface and re-turn it to a round shape with a flat bottom.

Here is a photo of the bowl in the middle of turning. I've cut a small groove in the edge of the foot and if you look carefully you can see that the groove is round while the foot is oval shaped (and not level):

Here is the bowl with the sides and bottom re-turned, flattened and rounded off. I'm not going to turn the inside for the moment. I'm going to see how the outside works out and if it stays round and flat. If not I may have to re-turn it again and if I do, I'll need every bit of wood to do that. Stay tuned for more about this one.

Here is another bowl in the Cole jaws. This was a small bowl I turned earlier this year and it twisted a little bit too. I've placed it on the lathe and the bottom photo shows the bottom and sides re-turned and flattened:

My last project is a jewelry box out of myrtle wood. It's going to be a Christmas present for my mother in law and as it's unseasoned wood, it's drying out in a dry bag for the time being. I'll post photos later on along with a discussion about how that will be made.

Ok, the shop will be closed during July for cleaning and repair work and just to show you all that I'm not just sitting around, I'll post photos of the repair I'm going to do on my garage floor.

Thanks for hanging 'round the wood shop and I'll see you soon. As always feel free to email with questions or comments about wood turning.

See you in August,


1 comment:

  1. When I make bowl rough-outs I leave a small spigot inside. Then when it is dry I can hold that in the chuck jaws to true up the outside. The spigot distorts but still holds. If it's too badly distorted, I alternate between the inner and outer fixings until they are true. I think this gives a more solid hold than you get from Cole jaws. My bowl pages