Turning Archive 2005

Subject:
Platter drying experiment 1 (Very LONG, sorry) *PIC*

Gary Evans, Tallassee, TN
>Hi all,

The camphor platter that I turned this past weekend is beginning to warp a bit. I expected it to happen because the blank was quite green when I turned it. But, since this was my first time on the lathe in several months, I wasn't particularly interested in roughing out something to finish later. I wanted to MAKE something! I turned a 1/16" to 1/4" taper, edge to bottom, on the first go-round.

I have been studying the somewhat esoteric science(or is it art?) of wood-drying for a number of years now and thought that I would see if I could deal with the warp as the platter dries.

Here are a couple of pictures of my game plan as the platter continues to dry.

My experiment is to clamp the platter flat and dry it SLOWLY and see what happens. The first picture shows the 2 pieces of 20" x 20" x 3/4" Oak plywood and 4 handiclamps that I am using for my press. The platter had warped more than 1/4 inch from it's original 1 1/2" height, making the space between the plywood sheets somewhat greater than 1 3/4". At present I have it clamped at 1 5/8", measured at each clamp. The blue plastic that I am using for protection of the edge and the bottom is a very open-pored sheeting. I'm not sure what it's intended use was, but it works great for cushioning jam chucks as well as making sanding pads. Anyway, it should allow some small amount of air circulation at the edge and the base of the platter.

The next evolution will be vent holes in the top and bottom sheets of plywood to allow more airflow to the both sides of the platter.

I am blessed to have a creek running right behind my shop (about 5' away.) Since the air in the shop is un-tempered, the Relative Humidity stays pretty high. I should be able to dry the platter very slowly, gradually tightening the clamps till I get it back to the original 1 1/2" height. After several weeks in the shop, I'll gradually introduce it to drier air till I get it dry enough to live in the house. This one is a present for the LOML.

It was interesting to see the behavior of the warp since I turned it this weekend. It stayed pretty flat in my relatively humid shop until Tuesday morning, when I took it with me so that I could show it at our club meeting on Tuesday night.

I am currently working with an engineer friend in his shop, so naturally I took it in to show it off on Tuesday morning. His shop is air-conditioned, as well as having a fan to move the air around. By midday, the platter had picked up the 1/4"+ of warp.

I wrapped it back up in plastic bags once I saw that it was warping. By Tuesday night at the meeting it had relaxed a bit. I doubt if it had more than 1/8" of warp. Tonight I clamped it up and we'll see what happens. I may have to make an unscheduled trip to FL for more camphor if this doesn't work out. 8^]

The original link with a picture of the platter is:
http://www.woodcentral.com/cgi-bin/turning.pl?read=71562

Has anyone else tried this? I would welcome comments and advise. Sorry to be so long-winded, but sometimes a story has to tell itself. You lose too much when you try to edit.

Thanks,
Gary

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