I finished this project and it worked perfectly in the shop. Shop temperature 75 to 80 degrees relatively high humidity. When I took it in the air conditioned house, after about one hour the object box which slides over and turns around the main cylinder, bound up so tight the wooden gears would not turn it. Object box and main cylinder are made of walnut rings glued together with grain direction alternating 90 degrees every ring. House temperature 72 degrees with low humidity. This wood movement seems contradictory to me?? The finish is danish oil with sprayed on laquer, 3 light coats.
Replies
Nice Project !
It will be fascinating to see when you put it back in your shop if it frees up and turns again.
Turns again
Yes roc, it did free up when it went back to the shop! amazing. I steelwooled (0000) the main cylinder where it slides inside the object box and sanded the inside of the object box to 400 grit. Back to the AC house and after 20 Hrs. it seems to be free. The cylinders were turned on my metal lathe and and perhaps the slide fit I made was a little too close for woodworking. It is a sloppy fit now and the gears seem to work smoother. Thanks for your reply, it just baffled me that higher humidity would loosen slide fit in wood!
Wood movement due to moisture content changes will cause the diameter of what started out as a round hole to change in diameter. Changing moisture content also will cause the round hole to become somewhat oval. It's just the way it works with the uneven change between the cross grain and the basically no change in along grain.
There was a time . . .
When you would be jumped on by the pack here for suggesting that there was any reason for measuring to a thousandth or making that small of a change in a wood fit up or having measuring tools calibrated fine enough to determine where those slight changes need to be made in wood working.
I bet you were changing your fit up by much less than that, probably just a few ten thousandths.
Blasphemy ! Stone him ! NOOO !
Throw him in the water and see if he floats. If he floats then burn him !
(sorry . . . just getting into the spirit. . . . where was I ?)
It would be great if you could post a photo or a sketch that shows the 90° grain arrangement that you spoke of. I have never done any segmented cylinders etc.
I am thinking that the wood shrunk across the grain and either just made the part smaller and round or it went oval very slightly.
PS: and a photo of the side view. Those cut out details in the uprights are great looking !
not that precise just a little anal
Roc, I'm not all that into thousands of inches for wood but the hand cut gears demanded some precision, I think you will agree. I am not a photographer but here are some more pics for your consumption.The previous post sugest the out of round condition and I agree with this and your response, however I think the alternating grain direction should compensate this condidion ( see previous post).
Gary
I see
I'm getting it. Rings not staves right ? Tricky end grain glue up. Maybe I am still not understanding completely.
(any chance you can rotate that last photo ? I tried to copy and rotate on my end but stays postage stamp size or very blurry when I enlarge it)
RINGS
Maybe this will help. The round disc (2" +) are bored with a hole saw from a 3/4 *12 *6 board . 13 rings I think. Then a 13/4 " hole saw is used to bore out the inner portion of each disc to form the rings. The resulting rings are then stacked alternating the grain 90 degrees for each ring and glued and clamped. At least that is how I did it.Then off to the lathe to true up.
Gary
another trick to
help stabilize is to segment the rings and then stack them. finish the inside with lacquer or shellac. slows down moisture. from sneaking in the back way
a/c in buildings always brings the humidity down to about 38%, which will usually cause problems with wood unless the piece is designed for that condition.
ron
It could be out of round Howie?
for each ring, however gluing everyother ring at 90 degrees should compensate, and the high spots on everyother ring should bear on the high spots of the rings on the mating cylinder. Three rings bear on three rings staggered high spots to high spots theoretically. If that makes any sense?
Gary
This forum post is now archived. Commenting has been disabled