Lid Warp

[dickhob]

I'm in the process of making a side grain lidded bowl (8" x 3") from cocobolo. I rough turned it to about 1/4+" walls yesterday and brought it in to de-stress overnight. The bowl is fine but I have about 1/32" rock on the lid. The high point is predictably near were the pith was.

I didn't plan this out as well as I should have and gave myself a lot less slop for the final turning than I probably should have. The lid has a tenon to fit inside the bowl, with a shoulder that sits (and rocks) on top of the bowl rim.

I'm thinking I can remount and true up the shoulder flat again, but before I try this I'd appreciate some confirmation that this is the right way to go. Or if someone has suggestions, I'm all ears.
Thanks
Dick

 

[robo hippy]

Any time I turn a box, I will rough turn it first and let it adjust for a week or so. Wood always moves, or you can also say that it will 'adjust' to having mass removed. Then return to final shape. It will still move with climate changes. Again, wood moves.....

robo hippy

 

[Bob Salvetti]

Me too !!

Sorry Dick that I have similar problems (and no best answer)
with two Maple canisters.
The lids are fine and flat. The "bowls" have a slight warp after finishing.

I am fearful of trying to rechuck by any method. I have sanded a little on the high spots (pith centers) but have stopped playing for now.

 

[Fred Belknap]

Bowls with lids are problem. They may fit perfectly when you make them but them in a different environment and it may not fit. Small bowls up to about 2" will probably stay pretty flat and round. Some wood moves more than others.

 

[Edward Weber]

As has already been said, wood moves. Some pieces may not be able to be saved, call them a learning experience. If you are convinced that the wood has done all the major movement you can try to re-true it, if feel you have enough material remaining. As far as re-chucking, it depends on the piece but a vacuum chuck should hold just about anything.

A little rocking in the lid gives it character

 

[john lucas]

End grain boxes are hard enough to keep the lid fitting correctly through the seasons. Side grain even worse. When I make side grain boxes of any size over about 2" I make the lid fit loose. I've made boxes from very dry wood that was seasoned for years. Still the lids change their fit through out the year. When You do larger boxes the problem is compounded.

 

[Harry Robinette]

Like everyone said wood moves BUT I started taking the lid and sanding it to fit
the bottom. Then I keep an eye on it for about 3 or4 days and sand just a little
here and there. You should find one place that you sanded every time,I then sand it a little more for just in case. This seams to work pretty good.Of course all the sanding is by hand.
Just my $.02

 

[Bill Boehme]

I have not tried this, but I suppose that you could sand the lid to have three points of contact with the box/bowl. Like a three legged stool, it won't rock, but could still get stuck if either part went elliptical.

 

[john lucas]

Sanding the lid to 3 points will work. I turn my natural edge bowls totally green. Then after they dry I sand the foot flat. That's more or less what your talking about on the top. It should then fit and not rock. If you turn the outer rim of the lid small enough so it won't bind and then flatten the warp it should last for a good while.

 

[Ian Thorn]

I would rough it leaving whatever way you want to hold it for finishing then put it on a rack for a few months and forget it dont be impatiant wood moves or if it is urgent try sanding sealer then you final sand and finish it may help

Ian

 

[MichaelMouse]

The bowl is fine but I have about 1/32" rock on the lid. The high point is predictably near were the pith was.

I didn't plan this out as well as I should have and gave myself a lot less slop for the final turning than I probably should have. The lid has a tenon to fit inside the bowl, with a shoulder that sits (and rocks) on top of the bowl rim.

All kinds of thoughts. I am of the overdry school. I rough to maybe 3/8 and microwave if there are no contraindications. Two things I appear to gain are equalization, because it's done in a perforated vegetable bag, and a bit of case-hardening or fiber set.

Goes back on for finish turning, and gets a wedge in groove type setup for the top. http://www.aawforum.org/photopost/showphoto.php?photo=2246&ppuser=1022&sl=m

http://www.aawforum.org/photopost/showphoto.php?photo=2067&ppuser=1022 http://www.aawforum.org/photopost/showphoto.php?photo=2065&ppuser=1022

This form has proven very stable over wide humidity swings, and it doesn't look too horrible, either. It is a loose fit, but if you're making a lid versus a cap, ought to do. Probably within your reach even now, with thinner stock.

 

[Dave Fritz]

Been wondering how you manage with a threaded top or possibly gluing the top in the case of a cremation urn?

Dave F.

 

[john lucas]

Threaded pieces are definitely a problem. I try to keep the threads small in diameter. My threaded boxes still seem to fit but I go to extremes to make the grain line up when cutting the threads and mating surfaces. Through out the year the lid will shift a little one way or the other and the grain won't line up. It's only off by about 1/8" at most. I'll let you calculate the wood movement based on 16TPI thread and approx. 2" in diameter.
I no Bestwoodtools sells the threader so it will cut up to about 6". I think at that point if you used 16 TPI you might start getting a sloppy fit if the wood didn't move so much that the threads came disengaged. Switching to 10TPI in that case might work.
I made the lid for my Wife's urn a 3" opening. I spread her ashes in a local park so I still have the urn and get to play with the fit every now and then. So far it's fine. The vessel was end grain maple.

 

[Dale Miner]

John

Sorry to hear of your wife's passing.

I think that a threaded vessel pretty much mandates an end grain orientation or perhaps the use of burl or stabilized wood.

Larger diameters should have a more coarse thread pitch so that looseness can be 'built in' to allow for changes in dimensions from weather and other factors and the threads stay engaged.

Some folk use plastic or metal inserts. I think the plastic inserts would move with the wood and need to be on the loose fit side. Brass or other metal may resist movement depending on the wall thickness. If to ridgid though, the vessel may crack instead of moving.

 

[dickhob]

Thanks for all the responses- this is what is so great about this group.

This is a commission for Xmas so I don't have the luxurary of waiting.

I did remount the lid and lightly scrapped the rim. It definitely helped seat the lid.

Combined with the "gives it character" comment, I think I've got a very acceptable result. I'll post a pic when its finished.
Dick