Yellow poplar movement

[Bob Glenn]

I am working on a project that will have an eight inch wide poplar board encapsulated by a frame. I have always been able to account for seasonal wood movement through the design process, however, this one has me stumped. With out going into detail of the construction, do you think that eight inches would have enough seasonal movement to open the framing joint? If it makes any difference, the poplar board is from the white part of the log and not the darker yellow.

BTW, I made a table top out of poplar with bread board ends that was 40 inches wide. I noted a total seasonal movement of about an eighth of an inch. Is my thinking correct to assume by that movement, an eight inch wide board will move a fifth of that amount, or something less than a 32nd of an inch? I might be able to live with that. Also, I will be assembling the project in summer, so if anything it should shrink.

Your thoughts appreciated.

[Jim Matthews]

Flat sawn or Quarter sawn?

Do you have forced hot air heating?

How thick is the desired panel?

http://www.woodbin.com/calcs/shrinkulator/

[Bob Glenn]

It's flat sawn. the board is one inch thick. It will be part of the top of a casket. Not worried about what happens afterwards, but the time spent in the funeral home waiting for the big day. So I don't know, but will ask. Thinking now, I may just do away with the framed aspect of the top and keep it simple.

[Robert Engel]

How long will it be there?

Assuming this isn't going to another climate with dramatically different humidity levels, I think if you keep the board in a climate controlled room a while before assembly would minimize movement.

But you're not going to get that much in an acclimated board 8" wide.

That said, plywood is the best option for a framed project. Other than that, a breadboard end or nothing.

[Jim Matthews]

I get .0029x8x10 = .232 inch (at 10 percent variance)

That's just shy of 1/4" movement.

Built now (Summer), that should be the max dimension.

https://www.finewoodworking.com/2013/08/29/calculating-for-wood-movement

[brian zawatsky]

From practical experience I have to say that there is no way on Earth that an 8” wide poplar board is going to move 1/4” in width. Half of that in a very extreme example perhaps. Realistically I would put it closer to 1/16”.

[Bob Glenn]

I've decided to attach the "framed part", actually the molding below the top of the casket, to the casket body and not the top. There will be no movement due to grain orientation in the main case. The top will be postioned by internal rails which will not be attached to the end boards. Thanks for the comments. BTW, I agree, no way the board will move a quarter of an inch.

[Lee Schierer]

Use this chart (http://workshoppages.com/WS/Articles/Wood-Movement-Charts.pdf) to determine the amount of movement you should see in your panel.
413529
The seasonal moisture variation for Indiana is 7-10 %. For your flat sawed poplar you need to determine the current wood moisture level and then use the calculations from the chart to determine how much it might move. If your wood is at 9% the change in winter would be 2% and the increase in summer would be 1%. Therefore if you panel were 12" wide the shrinkage would be .07 x 2 = .14 inches, the expansion would be 1 x .03 = .03 inches. Total seasonal change would be .17" for the 12" panel, for your 8" panel it would be .113" or not quite 1/8".

[lowell holmes]

When I saw the first message in this string, I wondered if it was a political movement, then I remembered, this is
a woodworking string.:rolleyes: