Wide Panels and Wood Movement

[Mark Kristan]

I think this may be my problem but I'm gonna try to get feedback from others about it. I built a simple box to hold an A/V receiver and speaker, I used box joinery to attach the bottom panel to the bottom of the sides and a lock mitre to attach the top panel - they are all 10.5" wide (poplar). It is not fitting together all that well, might still work but I am worried that glue may not keep the joints together over the long run. The guy at the lumber yard suggested I should probably edge joint narrower panels together, I have tried edge joining a couple times and just stink at it so I avoid going that route but if I have to watch a few more vids and probably make better jigs (like cauls) so be it, but do others agree that wood movement in single panels that wide (10.5") will probably cause this?

[John TenEyck]

What do you mean by "not fitting together all that well"? Are the panels cupped? If so, maybe you didn't let the wood acclimate to your shop before you jointed and planed it? Or are you using S4S from the lumber yard or store? If your wood is in equilibrium with your shop, you should not have large problems with it cupping after you face joint and plane it unless the RH is changing a lot and/or you laid it face down on your bench. What was the background behind the wood you used?

A glued up panel is more stable than one wide board, in terms of cupping, but the total expansion/contraction will be essentially the same. If you are having trouble edge jointing boards to glue up panels then it's time to teach yourself that skill. Get some scrap and practice until your edge jointed panel will stand up vertically on your bench.

https://lh3.googleusercontent.com/2isjaO2WjZcF6LZ4mH_kqyZRNLa_RFyBimfgZMwOdR3SfVWvFx p0lwMHKbUF6a6OO0iRq9j1WDn2uNnmRhn9WfaB4u8_kapTH4yN OT51gCk2_xd1Lh-lhxbncFFttawpE2hqlFZvVwfMt3CYxAtctaXeHstWpfVSZ5wzZ GDkHudmG21NoTixGszKoX9pRIFCvjfVQ1TCK-CTDAgRmNGemTNRsbbcv7suzUYcNb5cLkEwLmsBg1wQOMQvQR0Q Tex841jN6DcZPqM4SetR2lVB6V8X9bZkGfwOID4Ut5US3dx5ux BBpDb2shcPoNPjeHIh1wVWVlpXaSE4qL1kFgO1jBkJkN2h6A93 uqDmdJVf_YG9a-OXsSAwlU9el8TBVzH2R6xoZMg_eKgCso_HzMsBuTfHrhMQWBL9 lDJA263gKQk-xq89u1UvnGMRp8OBZcg1AWTDVHPzZB8afBGl4tNUsuywCzVMrQ i2bshtKx24xRwOXXww1Uryxxw0sinFhVVOD5DqPUv9rVkXEYc7 GbF9sMyophvkR_MQca9rhP_FL6AENPDVEUYcNDZq2zZQIvYJsn _gNXUlA60zm4tDeP_b42MFGmFARxIMFWCEFbA6SEbh8d76h0dL =w838-h628-no

John

[Brian Tymchak]

Mark, I'm not sure what problem you are having. A few pictures would help us better understand.

If you've built a 4-sided box out of hardwood and then glued in a bottom, you will likely have some issues at some point. The bottom will expand with seasonal moisture and push against your corner joints.

[Jim Becker]

If the panels that make up the box are made from the same material and the grain direction is consistent, then wood movement shouldn't cause much of an issue regardless of the joinery chosen because everything will move in the same direction. If the lumber yard dude was trying to talk you into using narrower lumber to build your panels, that's just an "opinion". Wide lumber and narrow lumber can be similarly stable if dried and milled correctly.

[Brad Barnhart]

the guys are right! i do a lot of glue ups for scroll projects, & i use rough cut lumber at that. the two important things for a glue up is a good flat face on both faces, & jointed square on both edges. from there, when you start to glue your pieces together, run your grain one way. The important thing is to make sure your faces & edges are flat & square, CLEAN! I'm in agreement with the others, a couple pictures to show us what your meaning of "not fittin' together well". another thing i'd say, use a glue brush to put your glue on the edges to be glued. then rub them together a little to make sure you get glue on everything. It don't take a lot of glue. just curious, are ya hand jointing, or runnin' your lumber over a power jointer?

[jack duren]

What do you mean by "not fitting together all that well"? Are the panels cupped? If so, maybe you didn't let the wood acclimate to your shop before you jointed and planed it? Or are you using S4S from the lumber yard or store? If your wood is in equilibrium with your shop, you should not have large problems with it cupping after you face joint and plane it unless the RH is changing a lot and/or you laid it face down on your bench. What was the background behind the wood you used?

A glued up panel is more stable than one wide board, in terms of cupping, but the total expansion/contraction will be essentially the same. If you are having trouble edge jointing boards to glue up panels then it's time to teach yourself that skill. Get some scrap and practice until your edge jointed panel will stand up vertically on your bench.

https://lh3.googleusercontent.com/2isjaO2WjZcF6LZ4mH_kqyZRNLa_RFyBimfgZMwOdR3SfVWvFx p0lwMHKbUF6a6OO0iRq9j1WDn2uNnmRhn9WfaB4u8_kapTH4yN OT51gCk2_xd1Lh-lhxbncFFttawpE2hqlFZvVwfMt3CYxAtctaXeHstWpfVSZ5wzZ GDkHudmG21NoTixGszKoX9pRIFCvjfVQ1TCK-CTDAgRmNGemTNRsbbcv7suzUYcNb5cLkEwLmsBg1wQOMQvQR0Q Tex841jN6DcZPqM4SetR2lVB6V8X9bZkGfwOID4Ut5US3dx5ux BBpDb2shcPoNPjeHIh1wVWVlpXaSE4qL1kFgO1jBkJkN2h6A93 uqDmdJVf_YG9a-OXsSAwlU9el8TBVzH2R6xoZMg_eKgCso_HzMsBuTfHrhMQWBL9 lDJA263gKQk-xq89u1UvnGMRp8OBZcg1AWTDVHPzZB8afBGl4tNUsuywCzVMrQ i2bshtKx24xRwOXXww1Uryxxw0sinFhVVOD5DqPUv9rVkXEYc7 GbF9sMyophvkR_MQca9rhP_FL6AENPDVEUYcNDZq2zZQIvYJsn _gNXUlA60zm4tDeP_b42MFGmFARxIMFWCEFbA6SEbh8d76h0dL =w838-h628-no

John

Boards with still warp. It's nature..

[John TenEyck]

Boards with still warp. It's nature..

I was addressing the OP's comment about having trouble jointing edges straight for gluing up panels.

John

[jack duren]

I was addressing the warping....

[Mark Kristan]

Alright, thanks for the replies all, I guess I have a few issues to address (too late for pics now, it is put together and I'm using mechanical braces at the corners - will see how it holds up, lol). What I mostly wanted to know is whether people agreed that edge joining smaller boards is a lot more stable than using wider boards and most people seem to think otherwise, so I will continue to avoid that step when I can. This is rough sawn poplar, I milled it on a Hammer jointer/planer. I had problems with a few joints, in most cases the problem was with what I did with the router (like tear out at the end of a lock mitre or a sliding DT that I had to redo the tail), but it is not perfectly square and the biggest joinery problem I had was with the box joints connecting the bottom panel to the bottom of the two sides. It was very difficult to get the pins and tails to line up correctly, I'd push the boards together on one end (side bottom), they'd pop out on the other, kinda thing (I had less trouble with this joint on other, smaller boxes, perhaps 5" wide panels). There were a couple of boards (one became scrap) that, after I milled them, then let them sit in my shop for a bit, they'd just cup, pretty sure they were good n flat at one point but I milled them again and the same thing, they just would not stay flat - maybe I should have started over with a different piece of wood, that one was just gonna keep cupping no matter what I did? Maybe I used a piece that had not been in the shop for long enough, the wood that I used a humidity meter on was around 6 or 7 percent moisture content. I didn't really think about grain orientation, I mean I started with a board that was maybe 12" wide and milled it down to 10.5" so I don't have any cross-grain joinery going on. I don't get nearly as much time as I'd like to spend in the shop, I have a lot to learn about the craft, thanks again for the replies.

[Jerry Miner]

Not too late for pic.s

What I'm not understanding-- and pics would help-- is how the grain orientation is arranged in your box. It is unusual to use box joints for the bottom of a box, and I wonder if you are cutting box joints into the long grain edges of your pieces.

10.5" wide panels will move-- but how that movement affects your box depends on how you orient the grain and joinery in your box.

If you are having less success with the fit of the box joints in a 10" panel than you have had with smaller panels, it is probably due to the "cumulative error" associated with most box-joint jigs--- the wider the board, the greater the error in the joint.

[Jim Dwight]

If the panel width is the same, it will move the same amount if it is one wide board or several smaller boards. It is possible that several smaller boards will warp differently but not assured. You can guess based upon grain orientation but it is a guess. The project has to be designed such that the joints pull the cupping or warping out when you fasten the sides together. That works well as long as it is small. If it's badly warped, then I would cut it in two, flip one piece end for end, and glue it up again. Or, better, use it for another part where I can cut it into narrower pieces.