How wide boards for glue-up?

[Niels J. Larsen]

I will be building the bed shown in the picture.

My question is related to the construction of the head- and footboard.

How wide (i.e. high) can the boards/planks be for the glue-up if the gluelines (edge to edge) will be oriented horizontally?

Can I use the maximum width available (about 200mm which equals 8") or must I rip the planks and glue them together (again) to avoid any sagging/bowing of the assembled head- and footboard?

The wood used will be 2" thick shedua jointed/planed down to 40mm (roughly 1.5-1.75") and the maximum height of the headboard is approximately 800mm (32").

[Jamie Buxton]

I'd leave them the full width.

If you're really concerned about bowing because of humidity changes, you can use the pith-up/pith-down layout for the boards. If you were laying the boards out for a table top, you'd set one board with the pith-side face up, the next with the pith-side down, etc. The idea is that if the boards cup because of humidity, the overall panel will stay flat, with some little wiggles. If, instead, you laid out all the boards with the pith face on the same side of the panel, you'd see a bigger bow across the whole panel.

This said, I almost never bother with the pith up/down arrangement. Instead, I lay out for prettiest color and figure. This might bite me on freestanding panels like doors, but doesn't bite me when there's other structure around to keep the panels flat.

The theory behind ripping to narrower planks is kinda weak, IMHO. Ripping them doesn't change the basic physics; the ripped boards will cup given the same conditions. All you get with the narrower boards is that the wiggles in the panel are a little smaller.

[Tony Bilello]

If I am understanding your question correctly, you are asking if there is a maximum length (Height in your case) that you can edge glue boards with horizontal grain orientation. I think.

Well, if thats the case, the answer would be that there is no maximum within reason. Actually the more you glue up with hoizontal grain orientation, the more rigid the final glued up board becomes as it grows vertically.
I personally would stop after a few huindred feet :)

[Mike Parzych]

With 1.50 - 1.75" stock you don't have to worry about any sag at all.

[Chip Lindley]

With the thick stock you are using, no problem gluing wide boards together. Just arrange the grain for a pleasing look! The fewer boards, the easier the building will be. Good Luck!

[Niels J. Larsen]

Thankyou everyone!

You gave me the answers I was hoping for :)

[Joe Jensen]

Boards will change shape with the humidity changes throoughout the year. Flat sawn boards will move a lot more than quartersawn. If the grain when looking at the end of the board is perfectly perpendicular to the face, the board will not move at all. If it's almost perpendicular, you will get little movement. With flat sawn (when looking at the end, the grain mostly goes parallel to the face and you an see curvature to the grain) that board will move a lot. There is a great book "Understanding Wood" that goes into good detail. They also have tables showing radial and tantential shrinkage/expansion with moisture changes. With these tables, and knowing the summer/winter relative humifity in the home, you can calculate how much the wood will warp. Ideally one your flattend the boards and glue up when humidity is exactly in the middle of summer/winter. That way it would move one way summer and the other winter.

Seriously folks, this book is a really important book to understand if you want to build furniture to last generations.

[Peter Quinn]

Edge glue them at that thickness in the widest format available (8" for instance), orient for the best grain match for your species, and don't worry. They may move a bit over the seasons and years, but so what? As long as the joinery remains strong and tight, the head and foot boards abut nothing, and you have little visual reference through which to judge this movement. It is movement that will not cause problems in a free standing piece of furniture, and unlike a table top in a glancing light, it will be difficult to actually see any 'wiggles' that present themselves. Good luck and enjoy your work.

[Niels J. Larsen]

Will your answers change if I go down in thickness to e.g. 20mm (approx. 3/4") ?

[Jim Becker]

I use wide boards almost exclusively, regardless of thickness...