Laminating parts

[rblusthaus]

Hi all

When laminating multiple pieces of wood together to make a larger piece, how many laminations are optimal? I mean, should i try to stick with an even number of laminations? Should I try to reverse the growth rings to kill the tendency to cup? Am I over thinking this?

I need a few 4 x 4 (or thereabouts) that are 48inches long, made of some yet to be chosen hard wood (oak or maple). I intend to laminate 5/4 boards that are wider than the desired width, then plane to finished dimensions.

Should i use thicker stock then 5/4 to start with? or thinner? Do I want 3 total laminations or 4, or more? I kinda assumed that I would want an even number, with growth rings reversed, but then thought a question or two here would be in order.

The pieces I am preparing shall become the support pieces of a treadle lathe, and as such, they must remain straight and true. Any suggestions? Thanks in advance.

[Stretch]

Well, normally I don't worry about it at all, but since you're making a machine out of them I'd be a little more careful. I'd say shoot for even laminations alternating the growth rings. Better still would be to make them out of quarter sawn lumber. If you don't have any or don't want to pay for it, often times the edges of wide plain sawn boards are at least rift sawn. All that being said, I usually do laminations without worrying about anything but if the grain on the outside looks the best and I've never had one warp.

[TDHofstetter]

The absolute IDEAL would be about eleventy-seven layers of mahogany veneer, with alternating growth rings... but that's harvesting the last straw from the field. For what you're shooting for, three or four laminations would be just fine - either way. Lots & tons of treadle lathes were built from heavy solid stock, quartersawn when they could get it & whatever rolled out of the mill when they couldn't.

It's all a matter of how far you want to go with it. A solid piece of spruce 4x4 from the lumberyard would probably be entirely fine for it (interestingly, at least in my neck of the woods a spruce 4x4 almost always surrounds the heart of the tree).

Next better would be a pair of honest douglas fir 2x4s, growth rings random.

Next better would be the same 2x4s with mirrored growth rings.

Next better would be three 5/4s, random growth rings.

Next better alternating growth rings.

Next better four 4/4s, random.

Next better four 4/4s, alternating.

...and so on. But really... if a spruce 4x4 doesn't do it sufficiently well, I'd be surprised.

[cabinetman]

I agree with what mark said. Just a suggestion if you are gluing multiples, make sure you don't get any of the lams skidding out of place. Once clamped up they could slip.

[rblusthaus]

Thanks guys. I agree that spruce, either from laminating 2x4 or one 4X4 would be strong enough. However, I am also thinking of the finished look and I want the ability to break it down so that it could be moved and reassembled at, lets say, a renaissance fair or at a local school. For this reason I want to stick with a hard wood. The extra weight of the hard wood will be beneficial as well, although I could use sand bags.

I am thinking oak with the ways being made from maple, so I will have a nice color contrast. Maple and walnut would also work. We will see what the mill has when I go to purchase.