Stem Laminating

[Alan Peck]

I am trying to laminate a stem using 1/4" laminations as called for on the plans.

I don't have access to any green wood and have tried both air dried white oak and lumberyard fir.

Neither one of them want's to take the necessary bend without breaking. Would it be ok to soak them for a few days and then bend them into the jig. Since they will be wet, I was thinking of letting them dry for a few weeks before trying to apply the glue.

Does this make sense or am I missing something?

Thanks

[Thorne]

What boat / plans? What sort of form are you bending onto, and what sort of mechanical system is creating the bend?

From what I understand the issue isn't moisture but heat -- the moisture in the steaming process just carries and 'stores' (for time measured in seconds) the heat -- which is what makes the wood bend.

[David G]

Mr. Peck,

There are a variety of ways to accomplish your task. You could, indeed, do as you propose. You could also start with thinner strips, and use more of them. That would avoid the drying time. You could build yourself a steam box, and steam your strips before clamping to the form. That would also take more time upfront, but less drying time at the end. That's just the most common bunch of approaches. Again, your proposed sequence will very likely work (I only hedge because you don't tell us the rest of the details: size of strips, other than thickness; length of stem; radius of the bend at its tightest; etc.).

Good Luck.


"The only real good place to buy lumber is at a store where the lumber has already been cut, and attached together..." -- Dave Barry

[Canoez]

Depending on your radius of bend, thinner laminations should work OK dry, but with your choice of adhesive (aliphatic glue, polyurethane glue or epoxy - remember cautions for oak/epoxy)

We bend stems for the Wee Lassie dry in about 3/32" thickness with just the glue and do well. You could wet them and let them dry clamped in the curve, too, but let them dry very well before bonding.

With thicker pieces you could boil or steam them before bending, but again, let them dry thoroughly.

When you laminate pieces of stock, try to keep the grain running the same direction and keep the strips the way they came off the original board - this is helpful cosmetically and it also helps to make beveling the strip easier without a reversal of grain direction to cause tear-outs.

What is the form and how are you holding strips down?

[JimD]

I've done this sort of thing many times with fir. Provided its not a tight bend, soak the strips in water for several days. Bend them over the jig and clamp in place. Allow several more days for the strips to dry. Glue them up and clamp back onto the jig until the epoxy cures. The fir needs to have very straight grain. It doesn't like to bend and will break if there is much grain run out.

[paladin]

Depending on the size of the member/boat, it may be nearly as economical to purchase a piece of mahogany, slice it up, and laminate it as the stem.....or if you use fir, just make it in 1/8th inch slices and flip every other piece....

[Paul Eaton]

The other option is to laminate in the other plane ie have the glue line stem to stern. I did this with my plumb bow steam launch - as I recall 5 or 6 laminations about 3/4 inch wide. 3 pieces of timber per lamination. As long as the joins are sufficiently different it is plenty strong enough. Bud McIntosh mentions it in his book.

[eastern270]

I laminated my stem and keel entirely out of 2-1/2" wide strips of 1/4" okuome plywood . My boat has a plumb bow so the I have almost a 90 degree curve. I had very,very minimal spring back after unclamping. This way seems to have work out great for me so far.

[Boatsmith]

Just glued up the stem for Oughtred's Guillemot. Used 3/16" laminations because when we tried 1/4", they broke. Another thing to keep in mind is that the less runout in the grain the less likely to split. Also if you think of your individual laminations as planks, you want to use flat grain planks as opposed to vertical grain or quarter sawn planks. They will bend a lot easier that way.Also bending them over the course of a day or two will sometimes help. But I personally don't like this method because I don't like to wait for a day or to to find out, oops it doesen't work, David

[Martin Nelson]

You might try soaking the strips for a few days, then using a steam box. That has worked for me in the past. You could steam the wood twice as long without soaking, but soaking first seems to be better. You will need a steam box when you steam the ribs, so building one now won't set you back any in the building process.

[Canoeyawl]

If the laminations are so thick that they are breaking, you will surely have glue starvation caused by the extreme pressure at the max radius. Steaming then bending over the form, waiting a few days to dry, and then gluing is acceptable. Soaking is overrated. I think you need much thinner laminations - some wood is very stiff even in the same species.
Any way that you do it I would suggest you create a test piece and test it to destruction then cut it open and examine for glue starvation. This is your stem, a most critical part…

[Rich VanValkenburg]

When laminating the new frames for Sonja. I used air-dried White Oak cut and planed to 1/4" x 1". I laid these over a large boiling pot and put a lid over them, covering the critical bend area. The pot had only an inch of water. This comes to a boil on the stove pretty quickly and once there was steam I let them sit there 15 minutes. They bent over a pattern easily without breaking and I left them clamped to the pattern overnight to dry, then glued using Weldwood plastic resin or resorcinol. Forget using epoxy. It didn't work as well at 1/4" using Douglas Fir for the Nutshells, so the laminates wound up being 1/8".