laminate stem in strips versus pieces

[chuckt]

I am getting close to the time I will be fabricating a new stem for my 1950 CC Express Cruiser 30' I am restoring. From browsing other threads, it looks like most folks who laminate one do so by bending thin strips (1/8 in). In his book, Reuel Parker seems to be gluing larger peices together. I've made a rough drawing (obviously not to scale) of what I see are the options. "A" is a bad drawing of 1/8" strips bent and epoxied. "B" and "C" would use thicker pieces (4/4 probably) and would require cutting the curve using a bandsaw. I am not adept at bandsaw work and would be cutting with a 3/4 HP delta. So, my concerns with B and C are my ability to cut the curve with the bandsaw and having a stem not as strong as option A. My concerns with A are wasting wood ripping 1/8 strips, using more epoxy, and taking more time to get it done. I'll be using fir. What y'all think?

http://i571.photobucket.com/albums/ss151/cmeke0870/work%20begins/laminationoptions.jpg

[outofthenorm]

Option A will likely give you the strongest stem, so IMO it should be top of the list. You won't need to go as thin as 1/8 with the fir. If it's straight grain with minimum run-out, you should be able to bend 1/4 or even 5/16. Plus keep in mind that you could steam and pre-bend even thicker pieces on a form, then glue up when they are dry and set.

- Norm

[chuckt]

Obviously the number of layers pictured is not accurate. I would take quite a few 1/8 layers to build up to the 3-4 in depth and 4-6 layers of 3/4 or 4/4.

[chuckt]

I always wanted to steam bend, even though that will mean I need to build a steamer. Maybe liking that idea.

[Breakaway]

I'll let experienced builders comment on the merits of A and B. But the solid wood "C" choice I would'nt consider at all.

[chuckt]

"C" is meant to be a depiction of 3/4 pieces laminated parallel in a big stack and then the curves and shapes cut out on the bandsaw and with a handsaw. I wont be cutting it out of a solid single piece of wood (or several big pieces bolted together as is the original piece)--am definitely sold on laminating the stem.

[outofthenorm]

I agree that Option C sucks. You'd end up with exposed end grain everywhere.

Building a steam set up is easy. Nothing very fancy is required. This is what I built to steam some white oak last Summer. Steam source was a corn-pot on a gas camping stove.

http://pic90.picturetrail.com/VOL2330/11517070/22665443/383020726.jpg

- Norm

[chuckt]

"open grain everywhere" Duh-Why didn't I think about that. I am glad you guys are here--I need to start a thread on the whole project so ya'll can keep an eye on me and keep me from doing stupid stuff like option C.

I'm excited about steam bending--probably going with that plan. I've got Danenburg's book and I think he has good stuff on steam bending--I'll review it tonight.

[outofthenorm]

-I need to start a thread on the whole project

Well, yaaaaaaah! With pics, of course.;)

[Pacific Woody]

I've built a number of stems using anything from 1/8" strips (for canoes which only require one and a half to two inch thick stems) up to 1/4" strips for more robust stems. In my experience thinner means no need to steam which is nice, but more layers to build up. Build a form, laminate with epoxy, and use lots of clamps. Bomb proof and you can still shape it with hand tools.

[Bruce Hooke]

I note that you plan to use fir. I have never tried to steam bend fir but my understanding is that it does not steam bend very well at all. So, I would run a quick test before you count on going that route.

I am also a bit cautious now about steam bending and then laminating. I tried that once with white oak and epoxy and the laminates could be pulled apart by hand after the epoxy cured. This may well just have been a white oak issue but even so I approach steam bending and then gluing with caution.

Enough fir to make 1/8" laminates for a stem does not take that much wood. I think I would just cut the laminates thin enough to bend without steam. You can work out the right thickness for the laminates by cutting a test laminate and seeing how hard it is to bend around the form. Remember, when you actually do the glue up you will be bending a whole stack of laminates all slippery with glue so you want the single laminate to be pretty easy to bend around the form.

[WI-Tom]

I just built a stem laminated from 1/8" mahogany strips; I thought it would be much more of a mess than it was--it ended up being quite simple.

Tom

[wizbang 13]

sometimes you can start with thin lams and mill them thicker as you progress. The purpose of the knee is to attach the stem to the keel so you may be able to taper the lams out and eliminate the knee. Are you going to lam in place or waste a bunch of time and materials by making the stem on a bench? (kick me now)

[chuckt]

Hmmm. Okay thanks for the advice. Maybe not steaming then. Is it really necessary to glue them all at the same time? I envisioned doing part of it then adding more layers later. Also, I didn't really think about doing it in place. I'll have to pull my thinking chair up to the bow and contemplate that. Hmmmm. I really like that the boat is about 20 steps from my side door--very convenient.

[paladin]

The thinner strips will eliminate springback, will be easier to bend, no need to do them all at once. Just do 3-4-5 or so as you want, clamp them lightly so as to not squeeze out the resin, and have fun. Lay it up on mylar so that it doesn't stick to the bench.

[wizbang 13]

there is no reason you have to do it all at once. Doing it in place can save lots of time. Trouble is ofcourse no caulking rabbit. Glued in place means plank ends get glued in place too . ( that does not bother me, I think it's better) Width of lams changes to place them closer to plank. One can chop away half the stem (inside or outside), laminate it, then chop away the other half and finish laminating. It's far from conventional or traditional but you are already moving away from that, no?

[chuckt]

To be honset wizbang, I cant picture what you are describing. I'm sure taht's because I have no experience doing this. I cant picture doing it w/o a rabbet for the planking. Anyone have a suggestion of a book that goes through this process or maybe somehting on line. Its not in any book I have or anywhere i can find on th eweb.

[outofthenorm]

Laminating in place is a fine idea - so long as there is something to laminate against. Can't do it in thin air, so you're going to be building a form anyway. Don't give up on the steaming idea so fast. Take your time and consider all possibilities before you jump in.

Take note that "DF doesn't steam very well" does not mean it doesn't bend with steam - it just doesn't like it as much as some other woods. If you were talking about bending 4x4 stock, you'd be right to hesitate, but that's not the case. And steaming has absolutely no impact on the gluability of the wood. The anecdote mentioned above is most likely a result of the combination of white oak and epoxy, a well documented issue that has nothing to do with DF.

An important first step is to assess your stock and determine if it is suitable for bending at all. Try it dry, try it dripping wet and maybe try it steamed and see what happens at various thicknesses. You can build a form in an hour or two.

Spend a few days experimenting and you won't regret it. Make snap decisions and you will.

- Norm

[wizbang 13]

I like that, "snap" decisions. Any snapping going on, definately rip thinner.

[Bruce Hooke]

Take note that "DF doesn't steam very well" does not mean it doesn't bend with steam - it just doesn't like it as much as some other woods. If you were talking about bending 4x4 stock, you'd be right to hesitate, but that's not the case. And steaming has absolutely no impact on the gluability of the wood. The anecdote mentioned above is most likely a result of the combination of white oak and epoxy, a well documented issue that has nothing to do with DF.

Given how "dramatic" the problem I experienced was (I was able to pry the laminates apart with just gentle hand pressure) I don't think this was just the much discussed white-oak epoxy issue as I have never heard of that issue resulting in such a total and immediate failure. So, I would say the problem I experienced clearly proves that "steaming has absolutely no impact on the gluability of the wood" is almost certainly false at least in some situations. However, my suspicion is that the problem I encountered was a result of the combination of steam, white oak and epoxy, which would not apply if the wood is douglas fir rather than white oak.

None-the-less, given that experience, I approach ideas about steaming and then gluing more cautiously. If nothing else, before gluing up something that has been steamed I rough up the surface well with course sandpaper. With that precaution added into the process I would feel comfortable steaming and then gluing fir, assuming steam has enough effect on fir to make the whole process worth the trouble.

On the count...I cannot remember ever having tried to steam douglas fir. I know I have run into some woods that steam seemed to have absolutely NO effect on. So, I would just say do some testing before committing to the steaming route. A quick test would be quite easy -- just rig something up on the stove since you just need to test a small piece of wood to get an idea of how it will behave. One approach would be to put the piece of wood across the top of a pot of boiling water (resting on the edges of the pot), slap a lid on it and let it sit over the boiling water for 10-15 minutes or so. Just make sure the ends of the piece of wood hanging over the edges of the pot don't get so hot they start scorching.

[willmarsh3]

You can set up a simple jig for laminating a curved piece like this:

http://www.willmarsh3.net/el/elver092103.html

Just use a bunch of T shaped pieces fastened to a sheet of cheap plywood with drywall screws. Then use aluminum foil to keep the piece from sticking to the jig. It can be reused.

I steamed an laminated 1/16 mahogany using epoxy without problems.

I've also steamed and laminated 1/8 southern yellow pine (any one of 4 species) without problems. I left the pieces rough after ripping them on a table saw for to get a good key for the epoxy.

I think clear doug fir with epoxy would work fine after all I built a mast of doug fir with West epoxy and it's holding up fine.

The other question is how does this compare to how the stem was originaly built?

[outofthenorm]

Bruce, we are actually in agreement and I defer to your experience on these things. If it was my project, I would experiment to see what thickness of lam would work without too much stress and glue it up dry from that, probably with rescorcinal (SP?).

I've had occasion to steam fir and had some success - the result was about the same as soaking it for 24 hours. It became somewhat pliable - not tie-it-in-a-knot style, but workable enough to do a stem.

- Norm

[chuckt]

Will, just fyi, the stem was orginally several pieces bolted together.

http://i571.photobucket.com/albums/ss151/cmeke0870/work%20begins/IMG00078-20100220-1632.jpg

[Breakaway]

The plans for the rubrails for the sharpie I'm building called for 1.5" x 1/2" ...I decided to use a rabbet to cover the end grain at the sheer of the plywood planking and so ended up trying to bend, essentially, 3/4" DF. Dry, the stuff didnt want to make the bend/slight twist aft. So I soaked em, bent em easy as pie, left them in place until dry. Then I removed and glued them back on. No probs. Isnt this basically the same question you have, granted with a tougher bend and using more pieces?
http://4.bp.blogspot.com/_81BJ7UlL2qo/SeVMKbfzFBI/AAAAAAAAAEE/F_jfCwqs_yc/s1600/P4140008.JPG

[chuckt]

Yes breakaway--thanks. That gives me some confidence. I'll be starting a thread on the whole project soon. I want to make some more progress before I do. As I cannot take time off from my real job and farm maintenance, my progress is a little bit at a time. After going back to the Gougeon brothers book, I probably will be doing what they describe in chapter 19 (5th ed.) which is basically laminating thicker where there is little bend and thinner where there is, eliminating the rabbetts and basically planeing things to the proper shape and "capping" the endgrain.