Trilam question

[Gordon]

When building a trilam bow I assume that you need to taper the powerlam. But how do you do that and still have an even surface to glue on the belly - in particular where the tapers come together at the handle? I'm sure the answer is obvious and I'm just being dense 

[Jesse]

I am no expert but on the one I made everything was tapered. The belly was the thickest to leave room for tillering. The power lam I tapered by eye on my belt sander. I used a thin piece and when it was done it was so flexible when you put the stretch clamps on it doesnt have a problem lying flat. I didnt have any sharp angles. A gradual taper to the tips and I didnt have any problem.   Someone who has built more will have better advice.
                                            Jesse

[Jbell]

 Gordon, I have never made a tri-lam before(on my list) on my belly slats I taper about 1/8" for a r/d and a bit more than that for a recurve. My method may not be the best or the fastest but all I do is mark a spot an 1/8" on the end of the slat(bothsides) then with a long straight edge or sometimes with fineline tape I make a line all the way to where the fades will be. I do this by hand with a file then finish up with 80 grit on a longboard, just follow the line. The taper near the handle is so gradual that your glue lines will be just fine, no problems with my method so far. I would also taper the belly lam, that will give it a nice bend in your caul.
 My 1/8" is just an example, on a tri-lam you may wish to taper less than that, since you will have thinner slats.

  Hope you find the answer you are looking for.

[Gordon]

Justin, that does help. Thank you!

[Gordon]

I guess what I was refering to as a "powerlam" is really a centerlam. Any thoughts on tapering a centerlam?

[Justin Snyder]

Because there is so little stress on such a thin piece you can bend them without worrying about failure.  If I taper at all I just pre-tiller them and make sure they are bending the way I want them to.  I don't usually worry about taper since the belly and back are doing the majority of the work. As for power lam, I sometimes have a center lam that is 1/2" in the center and tapers to 1/4" at the fades then stays 1/4" to the tips.  Justin

[Gordon]

That makes sense Justin. Thank you.

[Ryano]

Gordon, I never made one but I know in my brother's tri lam bamboo bows the center lam is parallel not taper. He pre tapers the boo belly and backing before glue up. They come off the form semi-tillered......It just takes some trial and error to come up with a good combo.....

[Rich Saffold]

 GordonI don't taper the center lam, but keep it fairly thin and glue it up with the backing in a subtle reflex  or reflex/deflex curve. I then amplify the same curve when I glue on the pretillered belly section.

Rich

[Gordon]

Thank you for the explanation Rich. Why do you glue the centerlam and belly in separate steps?

[tradbowr]

Gordan
     Use the Perry method.  Put the tappered side to back of bow.