Tri Lam Question

[Dan Landis]

Finally getting ready to start on a bamboo backed tri lam.  Is there any problem with using hackberry as a core wood?  The belly will be osage, and the bow will be 64" tip to tip. and hoping to get in the low 50's for weight.  I plan to cut up some staves for the hackberry and osage on the table saw.  Any suggestions for a starting width using these woods?

[Bowjunkie]

I haven't used Hackberry as a center lam, but it should work. Any wood that will make a selfbow will work.

I'd cut it out at about 1 3/8", but guess it will end up closer to 1 1/4" finished width, maybe even less. It depends on your other design factors.

[Dan Landis]

Thanks Jeff.  I'm sort of following Roy's design used on the last build along he posted.  Don't know how well I'll be able to taper the core using the table saw though.  I'll get it as close as I can and remove more of the belly wood to tiller.

[Roy from Pa]

Dan if ya like, send me your core lams and I'll taper them for you for nutten. You just pay the shipping both ways. It won't take but 15 minutes to taper them and I owe you a favor for the material ya sent me a while back.

[Dan Landis]

Roy, thanks for the offer, may take you up on it.  I have to get something ripped out first, at this point all I have is some not so straight staves.  You don't owe me anything by the way.

[LittleBen]

Dan if you are careful you can rip tapered lams on the table saw. Canopyboy and I probably cut 100 lams that way in his shop. If you've got a well tuned saw you can get some pretty surprising accuracy.

First we made a nice think sled (make it thick because it's going to ride on it's edge).

[Dan Landis]

LittleBen, working on making the sled now, hopefully will get something I can use.

[Dan Landis]

Here's where I'm at so far.  Have my osage cut to 5/16 thick and Z spliced, have my hackberry center lams tapered from 1/4" to 1/8" and Z spliced, and my bamboo cut to the bow profile.  I noticed when I cut the bamboo to profile that it is thicker on one side than another.  How important is it that they be even from one side to another, or can this be corrected when tillering by removing more wood from my belly lam?  I have no way to correct the bamboo other than a scraper or a hand held belt sander.

[Roy from Pa]

You want the sides equal. Use a small hand plane to remove material from the thicker side. Then use a toothing plane to even things up. Being careful, the belt sander would suffice. You could mount the belt sander in a vice and run the boo across it that way for better control.

You want the boo 1/8th thick at the riser, tapered to 1/16th at the tips.

[Dan Landis]

Thanks Roy.  It is tapered end to end, but didn't notice the side to side difference until I cut it to profile, then it became very noticeable.  I'll see what I can do.

[Roy from Pa]

After the boo is cut to profile, I thin it down and taper it on the 4 foot edge belt sander. Then finish it up with a toothing plane.

[Dan Landis]

Sure wish I had a 4 foot belt sander and a toothing plane.          I got it looking pretty good with my 18" belt sander clamped in my vise as you suggested, and a fine toothed saw-zal blade.  As soon as I get the curves bent in the ends I think I'll be ready for glue up.

[Roy from Pa]

Don't forget to pad the boo so the clamps don't indent it, I also lay a thin lam on the belly side to protect it. Don't forget to mark the limbs where the mid limb posts will be. I drill 2 small holes in the handle grip area and 2 holes on each side of the tips for tooth picks to keep the boo aligned at glue up. I do a dry layup with a string to get everything straight then clamp it down and drill the holes. I also wrap tape around the mid limbs to hold them straight. Just don't tape over your mid limb posts marks. That has happened.  LOL

[Dan Landis]

Just finished making a batch of pads.  I ground the curvature of the boo into the bottom of each one with the nose of the belt sander.

[Roy from Pa]

Atta boy....

[Dan Landis]

Glue up is complete, now for the waiting & hoping all is well when the clamps come off tomorrow evening.  

[LittleBen]

Can't wait. Post some pictures for God sake.

[Roy from Pa]

What Ben said...  

[Dan Landis]

Sorry for the time lapse, been out of town for two days installing a new floor for my daughter.

Here is where I'm at so far.
Glue up

unclamped.


Handle glue up


Profiled


Handle rough cut


Now, where do I go from here.  At this point I can barely get the limbs to flex when floor tillering.

[Roy from Pa]

Trap the back, lower the belly facets, and radius the belly center.