ELB Trilam question

[kevinsmith5]

I'm thinking of doing a white oak, hard maple, Ipe trilam. Maple core, white oak back, Ipe belly, 76", continuous taper from 1-1/4" x 8" handle to 1/2" tips and total length 78" (ntn @76"). My questions are if it was you how thick would you go on the Ipe and ae if you wanted 75-90 lbs? I usually use white oak as a 1/8" backing.

[toomanyknots]

1 1/4" is too wide I think for an ipe bow of this weight. You wanna go 1 1/8" wide at the handle, for glue up dimensions, and then you might wanna take that down a bit too during tiller, etc.

- 1/8" thick backing
- 1/4" maple core, tapering to somewhere in between 3/32" and an 1/8" or so at the ends.
- 1/2" to 9/16" ipe belly.

This is based on my notes from making similar bows at 75" or so nock to nock. A full inch thickness with these dimensions can easily give you 120# @ 32", so I think 7/8" to 15/16" should be more than enough meat for you. I think it is important to taper your core with softer cores such as maple as well, only because you can get set in the tips if you don't. Although I am pretty bad at remembering to taper them myself,  .

[mikekeswick]

Yep 1 1/4 is too wide. Ok for glue-up but the finished bow definately won't need to be wider than 1 inch at the handle.
I personally would go for a 1/4 backing and an 1/8th core...then no need to taper it  but that's really just personal preference...although i'm not 100% on it but I think thicker backings work well with ipe and other very dense woods.
Toomany's advice is spot on.

[adb]

I'd go 1 1/8" wide at the handle, 1" total depth thickness. Continuous taper from a 4" handle to 1/2" tips and continuous belly taper from 1" thick at grip to 1/2" at tips. I'd also make the backing 1/4" and the core 1/8". The core should be compression wood so maple isn't your best choice, but it should be OK. Make your tiller just a sniff elliptical, and it'll be a sweet shooter.

Here's my interpretation of good tiller for a long tri-lam ELB...

[kevinsmith5]

Is that core ipe?

[adb]

Yes. Maple back, ipe core, osage belly.

[toomanyknots]

Nice looking bow, great tiller.

[Bowman]

My experience is that hickory is a better choice in the back. I use white oak in the belly, but Ipe in the belly is perfect. Maple is a good choice in the core. Good luck. :-)

[adb]

Hickory is a good choice on the back. So is maple. I've made maple backed yew warbows up to 120#, so maple is plenty good in tension.

[toomanyknots]

Hickory is a good choice on the back. So is maple. I've made maple backed yew warbows up to 120#, so maple is plenty good in tension.

I like maple a lot too because it is lighter than hickory. If I wanna really light weight quick shooting bow, I find maple for the backing works great.

[Bowman]

Maybe maple is good. But ash is good in tension too. I use hickory and ash. Maybe American maple is better than european. Hickory was the choice number one in victorian longbows  from the 18 th century. :-)

[Hamish]

 I haven't had a great deal of luck with rock maple for backing. Out of 4 attempts 2 were good. Those two I meticulously followed the grain, they were done by hand, not from a saw or planer, like I would use for hickory. The one's I tried like hickory sawn slats both blew on me at full draw, despite being exercised to full draw many times.They had very straight grain too.
It could've just been a bad board for the ones that blew, because the hand worked ones that followed the grain came from a different board.
The really good thing about rock maple was it gave significantly less stringfollow than hickory.
Maple obviously works as a backing. (Top job adb)I just think the grain has to be dead straight, or maybe even taken down to a growth ring when you get to really narrow bows like you do when you use ipe.
Haven't used Oak as a backing yet, but said to be on par with hickory if you use US white oak and its straight grained.

[toomanyknots]

You might of just got a bad piece. I think it happens sometimes. I bought a bunch of hickory once, perfectly straight grained. And it would not make a bow for nothing. Every little piece broke. It is now barbeque wood.

[adb]

I've had great luck with maple as backing and self flatbows. ELBs, laminated flatbows, and laminated warbows... very few failures. Maple is actually one of my favourite woods. Canadian maple, mind you! Hard sugar maple.

[kevinsmith5]

For reference here is the list of woods I have or have access to for sure through my local wood lot that I know of-
Northern hard maple
Silver (soft) maple
Ipe
Jatoba
Purple Heart
Ash
Hickory
White oak
Red oak
Ipe
Greenheart
Locust (they aren't sure on variety and I've no experience)

He has been trying to get Osage for about 6 months but can't get any of decent length (pen blanks basically).