Lam Combo order

[Wolftrail]

I have Maple walnut and yew lams. Not using glass just wood. The maple lam is 3/16" walnut 3/16" and yew is 1/8".  What is the best order to glue these up in.

[Wolftrail]

So the thinner lam is always in the middle. Is yew stronger than Sugar maple in tension..?   :confused:

[LittleBen]

Maple backing definately.

[mikkekeswick]

1/8th could only really be the core. Maple is a great backing wood and walnut well...walnut makes a good core! I've made a few bows with walnut bellies and it is only just ok. The maples resistance to tension is a bit much for a walnut belly without trapping.
Personally I'd get some more maple for the belly and heat treat it before prepping it for glue up.

[fujimo]

yew makes a nice light core- but might be better served on the belly- but the issue with the thickness- as mike said.
its only the yews sapwood that is very tension strong- a milled heartwood lam would only be suitable in a compression environment.
so to answer your question- as Ben intimated... yew (heartwood) is not stronger in tension than a well cut piece of maple- all things being equal.
cheers
mate

[Wolftrail]

Thanks guys for some reason I thought Yew was maybe stronger because of it been just a notch below Osage in tension.

"The maples resistance to tension is a bit much for a walnut belly without trapping."  So frets would appear on the belly if using this combo.

"a milled heartwood lam would only be suitable in a compression environment."  Its heartwood.

On another note what if I used 3 or 2 yew lams on the belly side all tapered and forget the walnut totally. Using 2 yew lams and the maple it would end up been 7/16".  Maybe a shorter bow it would make 40# plus pounds which is my goal ultimately.
I have enough bows between 34# and 38#...   :(

[LittleBen]

Personally I think if you put a taper on the maple backing and walnut core, you could get away with a parallel 1/8" belly lam of yew.

You'd probably need to taper both from 3/16 to 1/16.

Depending on bow length and width 1/2" butt thickness should get you over 40# I would think, but yew is so soft and flexible it's hard to say. My guess is you'd know right after glue up thouh, and if it needed more weight you could add a second yew belly lam ...

[Wolftrail]

Thanks LBen.  Sounds good I think I will try that. This yew is quite hard more so than the walnut from what I can tell by cutting it.

[LittleBen]

Originally posted by Wolftrail:
Thanks LBen.  Sounds good I think I will try that. This yew is quite hard more so than the walnut from what I can tell by cutting it.

Should have just said flexible ... I get so used to working with ipe I lose perspective. Post some pics when you finish it!

[Wolftrail]

The progress so far is.
Did all the bulk of the grinding yesterday.  After doing that I eneded up with a total thickness of 7/16"  I guess I could always glue on a 1/8" maple backing strip on.  I have lots of length at 31 1/2"  where as my current bow I just completed; the limbs are 29 1/2" .
Not sure what I want to do at this point in time, finish this set of limbs for the current riser or make another riser.
Decisions decisions      
I have a big time dust and sawdust issue in the garage and its dangerously gross, getting to old for all this mess in my eyes, lungs and everywhere.    :mad:    
Thinking of slowing down this year maybe complete 2-3 more bows from now till September.

[fujimo]

i have found with yew under glass, you need to add 10% to the stack to get the same poundage.