Crossbow Core Cwestion :)

[Del the cat]

I took the shoot-through prod back to the point where it lifted a splinter on the bamboo back.
Over all the prod was a bit too strong and I'd narrowed the limbs (especially the back).
Anyhow it did pretty well getting to 120# at 10" with a 3" brace (all measured from the belly)
I'm going to build the mkII and I'm wondering what the best core wood choice would be.
I have some Ash, Hickory, Hazel, Lemonwood, and some unknown slat of brown-yellow wood
The original prod was Hickory core.
The Mkii will be a tad longer and be built with 1" of deflex, it will be a tad thinner but not so narrow on the back as the final state of the mk1
I'm fancying the Lemonwood as I have a 1" square length of it and it's not very exciting for making longbows.
Any suggests for best core wood greatly appreciated.
Del
PS. I subsequently planed off some of the boo to remove the splinter and got it back to 90# at 13" when it started splintering again, but it had a lovely full curve.
Pics show max draw and the braced bow (looking rather elegant) before failure.

[Marc St Louis]

So where did it splinter?

[Del the cat]

So where did it splinter?

Mid limb at a node which I'd prob' taken down a bit flat, and also narrowed the limbs rather a lot to try and loose some of the excess weight.
Pics on this blog entry:-
https://bowyersdiary.blogspot.co.uk/2017/11/prod-failure-mode.html
I'm re-working this prod by planing down most of the boo, splicing on 1" extra to each tip and the putting a new thin boo back on it. That should teach me enough to get it right next time.
It will also allow me to try the prod mounting which I have planned
Del
PS It was rather a scruffy piece of boo which had the nodes quite close together, the new backing is from further up the boo and will have just one node mid limb on each limb.

[Marc St Louis]

The one that I made was sinew backed and it did not bend in the middle.  I made it so that it had pretty well zero brace height, have to bend the limbs a bit to get the string on though.  The prod was about 36" long and I had thought at the time to make another longer prod (in the low 40" range) using Bamboo and Ipe but never got around to it.  I can't find my draft of the article and the pics I took of it at the time but I still have the crossbow and took some pics of it

[Del the cat]

Cheers Marc, that's pretty cool
I like the shoot through as it allows the V low brace without the string riding over the top like low mounted prod designs.
See sketch of proposed mounting (hope it makes sense), the angle material is 1/4" Aluminium alloy and I'll have a leather strip between it and the bow (all edges will be rounded of course). Binding probably rawhide or rubber strapping for test purposes. Hopefully it will allow the whole bow to flex.
Del

[Marc St Louis]

That flexing might give you trouble Del.

The zero brace height allows for a longer power stroke but it presented its own problems, particularly with the bolt.  As it was it had a 15~16" power stroke.  With the longer prod I was going to try I figured at least a 20" power stroke.  I was using 1/2" diameter bolts made of HHB, they hit the target with force

[Del the cat]

Yeah, it's all the compromises that make it challenging
I'll report back one way or another.
Del