Total noob with glass bow riser question

[takefive]

A couple of years ago I tried to make the Binghams 62" hybrid.  I managed to wreck it during the glue up, but reordered the glass and lams from Kenny in case I wanted to try it again.
This time I'm thinking about making the 18" riser an I beam of bubinga, curly hard maple, and bubinga.  I also have a piece of brown phenolic I can add if necessary.  I'd like to figure it so the maple just shows through the sight window, but I don't know how far I can safely cut the shelf in.  Binghams recommends just enough for the arrow to sit on, but I've seen that many of you guys go quite a bit deeper.
Any suggestions or thoughts are appreciated!

 

[macbow]

The phenolic is the key. If you want a deep shelf then the Ibeam and phenolic will give the strength to cut to or even past center of mass.

I'd not trust a,all wood riser cut to center otherwise.

[takefive]

Thanks macbow.  If I can cut it close to center with the I beam and phenolic I'd be happy.

[Roy from Pa]

Yup you're a noob for sure..  

[takefive]

I knew I should have said "helpful suggestions" instead of "any suggestions" just in case you chimed in, Roy.   :p

[BigJim]

With a laminated longbow and bubinga riser (no i-beam), you would be safe finishing sight window to center cut not shot.
Bubinga is much tougher than the maple so you are actually weakening the riser. Yes, laminating will add strength if there was an inherent issue with solid riser.
You can add the phenolic for strength, but as long as you don't over grind grip or end up with excessively heavy bow, I would leave that out. Even with the phenolic, I wouldn't venture past center cut.

As long as your wood is dry (both mentioned woods are likely kiln dried) you won't likely have an issue adding the phenolic.

good luck, BigJim

[takefive]

Thanks for the advice BigJim.  I have the pieces cut for the riser.  Maybe I'll substitute jatoba for the maple section.  Either way, I won't cut it past center.  It's a 45# bow.