Gluing in Multilam Reflex

[Tommy D]

Is there any advantage to gluing up multilams in stages - ie. On a trilam for example glue in an inch of reflex, let the glue cure and then blue in another inch of reflex for a total of say 2 inches. I remember reading something about this in one of the TBB’s?

[avcase]

You might find an advantage if you glued the core and belly lam in 2-3 inches of Deflex, then glued this to the backing laminate in 1-2” reflex. The bow will probably spring back to almost zero deflex after adding the backing layer, but this can help offset some amount of the compression stresses on the bow belly.

Alan

[DC]

Super Perry!!

[bownarra]

You might find an advantage if you glued the core and belly lam in 2-3 inches of Deflex, then glued this to the backing laminate in 1-2” reflex. The bow will probably spring back to almost zero deflex after adding the backing layer, but this can help offset some amount of the compression stresses on the bow belly.

Alan

Yes that is the way to do it.

[Tommy D]

 Thanks - will give that a go. Is it a figment if my imagination that somewhere I read (I think TBB) that “Perry Reflex” (don’t all jump on me for using the term!) worked best if each subsequent lam Reflexed the previous lay up. Some sort of multiplier effect.

[Pat B]

I think there is a reference in TBBI, maybe in the "Performance..." chapter about different degrees of deflex/reflex added to different pairs of lams in a glue up.

[PatM]

That was mostly speculative.

 Chris Boyton used to make a bow with a double hickory backing strip glued up in a complete circle  and then  glued that to two other layers in a a straighter form.

[mmattockx]

I remember reading something about this in one of the TBB’s?

I think there is a reference in TBBI, maybe in the "Performance..." chapter

The section on Perry Reflex is in TBB V.3 under the "Bows of the World' chapter, page 91.


Mark

[Pat B]

My mistake. The paragraph I was referring to is the paragraph above the section about Perry reflex on page 91.

[Tommy D]

That was mostly speculative.

 Chris Boyton used to make a bow with a double hickory backing strip glued up in a complete circle  and then  glued that to two other layers in a a straighter form.

When you say “speculative” - do you mean that what they were describing in that section of TBB was more theoretical than known fact? I am assuming it had some benefit to Chris Boyton what he was doing or is it really not worth it?

[willie]

Perry reflex is generally recognized as an improvement. There is speculation about how/why it works.

One could possibly build two identical bows, one with perry reflex, and one without, to prove it works. But I am not sure how that would be done.

[RyanY]

Can’t believe I haven’t heard of gluing up lams separately to change the forces they exert on each other. 

[Tommy D]

Can’t believe I haven’t heard of gluing up lams separately to change the forces they exert on each other. 

Can’t tell if that’s sarcasm or not!

Unfortunately I don’t have my copy of TBB with me - but I remember some theory that gluing you lams took the stresses away from the wood and more to the glue line?

[Tommy D]

That was mostly speculative.

 Chris Boyton used to make a bow with a double hickory backing strip glued up in a complete circle  and then  glued that to two other layers in a a straighter form.

Been thinking about this ... this seems to be the right way to go if I have a tapered core, a bamboo back and an Ipe belly ... was thinking of gluing the core and bamboo together in reflex and then pulling some of this into a more R/D shape the second round of gluing with a belly lam?

Thoughts?

[willie]

I recall Dan Perry commenting in a thread a long time back, that he may have seen the most advantage to having a belly of 2/3 thickness prestressed and glued to the thinner backing. If I understand what is happening correctly, then I would be more inclined to try Alans suggestion.