Deflex and then Reflex

[NTD]

Oneeye sent me some laminations for a tril lam bow.  I'm thinking about gluing them up this weekend.  While pondering what I was going to build I had an idea.  I'm sure this theory is nothing new so I'm giving it to you guys to tell me whether it would work, be worth it, etc.  Would there be any benefit to gluing the midlam to the core first into deflex and then when I glue on the backing glue in a normal r/d shape?  From my limited understanding of how all this works it would allow the bow to store even more energy?  Say my final profile I'm looking for 3" relfex tips.  If the core and midlam are first deflexed 1" and then once the backing is glued on I pull them into a 3" reflex, then the final reflex would actually be 4", in my pea brain resulting in more energy storage.  Is that clear as mud     Maybe   Thanks for any input.

[Cameroo]

Hey Nate.

I'm not sure that I understand what you're saying, but the way my pea brain works, I would think that the deflex would subtract from the reflex.  That is, 1 inch of deflex and three inches reflex would net you 2 inches of reflex.  Er what?

If you wanted to end up with 3 inches of reflex, with 1 inch of deflex in the handle, you'd have to reflex the tips 4 inches wouldn't you?

[Ryano]

Nate, when I glue up a tri-lam bow I glue the belly to the core first in reflex/deflex then I add the bamboo backing and glue it on with more induced reflex. I think this helps the bow hold its unstrung profile better.

[NTD]

Thanks for that Ryan. 

Cam, by your response I see that I did make it as clear as mud   IF you have seen how Marc St. Louis builds his R/D's he glues in defelx at the handle splice.  This results in the tips being deflex about 3", at least it did on the one I built.  When you apply your backing and pull these limbs to their final reflex shape they have to travel that 3" of deflex to be even plane and then the additional distance for final refelx shape.  So if the final profile has 3" of reflex you actually have 6" of reflex...does that make sense?  I was just wondering if there would be benefit to applying the same concept in a trilam.  Instead of spliced in defelx I start with glued in deflex which would require the limbs to travel further back to get my desired R/D profile...

[NTD]

120+ views....am I not making sense to anyone

[NTD]

Thanks Scott!  What you are saying will happen is exactly what I figured would happen.  I just seem to think favoring the belly that way might be a good thing.  But I don't know that so figured we could kick it around here.

[Justin Snyder]

You will loose your reflex if you do it that way.

What kind of wood? You can glue the belly and core into high reflex profile then pull some reflex out if you want to protect the back and stress the belly more. You can glue the belly and core with less reflex then add more to increase stress on the backing. It really depends of the wood you are using though. If you are doing Ipe and Boo I wouldn't worry about the back or belly, but if you are using a wood that frets or a backing that will splinter easier, I would change the profile to fit the wood.

[NTD]

Thanks Justin!  It'll be osage belly, bubinga midlam, and bamboo back.  Think I'll do like you and Ryano suggested.  Glue moderate first and then increase the reflex with the backing.  Thanks guys, just a thought experiment...

[NTD]

Now you're exceeding my mental faculties    That does make sense.  I was just thinking that pulling strain away from belly and putting it in the tension strong boo might could be a good thing.  Less belly strain is less set, right?  And I figured the further the limbs traveled backwards the more energy they would store, But if this would pull out the reflex as Justin suggested than I guess my theory doesn't matter.  I sure wish I had the time and materials willing to sacrifice to this and just give it a try. 

[Pat B]

Nate in book I of the TBB series the chapter on performance(I think) and just before the part about Perry Reflex the author describes a glue up process where you do what you are talking about but with different degrees of reflex with each lam added. If you have TBBI look it up.

[NTD]

Thanks Pat.  Yeah it's TBB3 that has a short discussion about that.  But Tim is so unenthusiastic about laminates that the discussion is hardly illuminating.  I'm more curious as to what reflexing a deflexed lam would do.  I think it would add at least 20lbs   But in all seriousness lets look at it another way.  If you had a naturally deflexed of 1 1/2" single lam of osage and you glued up 3" of relfex ultimately being 4 1 1/2" of total reflex, wouldn't that store more energy than a straight core that was reflexed 3"?  I guess I'm justing looking to duplicate that effect artificially with a third lamination.

[NTD]

That being said I'm not going to waste that purty set of lams on an experiment.  Maybe later

[Pat B]

If you have the time, initiative and materials give it a try and report back with your results.  
  You beat me to it! 

[NTD]

Pat,

If I can get my jointer dialed in and have the ability to make more lams myself I will definitely give this a try.  And will certainly report the results here

[NTD]

Hey Nate.

If you wanted to end up with 3 inches of reflex, with 1 inch of deflex in the handle, you'd have to reflex the tips 4 inches wouldn't you?

I was just reading back thorugh this thread and yes Cam you are right, and that was my whole goal   to get 3inches the limbs would have to be reflexed 4" in my thinking resulting in more stored energy without as radical a profile  

I wish Badger would weigh in on this, something makes me think he's already tried it....