Deflex and then Reflex

[oneeye]

I'll bet he has tried it.

[Badger]

      You guys are right, I did try it but I have no recollection of how it came out or what the heck the result was. This was several years ago and a similar discussion was taking place right here on PA but the old sight. I think the idea has merit but I hadn't really developed enough testing skills at that time to really evaluate it properly. I think I would get some red oak or maple and plane it down and try it. I Know that tri lams tend to loose some of the perry benefits but still seem to perform very well. I think it is definitely worth a shot. If you do try it use the no set tiller method when tillering the bow out and it might help to evealuate how succesful the method is. Steve

[Badger]

  One more thought, I seldom do tri lam bows, I usually just laminate a back to a slightly too thick belly, when the belly is thick at glue up I notice that the bow continues to gain reflex as I tiller and then as I get closer to full draw will generaly settle back in about where I started. For some reason I tend to get confused when I start thinking more than 2 pieces of wood LOL. Steve

[Inuumarue]

Just a thought, to be perfectly honest I would rather my glue lines not be working at all.  The less stress you have acting on a glue line the lower its chances for failure (possible embrittlement over time).  Second NTD, If I remember my deforms classes correctly, by doing the glue up in two parts you move more of your forces to the inside of the bow, rather than mainly the outside surfaces.  It's sorta a force cancellation thing. The belly would be put into compression then pulled into tension, and with any luck you end up with a belly that is under equal and cancelling forces.  Your back would be under a greater tensional loading though.  However the bamboo would be my top pick for a backing to take that kind of abuse.  Just thinking it out in my head makes me want to guess you would take less set and avoid crushing a belly by this method, however if your core lam is not up to the task, you may crush it.   Take that with a grain of salt, just thinking aloud, I have yet to attempt it.

Adam

[NTD]

Thanks for your input Steve.  I'm definitely going to test this at some point.  It will probably be quite awhile until I have the time, materials and energy to put into "tests" though.  About gluing up thicker lams and gaining reflex as you tiller.  I saw that with my first 2 BBI's and then lost the gained reflex through poor tillering.  The rest of my laminate bows have been pretapered cores and I have still seen that happen early in tillering but not to the extent of those with thicker cores.

Adam,

I personally don't see any benefit to doing laminates unless I were to put stress on the glue line, i.e. Perry Reflex.  If I'm just looking to hold down splinters there's plenty of other backings I'd use. 

Your analysis is exactly what I was hoping for but wanted to see if anyone had some results not just theory.  Didn't want to waste these lams on an experiment. 

Thanks for the input everyone.

[Badger]

  I has always been said that by using 3 lams instead of 2 you are defeating the peurpose of the perry reflex. I think enough bows have been built both ways now to show that the 3 lam and 2 lam bows perform about equal if made right, even the multi lam bows seem to be keeping up. They are about 10 fps faster than self bows on the average. Well built laminated all wood bows are comming so close to what is considered possible right now their is not a whole lot of room for improvent. Steve

[NTD]

Steve can you explain how a trillam bow negates perry reflex?  Is it that the stress is moved to the midlam rather than the glue line?

[Badger]

  I was never one of the ones to really get into how the Perry reflex worked, i just knew it worked well to glue on a backing that would hold the bow into reflex as opposed to steaming or heating a bow into reflex. The accepted theory behind it may be questionable now or may not, possibly the tri lam bow is doing the same thing even though it was thought that it couldn't. I never have really totally accepted the theory but don't discount it either, sometimes just knowing something works is good enough. Obviously i would prefer to know why and how but you you know how that goes. Steve

[NTD]

Hmmm.  Thanks for the food for though.  Makes me wonder if there is any benefit to trilams at except being purty....

[Lombard]

Nate, sent you a PM with a link to a discussion that Dan Perry weighed in on, and it should help with some of your questions.