Perry Reflex

[DC]

With Perry Reflex there is something going on because of the tension/strain between the two pieces of wood. It stands to reason that the more tension the better. I remember reading that the thicker/stiffer the belly the better the final result. Does it also stand to reason that if you deflex the belly with steam or heat you will get better results from the Perry reflex?

[bradsmith2010]

im over simplifying,, it would enable a bow to hold more reflex ,,,not sure about the deflex in belly,,
seems if both pieces were reflexed ,, it would hold more reflex,, I am just guessing,,

[Stick Bender]

Are you saying deflex the whole core then glue up into reflex or just heat deflexing the deflexed part of the D/R ?

[DC]

Deflex the whole core and then glue into reflex.

[Stick Bender]

Ok that's what I thought my guess is it would be counter productive , isn't Perry reflex just reflex held in by a glue line ?  Of course there is only one way to find out  But the interesting thought would be to heat bend your core to your D/R profile I would bet you would hold the profile more then not doing it , in multi lam core that happens naturally to take the shape just my thoughts for what it's worth !

[SLIMBOB]

I believe yes, as you are not compressing the belly until it reaches what would have been the relaxed position.  That is my understanding.  Some of the lam bow guys I know poo poo the whole thing...or much of it I should say.  Seems to me to to be a reasonable conclusion.

I would be very curious what the results would be thru the chrono, one way vs the other to compare.

[DC]

I've already done one limb so it's gonna happen. I don't know that there will be a big enough difference to notice. I think there is more to Perry Reflex than just holding in reflex better although it definitely does that. I think there is some witchcraft involved If you reflex both pieces and glue them together with no Perry they will just stay like that. The neat thing about Perry is that when you start tillering the bow will gain reflex. I think the reason for that is that when you release it from the glue up the two pieces are fighting each other and as you tiller you are weakening the belly so the back starts to win the equilibrium war so you get more reflex. I've had a bow gain an inch and a half in the first 10-15" of tillering. They seem to lose it all by the end of tillering. In my case because I'm tearing apart a "finished" bow and gluing it back together I won't be doing much tillering(touch wood). I'm totally willing to be convinced T'm wrong here as I don't have a good understanding of what Perry does. It does seem to work though, as my best bows are Perried. Could be coincidence though. To my way of thinking the idea is to create as much "tension" as possible between the two as possible and  the way to do that would be to reflex the back and deflex the belly.
I guess I'm kind of thinking that if the belly's "normal" position is bent that it won't actually come under compression until it gets back to that postion. By then you're at half draw. Dunno, just a thought.

[Stick Bender]

Well at least your making the bow you can take me out of my arm chair speculation mode 

[DC]

I was treating the other limb and had time to think. Dangerous If "if the belly's "normal" position is bent that it won't actually come under compression until it gets back to that postion" is true then it should be better if the back is deflexed before the glue up too then the back wouldn't be under tension til half draw. This is seeming silly. Anyway I've always thought that Perry Reflex must be temporary. Think about it. If there are internal stresses set up in the bow eventually the wood will readjust to accommodate them. If you leave a bow strung for a year it will have a serious bend to it. I think the same will happen to a Perry bow. After a length of time it will "set" into the new shape. As I was writing that I realised that I've split a bone dry stave and had one side bend one way and one bend the other so i guess some stresses will stay. Still puzzled.

[SLIMBOB]

I have made 2 with perry reflex. Both broke on me and both at 27 inches. My fault on one and no idea on the other. Both were nearly done. Tension failure on both. So I have played with it some. I. Want to do another at some point.

[SLIMBOB]

I think the stress is in the glue line. The problem I see is taking wood off the belly to tiller. That screws it up. The tiller needs to be close before glue up I think.

[Stick Bender]

I think slim is right on the glue line I have herd guys say that multi lam bows hold the reflex better but then you have the extra mass of the glue , but I would think a multi thinner lam core would handle stresses better but the bottom line is how it equates to performance , I think slim is also right on being close to proper tapper at glue up makes a difference the last bamboo bow I made I pre tapered the core & probably took 10 minutes to tiller keeped a fair amount of reflex but I think the closer you are to proper taper at tiller the more reflex your keeping with self bows to !

[DC]

I The problem I see is taking wood off the belly to tiller. That screws it up.

Why would taking wood off the belly screw it up?

[Marc St Louis]

I have found that reflexing the core before glue-up is much better.

[SLIMBOB]

I have a lot of interest in this subject, and to date no successes, so keep that in mind as I ramble through this, but giving the bow PR causes more stress internally so less stress on the surfaces. You want the back pulling against the belly at a stalemate. As you remove wood from the belly, and reflex increases, you lose the internal conflict because you weaken the belly. Now the PR advantage is lost and you end up with just a reflexes bow. I believe you want a thick belly lam and a thin back with both being well tillered before glue up. Side tiller to touch it up.