Primitive Archer
Main Discussion Area => Bows => Topic started by: sailordad on October 01, 2008, 06:59:42 pm
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now i think i understand what deflex is(when the limb bends toward the belly,reflex would be when the limb bends toward the back of the bow.
please correct me if i am wrong.
now what would perry reflex be?
i have heard it mentioned several times and dont really understand what it is. :-[
thanks
tim
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Tim you are right on both counts. The Perry reflex is pretty simple.When I do it I put a 4x4 block under each tip. then after everything is glued together I clamp the center of the bow down snug to the table. When the glue dries, it will hold in a reflex.
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so then my boo/hick bow that i am working and posted pics of is actually a perry reflex/deflex
because of it being a laminated bow with glued in reflex?
???
tim
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No, I would call that one a R/D glue-up. A Perry reflex is what it says,"reflex", It's glued up and clamped to look like a smile :)
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so then it would reflex at the handle area out to the tips?
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so then it would reflex at the handle area out to the tips?
Here is one way to get Perry Reflex....but most of the times you just put the 4x4 blocks out by the Tips and clamp the Handle down
[attachment deleted by admin]
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to milk the most out of a perry reflex, you need to tiller the bow down to 12-15", maybe even 20". then glue the boo or hickory slat onto the back while inducing about 4-5" of reflex.
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Me too.
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Some time ago I had an interesting email conversation with Dan Perry. For me amazing to chat with an archery hero and he was so kind and helpful.
As I understand it and as Dan so elegantly described it, Perry Reflex is simply glued in reflex. It is simple, but like many simple things we all think we could have discovered, it takes a wise man to discover it for us! If the backing and belly are glued together, if the belly is one piece rather than many then tension and compression are induced and held at the glue line. The stresses induced by the glue up are opposite to those at full draw. You need to draw the bow a few inches and pounds to get the working surfaces back to zero stress and this draw length and weight is "free" extra energy.
Dan told me (and my experience bears it out) that a belly slat wel tillered will have aprox 10lbs at full draw added by adding the backing and 10lbs added for each inch of reflex. In this way a bow that has the mass of a 50 lb bow could easily shoot like an 80lb bow with a backing and 2 inches of glued in reflex.
Oddly, the Perry Reflex reduces the stress on the bow rather than increasing it. Perry reflex can recuce limb tip mass rather than increase it as with some other methods. All in all it is a big boost to bow performance if you understand how it works and how to get the best out of it.
Pre shaping and tillering the belly and backing is important. The ideal is to glue it up and then remove nothing. Every bit of belly or backing removed is tensioned wood lost, is Perry effect lost.
A little Perry Reflex goes a long way and weird things happen if you don't heed this advice. Put in too much relfex and you will have a monster reflexed unstable bow. As you remove wood from the belly to reduce power and reflex the reflex actually increases! I had a hickory/ipe ELB bow with 7 inches of Perry reflex that pulled 120lb at 3 inches, that refused to loose weight, that stretched a non-stretch string, flip flopped and broke.
Perry Reflex works, treat it with respect and you will get some lovely slim high power bows.
Mark in England
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sounds like I did it right , Mark. The hickory/ osage I'm working on now is the first time I tried a Perry reflex. Thanks Mark.
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What Mark Said... :)
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so then if one is going to make a bow in the PERRY REFLEX style
you should have the belly lam already tillered to what you want,minus 10 lbs for he backing and minus 10 lbs for every inch of relex
that is going to be glued into it. do you have to do any thing to the back lam prior to glue up other than making sure it is perfectly flat and the same
shape of he belly ? ???
how much does this normally change the tiller once the two are glued up?
tim
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The truth is there is no such thing as " Perry reflex" in bow making. Somehow this term got started when Dan Perry was making flight bows and gluing in added reflex to enhance performance, and boy did this term stick. I have been doing the same for years and properly called it " adding reflex" be it either with a heat gun or while in the process of gluing on a backing.
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a perry reflex is different than just "adding reflex" though. i always understood it as the effect of this particular kind of reflex, not as the practice per se. the bow is itself not reflexed, not in the traditional sense. basically, a reflexed backing is added so the thickness of the limb is divided between the belly half, which is largely normal, and the back half, which is independently pulling the belly forwards. the belly, not really being reflexed itself, is pulled on by the backing towards a reflexed position. the thing that differentiates this style is that a lot of the stress is held within the glue line. when the stress is focused on the back of a bow you may pull a splinter. when the force is focused on the belly you may get chrysals, crush the belly, hinge, break outright, etc. with the stress focused on a spot in the middle of the limb the chances of breakage due to that added reflex strain is greatly diminished.
sailordad, i wouldnt worry about the "extra pound per" stuff, that is a generalization. while it may be true, that isnt the most useful or effective tool to use as a way to begin the building process. just floor tiller the bow, then reverse string it even a tiny bit. when the backing is glued on in a reflexed fashion you should have a perry reflex. the perry reflex is a good way to use engineering principles to get a substantial amount more work out of a set up than would be otherwise possible. similar advantages can be had heat treating the bow, sinew backing it, just drying it in reflex, adding recurves...it is another of those trade off things. on a longer bow, the lightness of a thin wood backing may be more helpful than the reflex drawing potential of a (heavy) sinew backing, for instance. if you want to invest the time to add a backing and use this style, it can lead to efficient designs. SOM
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Say What? I have made a pile of bows and gluing in reflex is gluing in reflex, no great mystery. My backing do put a lot stress in the glue line, that's adding extra reflex with a backing. Using a heat gun is another issue and a bow much less likely to retain this added reflex.
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to milk the most out of a perry reflex, you need to tiller the bow down to 12-15", maybe even 20". then glue the boo or hickory slat onto the back while inducing about 4-5" of reflex.
This is a good thread. But mostly, I am glad to hear from mechslasher :)
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Eric, you are absolutely correct, glued in reflex has been around for years. I think Dan Perry took the time to explain it's advnatages and the process got his name tagged on it. I was glueing the shapes into my bows before I had any clue what I was actually doing, I just knew it was easier to glue two pieces of wood together to get a certain shape.