Discuss Riser design at the Recurve Bow within Archery Interchange Forums; Hi all, I知 looking for a bit of help. My son, as part of his ...
Hi all, I知 looking for a bit of help. My son, as part of his design and technology project for college, has decided to build a recurve archery riser. It will be a CNC machined riser, hopefully with IL fittings, but what he needs is a basic idea on what goes on behind the design of a riser, what criteria it needs to match, any FITA regs on riser design etc, so if anybody out there has a link/document on any useful information he and I would be very grateful. Thanks.
ps he is not planning on going into business, just wants to get a good mark :-)
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ADE, it sounds like a great project.
Perhaps I can help a little with some of the simpler stuff.Perhaps you know this already, but just in case.
Length= the standard sizes will, with different length limbs, produce bows of the usual range in total length. I would guess that a non standard riser might be difficult to sell.
Exit angle= the angle that the limbs lean back( away from straight up/down)
If unusual angles are used, the bow may be too lightly/heavily stressed when strung.
Overall shape, side view.= the shapes are straight, reflex, deflex.
straight speaks for itself.
Reflex has the limb pockets further from the string line than the grip.
Deflex has the pockets closer to the string line than the grip.
( there are more precise descriptions than that, but I think you can see the idea)
Overall shape ,front view= the sight window is the cut away that allows the arrow to be fitted to the rest so it could point straight ahead and still have clearance for fletchings.Window length needs to take into account the sight movements up/down when used with a range of limb stiffnesses. If the windown is too short, some higher powered bows will shoot arrows too high at shorter distances.( sight window is on the other side for left handed use.)
Grip position= some makers put the throat at the centre so the hand is half way along the length of the bow. Some put the arrow rest/button hole at the centre.I don't think anyone makes risers outside those two limits, but I'm not sure.
Grip= some are part of the metal of the riser; some have machining that allows different grips to be fitted easily, chance here for the archer to select their preference.
Threaded holes for attachments= nearly always one below the grip to fit a long rod.Some have hols facing the archer for back weights. Usually 5/16" unf. Similar for button and sight, threads vary for sights.
Balance needs consideration. Target archery risers will be balanced with the limbs and all the toys on. Risers with a good barebow lean will be better balanced without the toys, and probably have an option for putting in proprietory weights.
e.g. Hoyt v. Spigarelli
Overall appearance, being pleasing on the eye, may well affect sales.
In the Red
I have found a good stress package (software) is a must at the initial design stage - assuming a 3D application is being used, otherwise many trials (and errors) will be the result.
What might look like a workable design will fail at the first hurdle when put under load (unbalanced, uneven, twisting, warping etc).
My thoughts after many design trials are available in this forum if you wish, but I am sure your son will have his own ideas.
This may or may not help
Originally Posted by ADE
AMO standard can be dowloaded from here.
I think therefore I miss
Originally Posted by ADE
i'm sure for a small fee merlin may sell you a billet of ally.....
and maybe give you some info...
although you must remember it is their buisiness....
so don't be offended if they don't
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