static recurve ...... bowyer question

[Rick Perry]

I am thinking about laying up a new bow with static recurve tips similar to  a soveirgn ballistic ......... how do I keep the tips from bending ? Will a reverse taper in the tip do it ?? how thick does it need to be ?

 Should I use tapered or parallel lams in the limb ??

 any ideas ????        

[Rick Perry]

ttt

[Plywood Bender-laptop]

My Ballistiks look like they have tapered lams (thicker at the riser).

I don't see any reinforcement at the bends.  I think the dramatic bend strengthens that portion of the limb and makes it static.

Disclaimer: I never actually measured any of this.

FWIW-

Carl

[Jason Jelinek]

My guess is that even on the Ballistic the recurves bend, but since they are so dramatic it doesn't look like other recurves when they pull out at full draw.

Jason

[onemississipp]

I have never built a lam bow, but on a static recurve selfbow the recurves are thicker to stop them from bending. I would think a reverse taper in the tip would be the way to go.

I really don't have a clue about lams....

[Shawn Leonard]

RER bows have static tips on their recurves, I own one and have talked to Kevin a bunch of times. go to their web-site and give him a call. I am sure he wouldanswer any of your questions! Shawn

[Rick Perry]

thanks ........ good responses  .......... anyone else ?????

[Mark Baker]

A static recurve tip is just that...static, it don't bend.  To achieve that it must be thicker at the angle portion of the recurve.    The sheepeater spirit uses extra glass at that point.   Selfbows are built thicker, and other bows build up the area with wood (grumley style or similar).   The statics act as levers, and there is an optimum bow length, draw length corespondence for them to work "right".   Statics are just dead weight on a longer bow....but really work magic at shorter lengths.  Good luck!

[cjones]

Mark, does the length of the static tip correspond to the bow length? Say on a 60" bow the static tip would need to be short than it would on say a 56" bow?

[Glenn Newell]

I've made static recurves and I have had the best results with parralel laminations...Glenn...

[Rick Perry]

Glenn

 It seems to me that parralel lams would be best for a longer draw length . I pull a full 31" ......... whatchya think ????

[Jhoneil]

Tip on my Don Brown static recurve

   
   

[Mark Baker]

Brent Rudolph really is the guy that knows his statics.   What I can say from learning from him, and just common sense, is that the length of the static should be long enough to provide good leverage but not so long as to be unstable.   Also, and perhaps more critical is the angle of the static.  To work right the statics should "open" or come just past vertical just before full draw.   At this point they are compressing the limbs getting their most from them and at the same time relieving string pinch at full draw.  The draw force at this point actually shows a "letoff" effect, both in decrease of the increase (it still increases but less so) and in finger pinch, making  the bow seem extra smooth.   With a longer bow, it is much harder to achieve this...

Also at this point, the bow is about to "hit the wall"  of stack....so design for a particular draw length is important to get a static to work "right".

Hope this makes sense....like I said, I am a recent student of all this too.

[cjones]

Makes sense to me Mark. Thanks for explaining.

[Glenn Newell]

Perry, I only have a 26" draw and the first static I made had parallel laminations but she only come out at 37#@28". I shot 600 grain arrows out of this bow at a 28" draw through my mates chrony and it was sending them at 166fps which I thought was very good for that poundage and those weight arrows. The next one I made came out at 65# with parallel lams again and she really sends them down range but I haven't had a chance to shoot them through the chrony yet. Going out western Queensland to hunt pigs and goats next week  so we will give these bow the real test when we get out there...Glenn...

[Mark Baker]

Whether or not you use parralels or tapers in your limbs, really is a reflection of you limb design also.  To achieve best tiller in any bow, you will have some reduction of limb mass as you reach the tips....either in width, or thickness.  So how you design the bow, and the length of the working part of the limb, should be you decider in this respect.  

Here is a pic of a recent static-tipped, sinew backed osage bow I just completed.   To be honest, I got there by shear luck....but it works as it should, smooth drawing with the sensation of lettoff in the last couple inches of draw.  I reinforced the angle in grumley style.  This bow is very fast and very quiet.   It is 57 inches, nock to nock, and mid-sixties in poundage.  

 

 

[Rick Perry]

very cool !!!!!

[Rick Perry]

ttt

[Glenn Newell]

Tapered and parralel lamination have a big effect on the speed of a bow and how a bow draws.
You often see longbows with a lot of timber laminations in the limb core and all of them are tapered. I normally find these bows to be whip ended and not all that flash in the speed department and stack as you come to full draw, when the bowyer could have just used less tapers or less agressive tapers and they would have had a much more pleasing bow to shoot. Bows built with all tapered laminations never seem to bend much if at all down near the handle fade-outs where the bow needs to bend to store energy.
Different with all wood bows as you can control tiller a lot better through the tillering process but with building a fibreglass composite bow you are trying to predetermine tiller to a large degree before the bow is glued-up. You can adjust the tiller on a fibreglass bow but don't have the flexibility you have with all wood bows.

[Rick Perry]

more good info !!!!!  ............ Thanks all !!!