total thickness taper for glass bow design

[Jason Scott]

I need some help with lamination taper design. I want to build a bow similar to a great northern critter getter or bushbow. The only thing I am struggling with is how much total taper to use. These designs are mild r/d. I don't want to be whip tillered and I don't want most of the flex at the fades. So far I have built from a r/d form similar to Kennym's and have used .003 and .004. I have heard that a more mild r/d needs less, more like .002 but these tips are 9/16", which is sort of wide and I think they may need more than just .002 in order to flex enough. The target lenghth is 60" to 62". Any advice?

[bjansen]

Jason, I built several bows on a 68" mild R/D form (which I think is similar to a critter getter).  I will tell you my results of each build..maybe it will help.  Overall, I think .004 total taper is the way to go.

Here is a build along I did on one and you can see the form design and tiller I achieved with .006 per lam:

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=000558

That one was 68" long and it shoots great after a bunch of fine tuning on the tiller. A friend of mine made that form and his best shooters also had .005 to .006 total taper per side.  

I made another bow on the same form, used .004 total taper per lam, 66" shot better than the Paduak bow.  

I made a 3rd, carbon fiber back..69" .004 total taper per side...a little shocky on the hand...but I suspect if I go back and re-tiller it to even I could eliminate some of that shock.

I think .002 or .003 total taper per side would be way too little for my form. I think next glue up I am going to try .005 total taper per side with carbon on the back.  

good luck

[Jason Scott]

Thanks bjansen, I suspectected that but needed some assurance from someone else. I like your handles on that build along. That is the first bow I have seen with white glass and it looks very nice. Perfect for snow I guess.

Does anyone use power wedges in the tips. I am trying to imagine since I have never seen a bow with them. Does it matter how thick they are on the thick end?

[kennym]

I know a fella that uses .004 taper in 64-66" bows,but his are 1.25 wide. This allows you to use more taper.

I would think .005-.006 would be whippy at 1.5 wide at fades, "BUT" I don't build the long mild d/r bows.

Mine work great with .003 taper,could possibly work with .0035,but haven't tried that yet.

So many tests,so little time! Maybe when this pesky bow season is over!LOL

[Jason Scott]

Thanks Kenny, I was hoping to hear from you or Appex on this. I do plan on making it about 1.25. For some reason I really like narrow bows and I am glad you gave that info of more taper needed the narrower the bow. What do you know about tip wedges? Could that be why some bowyers use them? To keep it from being whip ended on a high taper rate limb? I appreciate your test. Very interested in the one for the effect of different core woods on the same bow design. I know a couple of people that watched that post but aren't registered with trad gang. You never know how many people you help out.

[strungstick]

I've made a number of, what I would call medium r/d bows, in the 58"-62" length with a 3 lam combination of .002 tapers each.  They are about 1 3/8" at the fades.  They are comfortable to shoot and not "whip ended" at all.

[Jason Scott]

stringstick, that sounds exactly like what I want to do. That sounds a lot like the critter getter special. Thin and short. So you are saying You used .006 total? Two glass and three wood lams for a five lam stack? What is an acceptable riser length, 16"?

[strungstick]

Jason- 2-glass and 3-.002 tapers.  The risers are 16" and are more in the 1 5/16" at the fades.
If you check my threads there was one a while ago that talks about concerns from some folks about too much taper.  When I was getting started a fairly prominant bowyer helped me out with this combination and I know that 1000's of bows with this taper combination are out there. All I know is they have worked well for me.  If you decide to go this route give me a pm and I'll give you a lam thickness recipe that should get you in the ball park for weight.

[Sixby]

I build a lot of 58 to 64 in d and r longbows. both mild and heavy d and r. I have used .oo2 very successfully in them all but I do a full length taper from the end of the fades to 1/2 in tips. I also belly trap which lightens considerably without removing a lot of poundage.

The tip wedge keeps the string angle good and helps eliminate stacking. I use a 24 in riser plus a power lam which effectively makes the fades three inches longer and more evenly distributes the curve towards the outer third of the limb.

What I am saying here is that the amount of tapers you use correlates to the profile of the limb and working area of the limb. Steve

[Jason Scott]

So I guess I understand that for a narrow bow, with less width taper from fadeout to tip, you need more stack taper. For a wider bow, because you can taper some width you will need less stack taper.

[kennym]

That has been my experience,Jason.

[sw]

im building a lot of R/D's and have been very successful with .002 and .003 in the tapers at 60 to 68 inches. The bows are a 1.5" wide at the widest point. I like to have a wide bow and taper the tips to 1/2". Just seems to work for me and allows me to keep the laminates thin. I do have a design with a heavy R/D thin bow that is made totally out of tapers - thin width your needing more taper as stated above.

Just got done cutting 24 .002 36" long tapers from maple and bamboo, now this has me thinking about using .004 to .006 for experimenting    


Dave

[Sixby]

Exactly Jason and what DAve said.

[Jason Scott]

Thank you guys very much. I have an idea how I will go forward with this design.

[Djoseph]

Mistake!