Hill Style Build Question/Advice concerning Limb Taper

[Cory Hayes]

I'm planning to build a Hill Style bow: 68" long, 1.125" wide at fades, 50-55#@28".  This will be my third ASL build.  These are my on-hand materials and proposed stack (back to belly):

clear glass (.040)
osage veneer (.030)
boo (.120/.002 taper)
boo (.120/.002 taper)
boo (.110/.001 taper)
osage venner (.030)
shedua riser (14"-15")  *still undecided on length*
clear glass (.050)

Total stack .500/total taper .005

Question: Will a tip overlay do the same work as a tip wedge in keeping the limb tips stiff?  I'm concerned about the taper (I've never done .005 before) causing the tips to bend too much and rob the bow of cast.  Is this even a legitimate concern?

I've done overlays before, but I have never attempted a wedge and wouldn't know where to start.

My previous builds had a wider limb (1.25 at fades) and a thinner stack.  I want a deeper, narrower limb, so I've gone with more taper.

Also, any advice or comment on my proposed stack is welcome.

Thanks,
Cory

[Flem]

Sounds like a fun build, go for it. I can only speak to a couple of your questions. I don't use overlays or wedges. Lots of people use .006 taper with good results. If your worried about it being whippy, maybe creep up on your target width, don't narrow it all the way down in the beginning. I would use a shorter riser, 13"-14", gives you more working limb to tiller with. You have six(6) glue lines in your stack, thats a lot of epoxy. I like four max, three preferably. I can't prove it, but I work off the premise that epoxy is dead weight in a bow.

[jsweka]

Based on my results, I'd suggest you increase your stack thickness to about 0.515 and use 0.050 glass to hit 50-55# (assuming your form is straight with no reflex).

I like the 0.005 total taper rate in straight bows and I've never put in tip wedges.  I do put on tip overlays for aesthetics and use fiberglass in the overlays to make the bow fast flight compatible.

Good luck with the build.

 

[monterey]

That same stack with the same dimensions EXCEPT, 69" NTN, 15" riser, 7/16" wide at the nocks, tip wedges 4.5" bear paw glass and about 1" of reflex came in around 44#.

[bjansen]

I really like the look of a slim tip wedge, but even when I use them I put a minimal overlay on top in order to maximize the teardrop shape you want the string to sit in without taking too much of the glass away. Measure where you want your tip wedge fade to end on each side of the limb, and use a sharpy marker to mark that spot on the side of the lam stack.  Keep the wedges long so you can push them in after you get the stack glued up and on your form (i.e., you do not want to lose them in your stack or have them in the wrong spot). 

[canopyboy]

I think you have a good plan, and generally agree with the other comments so far.

Tip overlays aren't big enough to really stiffen the tips IMO. I like to put in short (maybe 4"?) wedges, but they really aren't long enough to change the limb profile at full draw much compared to the ones I've made without. I like the look and it makes me feel a little more confident when I make the tips really fine and still use modern string materials without the overlays. (I often skip overlays or make them very minimal in order to keep tip weight down.)

As for stack, I would go significantly thicker based on my database of Hill bows I've measured and ones I've built. Most of my personal datapoints are for 66" bows with 14" risers and 1-1/8 at the fades, but my spreadsheet does adjust for longer (or shorter) working limbs, etc. At 68" and 14" riser, I would probably go with .050 glass on both front and back and closer to 0.580 total stack and 0.006 taper. That will likely land you closer to 55# on a straight form with a square limb cross section and that many glue lines. If you round the corners and trap the back very substantially (I like to do both to bring it down into my target weight) you should easily be able to hit your sweet spot.

Now, I think at your draw you would be perfectly happy with a 66" draw if you keep your riser at 14" or less. So you can always try to play it a bit safe and just plan on piking the bow if it starts to come in too light. My calcs for a 66" version would be 0.560.

[Cory Hayes]

Thanks for the replies and the advice!  I would have never gotten into bow building without the advice provided by guys like ya'll.  Everything ya'll are telling me gives the impression that I'll probably come in too light, i.e., around 45#.  I'd be okay with 50#, to be honest, but one of the goals of this build is to get the narrow limb, i.e., 1.125" at the fades.  From what ya'll are saying, it doesn't look like I could even get 50# with the length and width I'm shooting for.  So...

...I'll be trying to get away with ordering only one lam to supplement what I have.  So, I'll probably order another osage parallel at either .060/.070 (keeping the .005 taper) or .100/.110 with .001 taper (increasing the total taper to .006)--I'm still undecided at this point.  The new parallel will replace the belly veneer.   By the way, the parallels aren't really osage, but osage-colored yellow birch from Bingham Projects. 

I haven't been happy with my first two attempts at Hill Style bows--even though I hunt with the second ASL I made--and I'm hoping the third will be the one where I get it right.  Two more questions if ya'll are willing:

1.  Is the .050 back glass crucial?  I've read that Northern Mist ASL's have .040 glass on the back.  Also, Dick Wightman has an ASL build with .040 glass on the back (both with .050 on the belly).

2. How far past the fades do ya'll start tapering the sides of the limbs?  This is one of the things (I think!) I've screwed up on my first two bows.     

3. I'm hearing that wedges go into the limb 4" or so.  Is this correct?  Is there a typical butt thickness and taper rate for wedges (for an ASL)?  Could I use the tapered end of an bamboo lamination for wedge material, or does the wedge have to be fiberglass?   I've never tapered fiberglass before. 

I sometimes use D97/FF  strings, but I want to keep the tips as light as possible, so the idea of a good wedge versus an overlay (I usually use antler or whatever the riser happens to be made of) appeals to me.


Thanks,
Cory     

[canopyboy]

1 - Absolutely not. 0.040 glass, especially on the tension side is fine. As you go to thinner glass, I feel you get a little more of a softer 'wood' feel in the action of the bow. I do that on purpose sometimes. For the same stack thickness, it will give you a lightly light poundage though. I wouldn't worry too much about it if you already have the glass. Even the change in stack to compensate is fairly minor.

2 - I start taper in the layout at about 8" from what I mark as bow center (and I make my top limb slightly longer). But by the time I'm done sanding I'm sure the taper really starts about the end of the riser fade. It's such a shallow angle it's hard to tell.

3 - For me, yes 4". I use the 0.030 core tuff. I taper by hand on the edge or belt sander just so it feathers in nicely. I start with material about 6" long or so so that they end up in the right spot when I cut the limbs to length out of the blank. It's not a precision taper. If you want to stiffen the tips, bamboo reverse tapers should work but they still need to feather to zero. I use glass or core tuff to help me feel better about using modern strings with no overlays...I've never had one break that I know of.

So if I understand, you already ordered all your lams? If it were me, I'd replace one of your bamboo lams with a thick one to make up the difference and leave your belly lam as originally planned. Put it right in the center of the bow. But just personal preference really.

[canopyboy]

This is my main bow for almost 5 years now. I was recently figuring it out, and we're in the 10s of 1000's of shots on this, multiple D-97 strings (flemish and endless), a lot of abuse (rocks, sticking in the dirt, shutting in car doors, flying across the gravel, braking my fall down cardiac ridge at ETAR, etc). Tips still holding up with no overlays.

[jsweka]

I also accidentally dry fired that bow of Canopyboy's.  The nock on my arrow was too big for his string.  Ooops.  I still feel bad about that one. 

Anyway, that bow is bomb proof!  (And Sweka proof)

[Cory Hayes]

Thanks again for the replies.  I went with the .070 "faux" osage parallel (it is a few dollars cheaper than a new, extra thicker boo taper) to keep the .005 taper rate and save a little money--one of the reasons I make my ASL's is because I could never justify the expense of buying a new one.  I can hear my family now:  "So Dad can spend $700 on a bow, but we can't..."  Anyway, the total stack will be .540/.005 taper.     

I also ordered a brown piece of core tuff for the wedges.  I'll post pics in this thread when I'm done with the bow...hopefully sooner than later.  I hope that my bow too will be both bomb and Sweka proof! 

One last question:  Does it matter where I insert the wedge in the lam stack? 

Thanks and good hunting/shooting to all of ya'll!
Cory 

[monterey]

I don't think it matters, but I keep mine toward the middle of the stack just for appearances.

HH Archery has the glass tapered tip inserts at $3.  Probably each.