Help me Design My Next Bow

[bowhunter15]

For anyone didn't follow my last build-a-long on here, it was a big success thanks to the help of people on this forum. It was a 68" R/D BBI. I may make another one to trade to a friend of mine for a nice shotgun.

For my next personal bow, I want to go short. I see designs of bows 54" to 58" that look intriguing, like the Big Jim Thunderchild, Super Shrew, Cari-bow Wolverine, etc. The reason is I want a bow that's easier to maneuver in my typical tree stand setups. I can make the 68" work, but often find the string hitting my thigh on close shots.

It appears that most of the bows I've listed are made of glass and wood laminates, with forward handles, a bit of deflex, and lots of reflex. Is it possible to make an all wood bow like a BBI or BBO with similar dimensions and 60-65# @ 28"? If not, would it be possible with a tri-lam? I'm guessing the amount of pre-glue bending that an osage or ipe belly can withstand is somewhat of a limiting factor. Can a short bow be made asymmetrical, or should the handle be centered to maximize the working length of the lower limb?

[Bowjunkie]

Yes to bbo... and yes to tri-lams. I've done it 56-58" long with bamboo and Osage, 60-70#@28", shorter bottom limb. Deflex/semi-recurves are especially nice for this application.

[bowhunter15]

Originally posted by Bowjunkie:
I've done it 56-58" long with bamboo and Osage, 60-70#@28", shorter bottom limb.

That may be what I try then. Any change you have a build along for that one? I see 3 Rivers has osage boards on sale right now, but they are 5/8" thick. I imagine they'd need to be tapered, which is something I don't yet have the best tooling for. Could get close with a bandsaw/beltsander and tiller from there I suppose.

[Roy from Pa]

Here is a 66" build, just make yours shorter..

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=012149#000000

[bowhunter15]

Are those parallel lams that you started with or tapered? Seems like when I look online, you can either find full length parallel lams up to 0.060" thick or tapered lams at 36" long, which obviously wouldn't be right for this type of bow.

[Roy from Pa]

My bows are all wood. The belly lam is parallel, core lam is tapered from 1/4" thick at the riser to 1/8th thick at the tips. I start out with 36" long everything. Depending on what length bow I want, I just cut some material off the riser end. These lams also need to be Z spliced together. So that will shorten the 36" up by 4 inches.

[LittleBen]

You can go pretty short, but you need to go wider if you're gonna try and keep the draw weight up. FWIW a really well made 40#er is deadly accurate and will kill deer just fine.

Here are two I built. Both forward handle, almost all mine are. The 40#er shot 140something FPS with a 500gr arrow at 25-26" draw. Not a rocket, but easily comparable to most 50# selfbows, certainly the dog-ish selfbows I have built lol.

Ipe is pretty good stuff, but in my opinion probably shouldn't be made narrower than osage.
Both these bows are pretty wide at 1.75" at the fades.


  http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=012112;p=1  

  http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=011930;p=1#000000

[halfseminole]

I have a 54" horn bow that's no wider than maybe an inch.  The design doesn't seem to need bent and spliced siyahs, just a core lam with thicker ends, horn and sinew.  Pulls about 50#@28", easily handles 32".  Might be worth looking at.  Weighs nothing as well...

[bowhunter15]

LittleBen, based on the pictures of your bows, it looks like you glued up the core and belly first, then added the tapered handle pieces, then glued up the backing strip over everything. Is that correct? Looks really nice.

[mikkekeswick]

Rule of thumb for wooden bow length is drawlength x2 = 4inch handle and 2 inch fades = 64 inch.
Making a bow a tri lam instead of two lams won't help in getting more draw length.
Halfseminole has a point about making a hornbow but have you got a couple of years to get a handle on making them!?! You could make a Turkish bow at 42 inch for a 28 inch draw.  

[LittleBen]

Originally posted by bowhunter15:
LittleBen, based on the pictures of your bows, it looks like you glued up the core and belly first, then added the tapered handle pieces, then glued up the backing strip over everything. Is that correct? Looks really nice.

This is how I term the parts from back to belly side:
Backing, riser, core lam, belly lam and handle block. Everything except the handle block gets glued up together, then the handle block is glued on once the bow comes off the form. But you could do it in multiple steps if that makes it more manageable.
Also, all the lams were tapered to .002" before glue up. This doesn't give you a lot of room to belly tiller though so I'm hesitant to recommend this approach. The stack thicknesses im using are very specific to limb length, amount of reflex, and side profile (r/d).

@Mikekeswick, maximum draw on these bows is approximately 110% to 120% of limb length. So 58" bow - 12" riser = 46"/2= 23" limbs for up to 26" draw. The lighter bow is closer to 60" but with a 14.5" riser. I haven't torture tested wither so they might survive more draw but who knows.
They are relatively wide (1.75") thin (<.5") limbs, and have the side profile to reduce stack.
 I wouldn't be so bold on a straight limbed bow, and I would warn the OP that although it can be done, these were not 28" draw bows and they weren't my 2nd or 3rd or 20th bows.
Give it a shot, but stick with it if the first try doesn't turn out. At the same time, your first was great work so I have faith you can pull it off.

[fujimo]

you got some pics of that bow ED

[halfseminole]

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=011195;p=150

Last pic on the page.  Need to spin it a new string.

[Bowjunkie]

Hmmm, guess I'm making bows I shouldn't be makin     Best part is, they're the best I've made.

Yes, I did a build-along on another forum. I'll see what I can dig up when I get home.

[mikkekeswick]

Rule of thumb for a straight limbed bow! Nothing in this game is set in stone    I've made plenty shorter too but you just get closer to the limits - I guess it also comes down to what your precise requirements are too. Adding deflex out of the riser will certainly allow for a longer draw. Wider, thinner limbs can bend further. Highly elastic belly woods will allow more bend without excess set. The list goes on and on....but a general rule of thumb is still a useful thing.
The easy way to make a short wooden bow is make it bend (a shade)in the handle and sinew back it.

[LittleBen]

Maybe that's the easiest answer ... A bendy handle bow would make that draw and length no problem.

[Bowjunkie]

Mike, I didn't think we were in a discussion relegated to straight standing bows. That would surely change things.

[LittleBen]

Jeff, quit yapping and start posting some of your RD bows! Lol This guy wants to see what's basically the ambush bow!

[Bowjunkie]

Here's a profile that will allow you to do what you're asking. This is a tri-lam. Bamboo back, yew core, and osage belly. 58", 57# @ 28", asymmetrical. It's 1 1/4" wide. I've done the same thing with various profiles, hybrids, full recurves... and some very similar with two piece layups. i.e. boo-backed osage.

I kept this one relatively short in the handle area to maximize working limb length, while maintaining the stiff handle section. It has a 4" handle, 1.5" flares, and 1.5" fades for a total of 10"... and it's actually a little less than that after the dips were finessed.

I have a full build along of this bow, but posting pictures on this site is a pain   :(

[Wolftrail]

Nice profile on that bow Junk.