Author Topic: The "So You Wanna Build a Bow?" Build-Along (Read 20005 times)

Doug Treat · « **Reply #120 on:** December 13, 2009, 07:44:00 PM »

4est, I have been following this thread too and think I might have another go at making a bow (my wife calls it my "wood breaking" hobby as I've tried before and failed). It seems this pyramid design might just be a better one for me to try. Sounds like it is more forgiving and easier to tiller which gave me fits when I tried before. One question I have (or maybe a few :^). I want to try to increase the length, decrease the width a bit, increase the thickness, and increase the riser length so I can see better (it looks like your design would have the widest part in my vision with the way I shoot-with just a little cant). I draw 29". Here's my plan right now: 74" total length, 12" from center to widest part of the limb which I want to make 2 3/4" instead of 3", My riser would be 20" and would stop just short of the widest part. My limb thickness would be 1/2" to start with. I would leave the limbs straight (no recurve). I'm shooting for about 50# @ 29. Do you (or does anyone else) see any problems that jump out at you with this design? Would all these changes change the easy tiller design too much and make it a non-pyramid type of bow? Thanks.

4est trekker · « **Reply #121 on:** December 13, 2009, 09:47:00 PM »

Doug: I'm glad you're going to give bowmaking another go-round! And remember that breaking bows is part of the game. If wood was meant to bend in a circle it would grow that way

Now, let me see if I get your description right:

Total bow length: 74" ntn
Total riser length: 20-22" (???)
Limb width at widest: 2 3/4"
Limb thickness: 1/2"

I would be hesitant to make your riser that long. I wouldn't go over 12" max (even that would be really long for my taste.) With your dimensions you render the working part of each limb only 27" long. The bow in the build-along (which is 6" shorter than your proposed bow) has a working limb length of 30" (3" inches longer!). Combine your plan to narrow the limbs, and you have actually taken a step in the other direction. Here's what I would suggest:

70" ntn
10" riser length (that'll give you an inch more on each side than the bow in the build-along)
2 3/4" limb width at fades
1/2" limb thickness (may need to adjust this)

Others may have more insight and better suggestions. But I hope this is a good starting point. I'm excited to see what you get out of your efforts! Post lots of pictures and questions and you'll get a bow out of it!

Doug Treat · « **Reply #122 on:** December 13, 2009, 09:59:00 PM »

Thanks, Yeah, my whole idea was to get that wide part of the limb out of my line of sight, but maybe your suggestion with the narrower limb width and that little extra riser length will be enough. I'll let you know.

SSGN_Doc · « **Reply #123 on:** December 13, 2009, 10:08:00 PM »

If you aim with both eyes open your non dominant eye should be taking in the target, while your dominant eye is looking more or less the line the arrow will take to the target. Kind of like the Benden aiming concept used for shooting red dot sights on rifles, you brain super imposes the images a bit. The sight window becomes less relevant in this more instinctive shooting. These bows point pretty naturally where you are looking. I point at my target, more or less, with my left hand and let go when I'm pointed at the target.

Doug Treat · « **Reply #124 on:** December 14, 2009, 04:19:00 PM »

I've found that my dominant eye (right) needs to have a clear view of the target or my non-dominant eye will take over and wants to line up the tip of the arrow. Then my shots will go far to the left. But now we're getting off topic...back to the pyramid bow. I have a couple more questions for 4est. Picking out the wood: I've been told that the edge grain is most important when picking out material for a board bow (looking for run-outs, etc.), but it sounds like you are saying to just look at the face (the 3 1/2" side) of the board that will be your back of the bow. Did I understand that right? Next question: I don't have a band saw but I do have a 12" table power planer. I thought it might be easier for me to plane down the thickness of my board before gluing on the riser since the thickness needn't change. I guess this would make it more difficult to get the riser taper just right without cutting into the limb, huh? Question 3: What is the reason you like to add the recurve tips? Does it increase performace significantly over a straight limb bow? I like the looks of the recurve limbs, but was wondering if it's worth the extra time to make. Thanks for your time and for doing all the work for this build-a-long.

Doug Treat · « **Reply #125 on:** December 14, 2009, 04:36:00 PM »

OK, I looked back and it looked like Razorback had a similar question about doing the thickness first before glue up. I'm not sure I understand why the glue joint would be more inclined to fail this way, but I'm sure I'm not thinking of something.

bubby · « **Reply #126 on:** December 14, 2009, 06:00:00 PM »

Doug, you should be able to narrow the bow and stay about 68" ntn if you get a good hickory board

4est trekker · « **Reply #127 on:** December 14, 2009, 06:45:00 PM »

Doug:

Question 1: Yes, I focus mainly on the side of the board that will be the bow's future back. It's a technique described by Mark Baker and one that produces bow after bow for me. The grain on the back won't change when making the bow. Looking for perfect grain on the edge of the bow is fun and all, but will nearly ALWAYS change when you make the bow because you're shaping the profile of the limb (i.e. narrowing it). Again, Mark Baker describes this in detail and with much more clarity than I can here. I will try to post a direct quote from him in the next few days if I have time. You might need to remind me.

Question 2: When you use 1" dimensional lumber (actually 3/4" thick) and glue on a riser of identical thickness, the joint between those two pieces of wood falls midway up the radius of the fade. Therefore, it's not receiving as much stress because it's thicker there and isn't bending as much. However, if you were to plan the stave the thickness first and then glue on the riser board, your fade would start precisely at the glue joint, and would receive tremendously more force. That is, you've got the most amount of pressure (since the inner third of the bow limb does the most work) concentrated on the thinnest edge. This feathered edge of the riser board will break away and fail under the force. Another way to say it is, the further you go up the fade out radius, the less force is being exerted on the wood. So, the higher your joint between the riser block and bow blank is, the less stress it has to endure.

Question 3: The recurved tips add a slight increase in performance by placing the tips closer to the zero line between deflex and reflex. The further the tips are to being even or even reflexed beyond this line, the more energy you store during the draw. Let's take two identical bows. Both are osage flatbows with the exact same dimension and pull 50#@28". However, bow A has 2" of string follow while bow B has 1" of reflex at the tips. Although they pull they same weight, bow B will have more cast because it's storing more energy. That is, the limb is doing work sooner in bow B than in bow A.

Hope these answers help. I'm not the best at explaining things. Let me know what I need to clear up!

P.S. Estes Park, CO is one of the most beautiful places on the planet. Some of my fondest memories from my childhood and now with my own family are from that area. You sure are lucky!

cooter · « **Reply #128 on:** December 14, 2009, 07:02:00 PM »

Total bow length: 74" ntn
Total riser length: 20-22" (???)
Limb width at widest: 2 3/4"
Limb thickness: 1/2"

Holy hanna, what kinda bow you making.

Just came back from too long a vacation from here. 74"ntn. imho way to much wood to get that arrow moving with any speed. Remember you need to transfer the stored energy from the limbs to the arrow. With that much wood a lot of the stored energy is going into getting those limbs moving and wont be transferred to the arrow. I've made bows with both limbs shorter than your riser. 2 3/4" wide??? cut that in about half depending on the wood your using.

My first question what type of wood you using?
Second question what draw weight you shooting for?

Just some food for thought,
Cooter

Doug Treat · « **Reply #129 on:** December 15, 2009, 10:08:00 AM »

Cooter, 4est has me rethinking my layout now. I think I will do what he suggested: 70" NTN, 10"riser, ect. I hadn't really thought about how much less working limb I would have with my long riser idea. 4est, Thanks for all the info. That clears things up in my mind a lot. Yep, Estes is a pretty nice place to hang one's hat.

SSGN_Doc · « **Reply #130 on:** December 15, 2009, 05:22:00 PM »

Here's my daughters bow, now that it's finished.

David Holt · « **Reply #131 on:** December 15, 2009, 11:39:00 PM »

Nice bow Mark....sure it's not yours?

OK...workin on bow #2. This one is 65" NKN, 2.5" at the fades to 1/2" tips. It pulls about 46# @ 27" right now. The problem I'm having is that it is taking alot of set/string follow. Unbraced overnight it has about 2" on one limb andn 3" on the other. When I brace it and shoot it a few times the string follow shoots up to over 3". I poured through the TBBs and I think I may have braced it too high initially and it doesn't help that it's like 100% humidity all the time here in SE Georgia (84 degrees today). I went and bought a heat gun and put a little reflex in the limbs and heat tempered the belly. first time doing that so I probably didn't do a good job

. I then left it on the front porch overnight to soak up some moisture (might as well have been gren again the next day). The heat tempering did't help a bit. I have put it back into MORE reflex and heat tempered the belly for longer this time and left it in my garage.

David Holt · « **Reply #132 on:** December 16, 2009, 01:18:00 PM »

Guess I need to learn how to make my pics smaller!

dbscott · « **Reply #133 on:** December 19, 2009, 11:06:00 AM »

Here is another amateur question. How do you know when you need to back a bow and does it add draw weight to the bow? I am still working on my but haven't gotten a chance to do much with work and Christmas coming right around the corner.

David Holt · « **Reply #134 on:** December 19, 2009, 11:31:00 AM »

dbscott,

1st a plug, buy the Traditional Bowyer's Bibles. they are a wealth of knowledge. There is hardly a day that goes by that I don't look up something.

Backings that will add draw weight will include sinew and other woods such as bamboo, hickory etc. You can back bow with just about anything that won't stretch. Other backings include natural fibers such as linen, silk, brown paper etc. These backings will not add performance (draw weight) but will protect the back from cracking or splinters raising up. You can also use synthetic stuff like drywall tape (did that on my daughters bow). I backed the bow that's in the clams above with brown paper (bought a roll at walmart) last night. I was going to back it with camo fabric but I got lazy. The first pyramid bow I built using this thread I didn't back. Have fun and experiment. Don't forget to ask questions on this forum. These guyz are SMART!!

Just 2cnt from another amateur.
Dave

Tom Leemans · « **Reply #135 on:** December 19, 2009, 11:35:00 AM »

David,
Not sure you're gonna reflex that set back out of her. That set is a result of cell compression. Usually, bending bows backwards, albeit gentle, damages the cells further and results in a failure at some point.

4est trekker · « **Reply #136 on:** December 20, 2009, 12:52:00 AM »

David: Your technique is correct, although like Tom said, it's too late in the game. You can reflex the limbs like that while at the same time tempering the belly, but I would do it just after you've gotten the bow tillered properly on the long string. Get the wood heated first, bend it slowly and clamp it, and then heat it some more. If you just bend it first without applying heat you can damage the wood at the cellular level. (p.s. You're first bow was fantastic! You should post some pictures of it here.)

Interestingly, I was reading back through Mark St. Louis' chapter on heat treating in the TBB Volume 4 looking for tidbits I may had missed the first 50 times (

) and I did find that he says heat treating can be used to remove set in bows. However, in practice this generally proves to be false.

4est trekker · « **Reply #137 on:** December 20, 2009, 01:00:00 AM »

I've gotten a lot of e-mails and seen a lot of pictures of guys building bows with this build-along. I'd sure like it if everyone who has built one would share their work with the Gang and post a picture or two of their finished product. If not a picture, then at least a short message saying you did and a brief description of how it went. I'd really enjoy hearing from ya'll! Thanks!

Bill Sagues · « **Reply #138 on:** December 20, 2009, 10:08:00 AM »

Okay - here we go.
I followed this excellent tutorial and built my first bow.
72" total length, 70" nock to nock, 10" riser, 2.75" - .5" width. I backed it with 3 layers of drywall tape and it pulled to about 40 lbs. at 30 inches. I shot it off my hand without an arrow rest and had a ball for about 150 arrows.
Then.....
A picture of the belly.

The back.

the "CRACK" :-(

Yep ... I was in the back yard shooting arrows into my target at 15 yards - and as I was drawing back one time I heard the slightest "crack" ... and that was it.

The good news is that I had to buy a 6" wide board at Lowes to find the grain I was looking for so I had about a ~ 2" wide board left from the original to start all over again - and so I have....
I will post when the next one it done - or broke; which ever comes first!

Thanks again 4est the great tutorial!

4est trekker · « **Reply #139 on:** December 20, 2009, 10:35:00 AM »

Great job, Bill! Thanks for posting.

If I may, the diagnosis for breakage is most likely due to the three layers of drywall tape. One layer is perfect and is all that is needed. The more layers you apply (i.e. the thicker the backing) the more you raise the neutral plane of the bow. This makes the backing do more of the tension work. A backing of this type is meant to prevent splinters from raising, not to go into tension, which would thus raise performance. Brown paper, silk, linen, drywall tape, rawhide, etc. are all backings that will deter splinters but NOT increase draw weight/performance. Sinew, wood, and bamboo backings are designed to carry the tension load, thus raising draw weight/performance. The first type of backings will be thin, the second type thicker.

My advice would be to use only one layer of tape and glue for a backing, if you use any at all. Again, great job and good luck with the second bow! At 2" wide, I would start with around 9/16" for the limb thickness. Good luck and happy building!

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