Primitive Archer
Main Discussion Area => Bows => Topic started by: hook on December 16, 2010, 10:00:32 am
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Hey all,
I am about to finish a new bow, oak board. pyramid 2.5 inches wide and 68 inches long with the nocks 1/2 inch.
its a hair over a 1/2 inch thick at the fade tapering to slightly under 1/2 inch about 6 inches from the nock.
it appears to be bending equally and smoothly. it is also backed with silt fence (looks like black snake skin) we'll see how that goes.
so far i have built 4 bows all have broken. I realize thats part of learning so I'm not bitter...yet. just don't want to break this one.
QUESTION: I have not drawn it past 10 inches of string travel where it is 37# is there a way to estimate how heavy it will be at 28-29 inches?
i only have to sand the belly with 400 grit now.
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I guestimate with 3# per inch ;)
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Forgive me if I am misunderstanding your information and question, but if you have only drawn it to ten inches thus far, you're a long ways from wanting to draw it to 20-some inches. Decide what draw weight you want, then pull the bow only to that weight as you tiller, checking often. Each bit of wood removed will allow you to pull it a bit further before reaching that weight. You probably don't want to pull it further than the intended final weight, as this can cause pretty substantial damage. You might wind up picking pieces of that bow out of your ceiling, or the neighbor's yard, depending on if you are working inside or outside. ;)
Although, that said, if you are just curious about what it would pull at full draw based on #37 at ten inches, it's gonna be a lot if it holds up. I sure wouldn't wanna try and shoot it!
Let us know what you come up with.
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Yeah I'm with sweeney. Now with your question I agree with Jeff. If you are at #37 @10" now and you want to get to 28" you can estimate #3 per inch. That being said you could potentially get to #91 for the bow. What you want to do is pick your draw weight, if you want 50# pull the bow until you get to 50#. Right now that should be about 15", then once you're there just take small amounts of wood off evenly (since you said everything is bending evenly). Take off small amounts of wood evenly so that you go from 15" to 16" pulling 50# then just keep going that way. Then pull it to 17" and see what it's pulling, if it comes up at say 52# sand a little off until you come up at 50# then pull to 18" and so on. Also I typically try to shoot high, if I want a 55# bow I shoot for anywhere between 57# to 60# when I go to final sanding, that way after final sanding I get to my target weight.
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thanks, i forgot to mention that i have not braced the bow yet, still using the tillering string. great explaination stingray! the little lightbulb in my head just came on. I am all set up now with a tillering rope/pully system and a cheap scale. 14.95 (its a handheld luggage scale) should i try to low brace it now?
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If you have 10" of tip movement you should be ready for a short string and a low brace height of 3" or so...just enough so you can see how the string tracks and if the limbs are bending evenly and together. Be sure to exercise the limbs after each wood removal but don't pull it beyond where you have tillered it to.
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yes get it off that long string ont o a short one
like Pat said,about a 3" brace height for now
if you want a true impression of what the limbs are doing you really need to get it on a short string
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If you're only pulling 10 inches on the long string, I wouldn't worry about the 400 grit just yet ;) You've still got a ways to go grasshopper!
If you follow the advice you've gotten so far, that should keep this one from breaking. From my limited experience, as Stingray mentioned, the most important thing is to choose your final draw weight before you even start tillering (keeping in mind what the wood you are using is capable of - certain woods are not suitable for more than 60-ish pounds), and not exceed your desired final draw weight during the tillering process. At the very least, pulling too hard will cause excessive set, and worse could cause your bow to make that sound that you don't want to hear :)
Good luck, and let's see some pictures!
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thanks for the input, from all
I want to get one good shooter and then concentrate on some tackle and then....i'll quit and never ake another one::) (right)
i will try to be more patient and solicit more help if thats ok with you all, i picked a pyramid design because i read that they are easy to tiller
and somebody made one on you tube in a hour or something stupid like that but I am learning! I have this really nagging desire to make a bow
that shoots arrows that hit the things you aim at. primal? yes. fun? yes. rewarding? yes. So thanks for the advice and encouragement to all.
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...made one on you tube in a hour or something stupid like that ...
Dang...I'm still putting 30 hours in a bow, guess I ain't nothing but a rank amateur after only 150 or so successful bows.
Someone on here once posted a good philosophy for tillering..."Softly, softly, catchee monkey". If you are tillering with 400 grit I guess you are getting the "softly, softly" part down pat. *grin*
I agree, you are probably at the short string stage of tillering, so take your time but you might want to try something a little rougher grit...say a scraper blade at this point. Keep us posted!
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well, its a bad time of year to try to get bow work done (except Christmas bows) but last night I removed the silt fence backing because the plastic just didn't bind well to the wood with TB3. I am going to apply a natural backing, probably burlap because I have some although the last burlap backed bow snapped clean and pieces of wood flew so maybe I'll try some linen this time.
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I agree with sweeney also. If this is what your doing this is why your other 4 bows broke. Build a tilling tree with a scale with it. Tiller the weight you what to the draw leanth you want. No trying to estamate thickest of your wood to weight.
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ok, I now have it at a 4" brace height. My question is:
is the draw length the same on my tillering tree or do i have to somehow adjust it for a 6 or 7" brace height?
in other words: can I still go by the measurement marks on my tillering tree at a 4" brace height?
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draw length is the same...it is measured from the bow regardless of brace height.
Power stroke is draw length minus brace height...IE the length the string travels from full draw back to brace after the string is loosed
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Any chance of posting some pics? They're worth a thousand words, after all, and the folks here can tell a lot (and help a lot) just by looking.
Frode
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frode,
unfortunatley my camara takes pics that exceed the size limit here. I don't know how to get them sized down to post them. I would love to know!!!
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Almost any picture editing program will resize pictures. I know HP Image Zone, which comes with all HP printers, will do it. I suspect your camera has a resolution setting as well. Set it to 640x480 and the picture it takes will be good to go. I don't do that though, I use free software called Gimp. Load it, then bring up your picture in gimp, select image -> scale and then make the longest dimension 640. Do a save-as to a new file name and you're good to go. Other alternatives are to use a picture site like Photobucket which will give you a low-res URL to use for web posts.
George
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hey guys,
Just a little update. I added an 1-5/8" reflex to the tips 6" back from the tips to try protect the bow from set. I put it back on the tiller/pully system which I improved last night to get the bow up to eye level and a decent back ground. one end (just in the bent part of the reflex) bent more than the other so I sanded the stiffer one to get it to a closer match, its not perfect but I think I will make it my bottom limb rather that take it too far and screw it up. It is pulling 55# at 28 inches and I was shooting for 45-50# I think i am finally going to end up with a bow that actually shoots arrows!
with georges advice i might even be able to post some pictures when i get the finish and handle on it! whooo-wheeee!!!!
thanks guys
john
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Check the resolution setting on your camera. Set it to the lowest setting and it should give you pics at 640x480 which will download right on to PA.
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Hey guys I have just got the stain and sealer on. I am ready to put the arrow rest and leather wrap on the handle.
The arrow rest I have chosen is glued 1/8" thick leather. it is 3/8" thick where the arrow will rest, tapering down to 1/8 at the bottom, 3/4 wide, tapering to 1/4.
its sort of an elongated guitar pick wedge.
is there a specific spot where this needs to be glued? is it to big? how much space is needed between the top of the rest and the angle of the fade?
how do you get the leather wrap (solid piece, not narrow winding) to conform around the rest?
thanks,
john
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I just got the handle laced and wanted to see how the arrow rest worked. braced it to 1" below height, pulled it gently a few times, went outside, nocked an arrow, pulled back slowly and smoothly and I heard one crack and now have a 4 piece take-down bow. WTF?
I dont know where it failed first. I am guessing it was the handle. my riser was only 6" with steep fades I also think I had a couple of grain run-offs. I went back to lowes and now have another 1x3 with a 9" riser glued and will try again tomorrow. just when I thought I had a shooter! I am really getting torqued!!!!!!!!! took my time and everything!
I hope the pics show up!
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I don't think it was a bad design. I just think I picked another bad board. Its tough to see the grain on the sides without getting the right glare and squinting alot. sometimes those open pores on oak look like grain. H-D and lowes just have crap to choose from. is there anywhere to buy an actual straight grained board for bows?
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Dang, that's rough, it blowing when you're completely done. I always finish my tillering before doing any handle work. Then I complete the bow and shoot it some before putting a finish on it. All that to reduce the pain if it blows up. I've only had one blow as completely as that one did, pretty spectacular (if it weren't for all the work that went into it). :(
Good luck on your next one.
George
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Bummer Hook. Don't lose heart, though. My first was fiberglass tape backed oak with a hinge and 35#. I then proceeded to break 8 or so bows. To be honest, I'm not a fan of "superstore" oak boards. My first successes came with hickory boards. They are very forgiving to beginners and make great bows. I found my first hickory boards at a shop making crown molding. Then I looked for hardwood dealers in my area and found much better quality with straight. To get boards like that now I've got about a 45 minute drive, but it's fine.
Couple of questions:
Where are you located? How well are you sanding the back and the backs edges? Did you end up putting a linen backing on this? It would have needed it - there is quite a bit of run off. Would you consider trying a D bow - it's a personal thing, but I found them easier to begin with. Post pictures as you go with your next round.
Keep the faith, man. Your going to get your shooter very soon, I'm sure.