new bow # question

[hook]

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.

[HoBow]

I guestimate with 3# per inch 

[sweeney3]

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.

[Stingray45]

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.

[hook]

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?

[Pat B]

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.

[sailordad]

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

[Cameroo]

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!

[hook]

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.

[JW_Halverson]

...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!

[hook]

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.

[crooketarrow]

  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.

[hook]

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?

[aznboi3644]

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

[Frode]

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