Arriving at a desired draw weight

[JRFaulk]

Lurk a lot here, don't post much.  Lately I've made 3 osage bows (last 3 months), about 8 bows total.  Have been hoping to have a new hunting weight bow in time to practice with it before fall.  I need some tricks/tips for arriving at a desired draw weight.  I think I have narrowed my problem to, by the time I get the bow bending evenly, it's too light already.  Any advice, other than keep trying?

[PEARL DRUMS]

Sounds like you need to get a better feel for floor tillering. Grab a finished bow and flex it on the floor as if floor tillering it. Get an idea of what that draw weight feels like as you flex it. Try to stay above that as you build your next one, well above it. There is a threshold in regards to over-stressing a bow. You have to somewhat stress it in order to get enough tip movement to judge the floor tiller. If you pussy foot around too much worrying about damaging the wood you end up with 30# bows you don't want.

[jeffp51]

Decide what weight you want before you start, then put it on a tillering tree way before you reach that weight--don't floor tiller too far to begin with.  on the tree, start with a tillering string just longer than your nocks and pull with a scale.  Never pull beyond your draw weight.  Work very slowly and fix problems early before they become big problems.  When it bends a little better, shorten the string to a 1 inch brace and repeat.  By the time you reach full brace (don't hurry the process) you should be nearing full draw, still never pulling past your draw weight.  Take pictures drawing it in your hand as you approach full draw.

People who have made a lot of bows (like Pearl Drums) can go from floor tiller directly to low or full brace.  If you put it on a tree earlier, you can see it better at first--Eric Krewson's tillering gizmo is also a big help, because it shows the flat areas.  As you get better, your eyes and your hands will tell you all you need to know, but to begin with, you need lots of cheats.  if you post here, many will be willing to offer an opinion to help you see better.

Did I mention going slow?

welcome to PA.

[Del the cat]

Start pulling it on the tiller early and ALWAYS pull to full target draw weight unless you see a problem with the tiller before hitting full weigh.
By "long string" I mean one that you can only just slip onto the bow without bending it.
It's as simple as that.
Had a bloke hoping for a warbow of over 100# he was pulling it to 70# during tiller... guess what it ended up at?
If you want a 50# bow you gotta pull it to 50# !
Del

[bradsmith2010]

great advice from above, and yes keep trying, the more experience you have the more successful you are at hitting weight,,
 

[wizardgoat]

I'm like Pearly, I rely on a very accurate thickness taper and a good floor tiller.
More often than not, floor tiller, strait to full brace. I don't need to tug away on a
long string to know a thin spot is weak and a thick spot is stiff.
I like to get my tiller sorted out as early as possible, and slowly open up those stiff spots as
you ease it back. I try to come in 5-10# heavy.
Do small wood removals and check your tiller constantly until you get a good feel for what
results you get with how many scrapes your taking.

[willie]

floor tiller or low brace on a tree, whichever you prefer. I look very closely at the bend shape (and do most wood removal) with the bow around brace height. The work planned for longer draws is limited to minor bend shape corrections and even weight reduction if necessary

[bradsmith2010]

yes you wanna get that bow bending even early on,, you dont want to hit full draw and have major corrections to do,, thats when you loose your cast,, make hinges, and miss weight,,
if its bending even early on, ,,, you can go slow and not strain the wood and hit weight,, making for a great shooting bow,,

[jeffp51]

floor tiller or low brace on a tree, whichever you prefer. I look very closely at the bend shape (and do most wood removal) with the bow around brace height. The work planned for longer draws is limited to minor bend shape corrections and even weight reduction if necessary

Yes--ideally you should have your bend looking how you want it before you get to full draw at your target weight  the last few inches at least should be mostly weight reduction while still checking for even tiller.

[JRFaulk]

Thanks for the tips, everyone.  I was really getting frustrated, but now I have several ideas to work with/on. I really appreciate the help.

[Badger]

  Another extremely common reason for coming in light is that bows will often take unexpected set in the later stages of drawing, usually the last few inches. This is why it is so important to draw it to full draw weight earlier on in the process.

[High-Desert]

+1 on everything said above. But to emphasize learning to floor tiller. I didn't understand this concept at first and it made no sense. I thought it was use to get it bending, it is, but as well and seeing your tiller, it just takes a different eye since you are viewing it from along the limb. Get good st it, and you may not even need the ever use the long string, except maybe once for verification that thins are even. You can put your low brace or full brace string on at pretty high weight. Since it's only bending a little compared to what it will be. Once you can comfortably brace it, do it. if you are blowing blood vessels, then it too strong.

Eric

[Eric Krewson]

If you use a tillering gizmo on the long string at about 3" of bend and correct the tiller until your pencil no longer makes a mark on either limb you will come in way over poundage when you get to the short string and normal brace. I don't do precision floor tillering, I just get things bending about evenly and go to my long string and tillering gizmo.

I am working on a BBO using this method and my problem is how to get rid of all the excess poundage. I have three more inches of draw to get to and 12# to get rid of.

[upstatenybowyer]

Fantastic info above from guys who really know what they're talking about. I would recommend copying it all, pasting it onto a Word document, printing it, and keeping it with you as you tiller your bows.

Like goat said, an even thickness taper is key. I think knowing the right starting dimensions for the wood you're working with is key. For me that took a lot of trial and error. Once I got that, I was able to rough out a bow to very close to the desired draw weight (about 10# over) before even bending it.

Then like Badger said, I start pulling it to the target weight right away, which will be 10 inches or so shy of the targeted draw length. I rasp to keep an even bend from there until the target draw weight occurs at the target draw length. This way you don't over stress the wood. 

[George Tsoukalas]

There are build a longs on my site.
http://traditionalarchery101.com
Jawge