Author Topic: Ratio of Length to Drawlength  (Read 2487 times)

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Offline Christophero

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Ratio of Length to Drawlength
« on: March 02, 2010, 10:53:15 am »
You gentlemen will be a good source of knowledge.
A couple of years ago I was making a 72" 1/r sawn ash board bow for a tall friend but it came in too light.  Flipping the tips was tried but a pin not wouldn't allow it to hold on one side so I piked it down to 58" NTN and sinewed 2 layers on the back.  Then it got stored away until last night.  It will make a pretty little STIFF HANDLE bow with limbs of 1 5/8" from fades out 11" to 12" then gradually tapers to the nocks.  The handle is 6" with 2" fades.  It is currently pulling 39 lb. 6 oz at 22".
I didn't really expect it to ever be a bow to pull a 28" draw and not have excessive set.  I suppose it would be a good kid's bow or even a nice little horse bow with a short draw.  The queston that runs through my mind is how far of a draw can be expected and not have pronounced set?  Right now it follows the string about 1/2".
I appreciate your input.
Christopher

Offline Pat B

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Re: Ratio of Length to Drawlength
« Reply #1 on: March 02, 2010, 11:30:38 am »
Under ideal circumstances half of the bows length for the max draw length. Adding sinew to the back will increase the draw length a bit more but this is under ideal circumstances. You should be able to make 26" draw. Do a test and see if you can get a longer draw without adding more set.
  The set that is in the bow is probably from the original bow. The sinew backing should support the bow enough to help prevent more.  How much sinew did you add?
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Christophero

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Re: Ratio of Length to Drawlength
« Reply #2 on: March 02, 2010, 08:28:18 pm »
Thanks for the responce, Pat, and the refresher course.  I've kept my lengths 62" and up until this one and needed guidence.  Your are right, there was some set, not much, but some from before and the sinew, 2 courses I think, helped to pull it out.  Some more set is expected but I just don't want to see 2"-3" of it, if at all possible.
26" should be sufficient for those who this will be constructed for.

Offline yazoo

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Re: Ratio of Length to Drawlength
« Reply #3 on: March 02, 2010, 08:41:04 pm »
the handle seems a little long cut your handle down to 4in and the fades to 1 1/2 that will gain 3 in of wood that can help share  the load the extra wood bending will cut back on set
if you can shoot over them , they ain't to far

Offline Christophero

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Re: Ratio of Length to Drawlength
« Reply #4 on: March 03, 2010, 01:53:21 pm »
I would like to, Yazoo, but it was already formed from the design of the original bow to be make.  If it is cut down now the fades would be mighty narrow due to the handle width.

Offline Pat B

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Re: Ratio of Length to Drawlength
« Reply #5 on: March 03, 2010, 01:58:05 pm »
If you wait until the bow is tillered before you shape the handle you would be able to make adjustments as you go. The handle and tips are always the last thing I do before I shoot a new now in.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Christophero

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Re: Ratio of Length to Drawlength
« Reply #6 on: March 04, 2010, 09:03:52 am »
I've read your words of wisdom on that many times now, Pat, and incorporate it in to my builds, at this point.  This bow was started a bit over 2 years ago, though, when I was younger and more foolish. ;D.  A floor tillered hickory stave bow standing in the corner has a very rude handle/fade are presently and, as you suggest, will stay that way until it is much closer to finish.

Offline George Tsoukalas

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Re: Ratio of Length to Drawlength
« Reply #7 on: March 05, 2010, 10:00:40 am »
Double the draw and add 10-20% depending on the condition of the stave and your experience for an unbacked rigid handle bow of about 8 in. For a 28 in draw a good start is 67 in ntn. Jawge
Set Happens!
If you ain't breakin' you ain't makin!

Offline CelticArcher

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Re: Ratio of Length to Drawlength
« Reply #8 on: May 27, 2011, 11:13:07 pm »
i know this is an old thread, but here's my tuppence worth:
i made my last bow with a ntn length 2.3 times the draw length. can't remember where i read those figures, it was somewhere online, but they've worked well for me so i think i'll stick with them.

Offline crooketarrow

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Re: Ratio of Length to Drawlength
« Reply #9 on: May 27, 2011, 11:59:30 pm »
   I don't relie on ratio's I build the bow to the stave(design). At what ever draw leanth is wanted. I cut my handle in the begaining as I shape my limbs and keep shapeing as I go. I could see where cuting in handles last if your shooting off your knuckle Then it would'nt matter as much. But not if your cutting in a shelf.
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