Author Topic: Proper BH for longbows?  (Read 21004 times)

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Offline bigcountry

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Proper BH for longbows?
« on: June 09, 2008, 01:37:58 am »
For all your guys selfbow, is there a guideline for proper BH?  I use 5.5-6" for no other reason than thats what a bowyer told me to do on his bow.

I figured it would change depending how much one reflexed the tips or length, etc.
Westminster, MD

radius

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Re: Proper BH for longbows?
« Reply #1 on: June 09, 2008, 01:43:06 am »
i think that lower brace height = greater cast, but you want your fletching to at least clear the handle...

Offline adb

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Re: Proper BH for longbows?
« Reply #2 on: June 09, 2008, 02:00:45 am »
Make your brace height at whatever the bowyer suggests, for sure! I void the guarantee on my bows if brace height is above the suggested length. Lower brace height will improve cast slightly, but the bow becomes very noisy. Brace height is one important factor in tuning a longbow or recurve. Adjust it slightly, until you find the sweet spot. With flemish strings, usually 1 turn will adjust BH by 1/8''. Also, bowyers will measure it from different places. With longbows, I measure brace height from string to the back of the bow. With recurves, it's to the belly of the grip. I usually suggest a BH of 6-7".

Offline bigcountry

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Re: Proper BH for longbows?
« Reply #3 on: June 09, 2008, 11:13:14 am »
Make your brace height at whatever the bowyer suggests, for sure! I void the guarantee on my bows if brace height is above the suggested length. Lower brace height will improve cast slightly, but the bow becomes very noisy. Brace height is one important factor in tuning a longbow or recurve. Adjust it slightly, until you find the sweet spot. With flemish strings, usually 1 turn will adjust BH by 1/8''. Also, bowyers will measure it from different places. With longbows, I measure brace height from string to the back of the bow. With recurves, it's to the belly of the grip. I usually suggest a BH of 6-7".

Well, i am not talking about ones that bowyers build but the ones I build.   I usually measure BH for any bow recruve, compound, or longbow from grip to string.

I am just trying to figure out if there is a point where BH is too much.  I have been not going over 6" for my longbows, but have started reflexing the tips, and not sure if I should lower or raise that number.   I have been generally building 66" NTN 1 3/4" at fades 55lb-60 osage bows.
Westminster, MD

Offline Pat B

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Re: Proper BH for longbows?
« Reply #4 on: June 09, 2008, 11:54:31 am »
I use my fistmele for brace hight on my bows. That is my clinched fist with thumb extended. Basically you want your brace height to be high enough to clear your fletchings. You might adjust it a bit up or down to find the sweet spot.    Pat
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline bigcountry

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Re: Proper BH for longbows?
« Reply #5 on: June 09, 2008, 12:21:05 pm »
I use my fistmele for brace hight on my bows. That is my clinched fist with thumb extended. Basically you want your brace height to be high enough to clear your fletchings. You might adjust it a bit up or down to find the sweet spot.    Pat

Ok, so its that simple.  I thought the way some bowyers talk, you could so damage to a bow setting BH on longbows above like 7 or 8".  I guess you could because basisally, you will overdraw your bow with a high BH, which may not be made or tillered for a certain length and BH.

But if my thinking is right, on a bow that is 70" NTN (saftely handle 30" draw), and you draw only 29", it would be safe to adjust BH up to say 7" or maybe more?  Is my thinking right?  But for a bow that was tillered and built like 62" for a 28" draw and 6" BH, it would be dangerous to go over 6" BH?

Guys, I know these are silly questions, so I appreciate the patience.  Just new and only have 2 bows under my belt, and neither one are totally finished.
Westminster, MD

grantmac

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Re: Proper BH for longbows?
« Reply #6 on: June 09, 2008, 01:02:57 pm »
The problem with a drastic change in BH is that it affects the tiller in that same way as going from the long string to the short string. The higher the BH for a given bow the more the tips will bend.
Your also loosing valuble power stroke for a slight increase in accuracy. I personally prefer to have mine just slightly less then my fistmele.
     Cheers,
            Grant

Offline Pat B

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Re: Proper BH for longbows?
« Reply #7 on: June 09, 2008, 01:04:11 pm »
Brace height shouldn't effect tiller at all. When you draw the bow you always go past brace anyway. ;D Your brace height will effect the power stroke. The lower the brace the more stroke you have. There is a spot on each bow where your arrows fly best. That is different with each shooter also. If the brace is too high you don't get the power that is potentially in the bow and if it is too low you get the power but the arrow has to work harder to get around the bow handle...and the string will slap your wrist. :o
   Pat
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Kegan

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Re: Proper BH for longbows?
« Reply #8 on: June 09, 2008, 05:48:53 pm »
Hill suggested one inch for every foot of bow length. Makes sense if youbuild you bow so it's lenght is based on the draw length- the power stroke would be about the same, and the bow would be stressed about the same for different sized straight bows.

However, when you're shooting heavy arrows, the lower brace height is much prefered, and when you're shooting light arrows the high brace is more prefered. If I keep increasing weight while still using the same arrows, I'll have to increase brace height in order to maintane accuracy at long range with my next bows.

radius

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Re: Proper BH for longbows?
« Reply #9 on: June 10, 2008, 03:58:21 am »

you will overdraw your bow with a high BH, which may not be made or tillered for a certain length and BH.



I don't think that's true at all.  Your draw length doesn't change, but your EFFECTIVE draw will change.  Read Tim Baker on Bow Design and Performance.  If you have a 26 inch draw, and brace the bow 4 inches (very low, i think), your Effective draw will be 22 ".  If you brace it 6", then obviously you are only pulling it 20 inches to reach your draw length. 

If i'm not mistaken, this means that more or less units of muscular energy will be imparted to the limbs of the bow.  The energy required to hold a bow AT brace height is not part of the equation.  The proof of this is easy:  nock an arrow, but don't draw the bow:  when you let go the arrow either falls to the ground (loose nock) or stays clipped to the string (snug nock).  This, I guess, is why a bow braced at lower heights has better cast:  more muscle energy is available to propel the arrow.  But, as Pat says, the lower the brace height , the more you slap your wrist.