Primitive Archer

Main Discussion Area => Bows => Topic started by: DELTA_WOLF on May 15, 2019, 05:14:33 pm

Title: underdrawn bows
Post by: DELTA_WOLF on May 15, 2019, 05:14:33 pm
So i am noticing a theme with some longer bendy handle bows is that the bow isnt being drawn to its full length like a 56 inch bow not getting a full 28 inch draw, are there any advantages to a so called šunderdrawnš bow?
Title: Re: underdrawn bows
Post by: DC on May 15, 2019, 05:34:24 pm
Are you meaning that a bendy bow 'should' be drawn to twice it's length or was that just a coincidence?
Title: Re: underdrawn bows
Post by: Badger on May 15, 2019, 05:34:50 pm
 One advantage to shorter drawing bows is that they take less set and tend to be more efficient even though they may not store as much energy. Once a bow is overdrawn a couple of times that slight advantage is gone forever.
Title: Re: underdrawn bows
Post by: DELTA_WOLF on May 15, 2019, 05:49:34 pm
ok that makes sense, giving it a bit of room so it doesnt take set or lose performance
Title: Re: underdrawn bows
Post by: George Tsoukalas on May 15, 2019, 06:58:31 pm
Yes, or break. Jawge
Title: Re: underdrawn bows
Post by: Pappy on May 16, 2019, 04:56:35 am
Not sure where 28 became the standard for full draw,or any thing else is call under drawn or short draw ??  not many folks I know actually draw 28.I think it was just a standard set by mass produced bows. If I am building a bow for myself I never pull it over 26 which I consider full draw  :) Like Steve said no reason to bend it more than I need, on the other hand if building one for a person that draws 30 I never pull it over 30 which is full draw for them. :)
 Pappy
Title: Re: underdrawn bows
Post by: lonbow on May 16, 2019, 05:22:11 am
Books from the early 20th century speak about a standart arrow of 28 inches including the pile. That gives a draw length of about 27 inches. When talking about 28 inch arrows, it sees very easy to assume a 28 inch draw at some point!?
The draw weight was measured at 26 inches from the belly side of the grip and not to the back during that time. This doesnt seem to be a bad idea, because there are bows with flat and bows with deep grips. The distance from the nocking point to the belly side of the grip always stays the same.

lonbow
Title: Re: underdrawn bows
Post by: Del the cat on May 16, 2019, 06:17:35 am
Books from the early 20th century speak about a standart arrow of 28 inches including the pile. That gives a draw length of about 27 inches. When talking about 28 inch arrows, it sees very easy to assume a 28 inch draw at some point!?
The draw weight was measured at 26 inches from the belly side of the grip and not to the back during that time. This doesnt seem to be a bad idea, because there are bows with flat and bows with deep grips. The distance from the nocking point to the belly side of the grip always stays the same.

lonbow
Hmmm... not sure any of that is true.  :-\
If you bear in mind most archers would draw to the back of the bow and not beyond (the exception being flight archers).
The distance from nocking point to belly doesn't "always stay the same"... take a bow measure the draw length to the belly... glue a 1/2" extra to the grip/riser the draw length to the belly has now changed but the draw length to the back has not.
Apologies if I have misunderstood your post in some way..
Del
Title: Re: underdrawn bows
Post by: bradsmith2010 on May 16, 2019, 08:25:40 am
if I make a bow for myself,, I make it to shoot at 25 inches, that is the full draw for that bow,,no matter what the length,,of the bow,, (W
Title: Re: underdrawn bows
Post by: DC on May 16, 2019, 08:39:18 am
This is making me think that I could make a "better" bow by just tillering it/them to my draw length rather than 28". Is there an accurate way to extrapolate the 28" speed from a 27" measurement? Would just a percentage work? Would it be a fair assessment since I'm not actually bending the bow fully?
Title: Re: underdrawn bows
Post by: lonbow on May 16, 2019, 08:50:26 am
Thats exately what I meant, Dell! The distance from the belly side of the grip does always stay the same, because the every archer has his own drawing length. But you need a longer arrow using a flatbow, because the grip is deeper. Using a bow with a bending grip section, the arrow can be shorter. So I need 27 inch arrows for a longbow and lets say 27,5 inch arrows for a flatbow. The draw length stays tge same but the arrow length needs ti be different with different kinds of bows.
Title: Re: underdrawn bows
Post by: bradsmith2010 on May 16, 2019, 09:21:23 am
DC,, I am sure there is a way to extrapolate the 28,, Im sure Badger knows,,
but yes your bow designed for and shot at the shorter draw will be better than,, tillering to 28 and shooting at 27,,
I think you will be pleased with the speed you get at 27 ,, 26 or 25,, if the bow is designed for that,,
Title: Re: underdrawn bows
Post by: DELTA_WOLF on May 16, 2019, 09:26:18 am
oh, i guess i didnt really factor in the persons draw length, just what it is theoretically able to reach, ok makes sense now
Title: Re: underdrawn bows
Post by: Badger on May 16, 2019, 10:11:04 am
This is making me think that I could make a "better" bow by just tillering it/them to my draw length rather than 28". Is there an accurate way to extrapolate the 28" speed from a 27" measurement? Would just a percentage work? Would it be a fair assessment since I'm not actually bending the bow fully?

  DC, suppose you had a bow that was drawing 47.5#@27" and shooting at 186. If you drew the bow to 28" it would be drawing say 50# ( 2.5# gain) suppose your bow is about 75% efficient. That would put you at about 188 with a 500 grain arrow as opposed to 186 with a 475 grain arrow drawing 27". But keep in mind that extra 1" draw will also cause some set in most cases possibly eliminating your speed differential. If this were the case the loss of speed would be reflected when you went back to 27" and shot it again.
Title: Re: underdrawn bows
Post by: Woodely on May 16, 2019, 11:04:59 am
I tiller my bows to 28" and further so I know it will at least handle the extra pull to 29".  It just gives that added extra insurance in the hopes of not breaking or taking to much set.  My bows are 64" plus.
Title: Re: underdrawn bows
Post by: DC on May 16, 2019, 11:45:37 am
This is making me think that I could make a "better" bow by just tillering it/them to my draw length rather than 28". Is there an accurate way to extrapolate the 28" speed from a 27" measurement? Would just a percentage work? Would it be a fair assessment since I'm not actually bending the bow fully?

  DC, suppose you had a bow that was drawing 47.5#@27" and shooting at 186. If you drew the bow to 28" it would be drawing say 50# ( 2.5# gain) suppose your bow is about 75% efficient. That would put you at about 188 with a 500 grain arrow as opposed to 186 with a 475 grain arrow drawing 27". But keep in mind that extra 1" draw will also cause some set in most cases possibly eliminating your speed differential. If this were the case the loss of speed would be reflected when you went back to 27" and shot it again.

So if I was to tiller to, say 24"@40#, then test it. Then tiller to 25@40 and test. then 26 etc. If I notice a drop in increase, stop. At least I would catch it within an inch.
Title: Re: underdrawn bows
Post by: Badger on May 16, 2019, 12:07:50 pm
This is making me think that I could make a "better" bow by just tillering it/them to my draw length rather than 28". Is there an accurate way to extrapolate the 28" speed from a 27" measurement? Would just a percentage work? Would it be a fair assessment since I'm not actually bending the bow fully?

  DC, suppose you had a bow that was drawing 47.5#@27" and shooting at 186. If you drew the bow to 28" it would be drawing say 50# ( 2.5# gain) suppose your bow is about 75% efficient. That would put you at about 188 with a 500 grain arrow as opposed to 186 with a 475 grain arrow drawing 27". But keep in mind that extra 1" draw will also cause some set in most cases possibly eliminating your speed differential. If this were the case the loss of speed would be reflected when you went back to 27" and shot it again.

So if I was to tiller to, say 24"@40#, then test it. Then tiller to 25@40 and test. then 26 etc. If I notice a drop in increase, stop. At least I would catch it within an inch.

  My original no set tiller method that I still use on flight bows involves shooting as you suggested rather than monitoring the weight. It is much more accurate and sensitive, Super sensitive to even slight drops in efficiency. I just broke one a few minutes ago that was one of my best ever. I am really pissed. 51" long osage recurve. It came off the cawl with 5 1/2" reflex and right after unstringing still maintained 4 1/2" No change after sitting for an hour which is a very good sign. Testing was going great until I got to 24" which was full draw and it let go at a pin knot. I think I can fix it.
Title: Re: underdrawn bows
Post by: MattZA on May 16, 2019, 12:20:10 pm
Way to ruin a guys day, Badger ;)

I'm currently working on a stave the exact same length. Steamed static recurves into it and have tillered it to about the same length.

After reading your post I'm looking at it sitting in the corner and I don't have the stones to draw it past 24"  (--)
Title: Re: underdrawn bows
Post by: Badger on May 16, 2019, 12:34:14 pm
Way to ruin a guys day, Badger ;)

I'm currently working on a stave the exact same length. Steamed static recurves into it and have tillered it to about the same length.

After reading your post I'm looking at it sitting in the corner and I don't have the stones to draw it past 24"  (--)

  Usually on those short bows 24" seems to be about it before they start to show signs of fatigue, I think I could have gotten 2 more inches out of this one if it were not for the pin knot.
Title: Re: underdrawn bows
Post by: MattZA on May 16, 2019, 01:10:16 pm
Yea I'd be happy with 26" of draw. I'm considering a very thin layer of sinew for protection. It's also a setback and static recurve (some call it a 5 curve?) shape, so there's a lot of strain all round. I've got a bit of ostrich sinew lying around, maybe worth a try...

Interesting discussion about under drawing bows, though. It suggests that we all may be losing a huge amount of efficiency simply by the fact that we estimate our dimensions based on the intended draw length and weight. Sure, experience has helped us become reasonably accurate in our estimates, but it really is still guesswork. The closest to a formula we have is your mass principal (which I've read about 100 times, by the way. It's excellent).
Title: Re: underdrawn bows
Post by: willie on May 16, 2019, 06:41:08 pm
So i am noticing a theme with some longer bendy handle bows is that the bow isnt being drawn to its full length like a 56 inch bow not getting a full 28 inch draw, are there any advantages to a so called šunderdrawnš bow?

from a different angle, not all woods an bend the same "amount" before taking set, all else being equal.
so with a less than superior wood, a longer bow works better