Long string test

[Del the cat]

I'm a tad confused here.
When you say pull it to 20" you mean the 20" mark? Or 20" string movement.
I think I see where my confusion is coming from. If you are pulling to the 20" mark then the readings happen to be close.
Bur to my mind that's mere coincidence! If the long string hung down 19" then pulling to 20" wouldn't be much at all.
I think there's a danger of people believing long string measurement, which to me are totally deceptive.
From my previous result the string movement braced is almost twice what it is on long string! Yet when I do your test i get the same result as you!...
Mind it does tie in with my assertion that a "long string" should still be as short as possible to just slip on.
I think I need to lie down.
Del

[Badger]

 Del, forget about string movement and forget about tip movement just look at your tiller tree marks like you have a braced bow. Read it just like it is braced.

[Del the cat]

Del, forget about string movement and forget about tip movement just look at your tiller tree marks like you have a braced bow. Read it just like it is braced.

Yeah, that's ok, but only for 'short' long strings
My 78" long string I use on warbows   gives bad results on a 66" bow 
Del

[Badger]

  I agree, I admitted that, the closer the string the more accurate it is. But it does show an easy way to know present draw weight before braceing a bow, thats my only point. I don't like to brace them too strong and it takes some of the guesswork out.

[Del the cat]

Yeah, must admit, I prob' do brace 'em a tad early, dunno if that causes set, but at least I'm never under weight
Good to discus this stuff 'cos we all get a bit set in our ways (you only have to look at that shirt I always wear )
Del

[KS51]

There is some technical support for the results Steve is seeing.  While this probably won't be as true for recurved tips as for longbows, the basic geometry of the limb-string relationship would indicate that the long string (up to a point) would generate a force-draw curve that would be slightly shallower than the braced bow.

To explain:  Longbows typically use a string about 2-3" shorter than the NTN dimension, and when drawn, an idealized limb bends in a circular arc. Now, only the force that is perpendicular to the limb tip bends the bow limb.  That force directly related to the tension in the string and the angle of the string to the limb.  Then, the draw force is directly related to the angle of the string to the dirction of the draw.

A long string that is only a few inches longer than the braced string, doesn't change the geometry all that much, so the force-draw curve is close to the same.  As the long string gets longer, this becomes less true.

Also, what is different between the long and full brace string, is the compression that is put down the limb from the braced string.  This would be the parrallel force that is the result of the tension in the string at brace and the angle the string makes with the limb.  This initial compression diminishes as the bow is drawn and can get down to zero if the string goes to a 90 deg angle to the tip at full draw.

Ken

[George Tsoukalas]

Del, my method works for 26" with a string  about 1.5 x the bow's length. The weight reading with the long string at 10" will equal the weight of the bow at 26".
That is why I give it 5# over target weight with the long string at 10".

I got confused reading your post but saw 20" probably because I am tired.

For other than a 26" draw one can set up a proportion.

Jawge

[Badger]

  Jawge, if your bow is 66" long do you use a 99" long string?

[Badger]

      As long as the long string is not hanging down more than 8"  you can check your present draw weight anytime you like simply by pulling it down and reading it like a braced bow. If you like to brace your bow about 10# heavy just get your target reading about 4" before your full draw. I don't see how it could get simpler as long as the long string is not too long, anywhere from 4 to 8 inches slack will work fine. Read it the same way braced or long string.

[George Tsoukalas]

My long string is 75" and I use it on bows from 62-66" ntn. Don't make them longer than that usually.
Sorry about the confusion (mine).

Jawge

[Badger]

  Goerge, I am going to give you the old student to teacher challenge here. I have no doubt you have a solid system. You have succesfully located a sweet spot where you can get a fairly accurate reading of draw weight. and the amount inches of draw needed to get it. I feel the reason your system is flawed and requres some tuning is beacuse it is based on a false premise.

    The false premise is that the inches of string movement cannot be accurately gaged unless they are gaged relative to the geometry of the bow. By simply using a string about 1" longer than the bow you eliminate that entire step, you can read your weight the entire trip just by reading it like a braced bow. I was wrong about the length of the string not mattering much, by doing this test I was able to refine my own system. I always use a short long string anyway so wasn't really familiar enough with a long long string.

[George Tsoukalas]

Steve, I put the string on the nocks and the bow on the rope and pulley system. I stretch the string and mark its starting point. I then measure 10" down and mark that spot and slowly inch it down to the the ten inch mark all the while removing wood and checking the bend.

When I get around 5# over target weight at 10 inches, I get the back glassy smooth and string it up. This gets me at around 10# over target weight.

Reflexed staves and longer draws change the figures but this is just a ball park method to make sure the stave is not too heavy for stringing.

Next time I make a bow I'll check all figures.

My description of it has been faulty. My apologies.

Jawge

[George Tsoukalas]

In thinking about it, I am wondering if measuring the finished bow with the long string is really an accurate gauge of the  potential target weight of the stave at 10" with the long string.

There is really no way to measure the potential of the bow at that early stage of being a stave.

The goal should be to get the stave at around 10# over potential target weight before stringing.

The proof is in the outcome.

Time for bed, my friend.

Jawge

[George Tsoukalas]

One more thing, Steve. I did try your method years ago and it worked well. It will work better with a very short string for the long tiller. I never liked using the short string because I feel it puts too much stress too early on the stave.

The plan all along was to go just a little past brace height to  make sure stringing with a bow stringer would be easy combined with making sure the stave was not to strong for stringing.

I didn't like going much beyond 10" because strung bows behave differently from bows on the long string.

Perhaps you should try my method someday? You may like it.

Jawge