Build Along ( building by mass)

[Badger]

I went a head and glues some nocks on with super glue so i could keep the buildalong going, here is a pic on the long string one drawn to about 25" and the other with the string hanging down to about 7". The long string will not give an accurate assessment of the tiller but it will give a relatively accurate of where the draw weight is if it were braced. Doesn't seem to matter that the string is loose. If the bow were braced the outer limbs would be bending more than they are now. I am still at 22 oz and the bow is pulling 80# at 25", I am looking for 80# @29" or 30". This is close enough to brace the bow. The outer limbs seem very stable and are not showing any sign of lateral twisting so i will take advantage of this and narrow them a tad more reducing mass a bit further. I can see in the photo that the outer limbs are still stiffer than they should be but I wont attempt to final tiller or tiller much further on the long string. I ned to stop and make a string now. Steve

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[Badger]

   Here is a pic of the bow at 25" but at a low brace height, notice how much more the outer and inner limbs are bending with the bow braced. The draw weight is still reading about the same 80# @26". Doesn't seem to matter if the bow is braced or the string is hanging down loose 4" or 6" or 15 " it will read about the same at a particular draw length, but as demonstrated here the tiller cannot be judged unless the bow is actually braced, the higher you brace the bow the more the outer limbs will bend. The tiller on this one will just need a little bit of work and I will need to stretch it out to 30" from 26". I don't have any linen or fastflight string and the b 50 is really a pain to use as it stretches so much I almost get a hernia trying to brace this thing. So far the bow has not shown so much as a whisper of set even when it is first unstrung so I feel confident I have the proper amount of mass in the bow to complete it. It is weighing in at 21 oz right now with 1 oz to go and 4" of draw, right on target if she don't break!  Steve

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[Badger]

      Something I am kind of tempted to do with this bow. In my chapter comming out in TB4 I have a section on peaking and tweaking. This talks about learning to reecognise when you have a wood specimen that will allow you to push the limits a bit with the reward being a very high performing bow, the risk being a broken bow. One of the main things I am looking at when evaluating a bow for possible peaking out in performance is a lack of set or softening of the bow. If I were to break this bow I wouldn't be out anything as I can't draw 80# anyway. I am considering just fine tuning the tiller on the bow and then proceeding to draw it out further and further and if possible out to about 31" or 32". I would do this 1" at a time with a lot of excersize on the bow at each new 1" increment. After each additional 1" was gained i would unstring the bow and monitor and note the set. Once the bow started to show signs of set i would call it quits or possibly just call that max poundage and start tillering so the weight did not gain as I gained additional inches of draw. This method gets the most out of a bow. I feel like I could easily get 100# out of it as I have allready drawn it to 85#. Not even the slightest sign of set even when measured right after unstringing. What do you guys think? Should we go for broke? Steve

[jwillis]

Pun intended?... maybe just take it to "max." hehe  Jim

[Badger]

He!he!   When I say broke i mean broke!!! LOL. Steve

[DanaM]

Might as well live life to the fullest. Of course its your wood so as ya see fit.

[markinengland]

Steve,
Interesting to read this thread. Not sure I have my head around the figures side. I look forward to reading TBB4 to see if I can make sense of it.
I weighed the laminated Ipe/Boo bow I am making. 78.5 inches ntn, 1 and 1/16th wide at the handle, 1 and 1/8th deep. nocks 3/8th wide and 9/16ths deep at the nocks. The lims are wider than they are deep mid limb. I am aiming at 110lbs at 30 inches. I am getting a little bit of set mid limb so relfex at the handle is about half an inch. Weight is just about 30 ounces.
I feel I have more wood to come off at the tips and handle. I want the relfex to pull out to stiff at brace and basically full arc at full draw with a slightly stiff handle.
I'd be interested to know what the formula suggests. The bow that broke was conforming quite well to your forumla but bent too much at the handle suggesting that that part was too light and the tips and rest of limb too heavy. for my last bow you suggested 34 ounces and I am four ounces under, though I don't really intend this one to have a stiff centre section like the last one.
Mark in England

[Rich Saffold]

Oh that will make 100#'s easily Just keep those fingers away when it hits 150 on the scale. I'm guessing one of them might still be throbbing a bit..

Bamboo bows just don't explode like selfbows do.. I start enjoying that a bit too much...

You could probably tiller it into a hula hoop if the right wahine was watching

Rich-almost friday!

[mullet]

  Ohhh, I hate seeing them break. I say take it to max.

[PatM]

"It looks longer when sewed back on". Physicians now universally use the term "the Bobbitt effect" for that phenomenon 
 Pat

[Badger]

Mark, if you go with a full warbow arc of the circle type tiller between 27 and 30 oz would be good. 29.5 is what it suggests but I always nock off up to 10% more for a backed bow.  Something else to think about, the formula will give you a good weight for what you describe but it knows nothing of demensions, do you feel a 78" bow that is 1 1/16 wide will be stable enough when the depth exceeds the width? Probably not the most stable design. In a case like thsi the formula is silently suggesting to change a design or a wood that is being used for a specific job. Often changing the length of the bow or the tiller will bring a bow right into a nice stable design and still well within acceptable mass limits. Steve

[Pappy]

Dang Badger,do you ever sleep.You are either out late or up early like me.Good info and like some others I am still trying to get my thick head around this,I'm going to keep trying.I do already do as you said about between every inch of draw measure the amount of set and when it starts and don't recover in a short time I start looking closer at my tillering methods.It has really helped
as far as set and string follow. Thanks for sharing.
   Pappy

[Badger]

Pappy, I don't sleep a lot. I work swing shift but still wake up early as if I work days. I usaully take about a 1 hour nap right before I go to work. I have been trying to figure out a better way to explain it where a guy could figure it out roughly without using a pencil and paper. I think figuring out an easier way to express the formula should be my next project. I always like to think of it as starting from zero. A 54" bendy handle bow with a 27" draw would be zero plus draw weight. If the working limb is equal to the draw length ( one one limb) it has zero mass value, if the draw length starts to exceed the working limb we add mass, if it gets shorter than the working limb we remove mass. Setting the tips into reflex adds mass. When we stiffen up the handle and fade area or center of the bow we also shorten the working limb area. So the draw length has a direct relation to the handle and fade area when figuring the mass. When talking about mass on a bow we are talking about 90% of it being in the width of the bow. I will try to figure out an easier way. Steve

[Badger]

Well, I finished her off at 90#@28" feels real good there and just starting to take a whisper of set. limbs are still straight but lost that 1/2" reflex which come back after setting a few minutes. I think she has flight bow potential, Will sand her down and post her this weekend. wants to torque to the side just a little bit which I dont like but I think I can correct that in the nocks. Steve

[markinengland]

Steve,
I have found that with narrow and slightly unstable bows a bit of careful but brutal sideways floor tillering in the brace shape seem to help. Just push the limbs the way you want them to go, draw, look at the way they are, sidewyas push again and they seem to get the idea after a while. Sometimes they need reminding in the same way but it seems quite effective.
Any idea what you think my bow's mass should be, see earlier post on this thread.
Mark