How far to pull a bend in handle bow?

[NorthHeart]

Im interested in seeing what a short native style bow can take, hopefully without it going "boom".  This bow is a pretty basic bend in the handle bow, no sinew.  Its 48" OAL, 4" handle slightly thicker but still bends, worked to a ring, rawhide backed, 1-3/16" wide the entire length, flat profile, pretty much looks like a board.  Its darn stout just getting it to 6" brace, and from there ive taken it out to 60# @ 20".  How far do you suspect it can be pulled?  Am i pushing it by going any further?

[PatM]

Not much is bending except the handle so you can probably get another 4 inches if you work the mid-outer limbs.

[Badger]

  If you just want to see what it can take you need to monitor the condition of the wood as you advance the draw length. You might also consider getting the outer limbs working. Almost all your bend is in the handle area. I see just a touch of set just outside your handles, that means that area has already reached its limit. You need to get more wood bending to take it further. If you are just looking for the point where it will fail then just keep pulling it and see where it fails.

[Drewster]

The outer third of your limbs don't appear to be bending.  I would get those moving next.

[NorthHeart]

Gentlemen here we are tonight, 65# @ 22".  Removed wood mainly from tips and a tad from mid limbs.  Appears to have taken more set.  Maybe thats just part of me pulling the bow as far as i hope too without breakage.  Or maybe im not tillering carefully enough. 

Is set from where you pulled the bow back and left it to thick in a spot, or too thin?  I know thats a noob question but im not fully convinced yet from the bows ive built.  Add in the fact that it was never perfectly straight to begin with(actually had some reflex but not perfectly even from even limb to limb) and its still less clear to me.

[Philipp A]

I am with the other guys, I think you still have to make the outer limbs bend more to go further in your draw without busting the bow.

[NorthHeart]

I thought i removed quite a bit of material from the outter limbs, but looking at my pics from last night they do still seem straight.

[Badger]

  Set means that you have already surpassed the bows elastic limits and have entered into a much less efficient plastic range. The areas that are taking set are areas that have too much strain on them because they are bending too much. Maybe you could back off the weight to 60# and get the other areas bending more.

[PEARL DRUMS]

Run a straight edge along the belly from fade to tip. Watch the air gap between the straight edge and the belly change. Where it is more narrow you mark and remove material. Its as simple as it sound. The gap should close slowly and consistently the last 10-12". 

[NorthHeart]

Badger thanks for explaining that, makes sense.  PD, that reminds me of that tiller gizmo some folks use.  Id like to get more familiar with how to use your straight edge method.  So the bow should be at brace when you do this right?  What if you remove wood via this method at brace but yet the limbs arent bending evenly...which takes precedence?

Tonight i worked the limb tips down some more and also removed material along the entire length of the belly, were talking just course-grit sand paper at this point. The bow is at 63# @ 23".  I shot it for the first time with the limb that has more set(right limb on the tiller tree) as the upper limb.  I figured that mimicked positive tiller.  I can only pull it to 21", and i was suprised that it had almost no hand vibration and was pretty darn quick with my 555gr test arrow!  Yes it took a bit more set, well now that ive pulled it to 23" i wonder if i call it a 22" bow for safety and call this one good, or do i work those tips down just a tad bit more?

[Del the cat]

Looks pretty good, but yeah, maybe the outer 1/3 - 1/2 of each limb could work more.
Mind, those short bows always tend to look a bit stiff in the outers, due to the way the string angle starts to pull at more than 90 degrees to the limb tip for extreme draw lengths. In other words it's almost pulling along the limb rather than trying bend it... dunno if that makes sense.
In the words of arguably the UKs most respected bowyers (when I was saying I might take some off the tips off a flight bow)
"You can always lose more weight off the tips" 
I think a reasonable/sensible limit is draw length = half the bow length.
I made a Yew sapwood short bow from an off-cut and then added a Yew heartwood belly strip just to see how far I could abuse it. It has the same sort of tiller shape. I even had some muppet on Facebook telling me it was all wrong 
It's pretty extreme, and can only bend like that 'cos its Yew... took a deal of set too, but it's a good demo' bow 
(It actually manages a 28" draw from a 47" bow)
Del
PS. My "standard" advice is pull it til it breaks then ease it back a tad

[burchett.donald]

   240m3srt,
                   This is far from perfect...but it may help and give you some idea, handle and middle bending with stiff outers...Try to get as much limb working as possible on these little bendy's...Hope this helps...
                                                                                                                                 Don
                                                                                                   

[PEARL DRUMS]

You can use a straight edge at brace or partially drawn on a tiller stick/tree, which is what you see in that pic. The bow is drawn about 18".

[k-hat]

Donald that's a great example, sexy sexy!

To the original question of how far a bendy can go, you must understand a little about AMO draw length(which is what most people use i think).  if you have your tiller tree  set up for this, you are measuring from a point 1.5" (i think) forward of the BELLY of the bow.  So a 28 inch draw would measure 28" from the BACK of a bow with a typical 1.5 inch handle.  If your handle is thicker(on the belly side), then your bow is going to be more strained, thinner handle = less strain. (this is actually true for any setup if you use the same one for all your bows, amo or not)

What this means is that a bendy bow that is .5" thick at grip, with equal length limbs as a bow with 1.5" thick grip, drawn to 28" feels 1" less strain (strain on the bendy bow at 28" = strain on stiff bow at 27").  Downside is it may also stack more near the end of the draw.

So if a good rule of thumb for stiff-handled bows is draw length max = limb length then bendy draw length = limb length +1"-ish (Generally speaking, all else being = ).
My humble 2¢ worth.
If you actually read all of this nonsense you are very patient, or a glutton for punishment.

[NorthHeart]

Your pic helps a lot Donald, i see the difference of the profile of mine and yours.  What was the final draw length, and how long overall was that bow?  Do you have a pic of it unbraced, did it take any set?

K-kat you make a good point about taking the width of the handle into account and ive often considered this, so i reckon on this bow which is pretty thin in the grip area im actually pulling the bow back closer to 22.5" in reality as measured from the back.  However, i would like some clarification on the last part of what you wrote.  Do you mean if your bow is 48" and bends through the grip that 25" would be a reasonable draw length?  Next, lets assume you have a 56" long bow with a grip and fade total of 7", then the draw length would only be 24.5"?  Also, i assumed you meant to divide by 2.  What happens when the tips are stiff do you subtract that from the overall limb length? 

I know factors like limb width, reflex, design and especially rawhide or sinew backing would affect things.  But i would like to have sort of a base formula to know going into each bow build.  Up to this point i've just been taking the overall bow length minus 10% divided by 2, and for sinew the overall bow length divided by 2.