Handling of reflex when tillering

[BigWapiti]

I'm currently working a VM stave that has quite a bit of reflex - about 3" on each limb.  I have it floor tillered, but its still holding all that reflex.  as I've been tillering and setting on my tree - I started to see how that reflex might be working against me.

There is quite a bit of leverage that I'm working against, getting it to bend.  I still haven't tillered it down enough to get it to bend past the handle while staying under my desired weight.  I'm concerned that I'll finally get it to that point and lose a lot of poundage.

How do you recommend tillering a high reflex stave?  Should I have steamed a lot of the reflex out of it first?  I'll post a pic as soon as I can.  I was excited thinking I'd have quite a slinger with this one - i'd sure hate to take that zing out by actually removing the reflex.

Whatcha say?

[Badger]

     Big, if you can keep about 1 1/2" of that reflex you will be in good shape, if you loose all of it the wood will be crushed pretty go but still make a decent shooter. When I have a highly reflexed stave I either rely on long string tillering till I hit a point I can brace it or just keep floor tillering till it feels about right to brace. A reflexed bow has quite a bit of tension on it just getting it braced and can fool you eye if you are not used to them, just study how it is bending as much as you are studying the shape of the bow as you build it. The shape can look right but it might be bending too much in one area. Steve

[BigWapiti]

Thanks Steve,
Sounds like my concerns are in the right line of thinking.  My worry is that as I tiller her down to brace, using the long string or floor tiller, that I'll reach a point that to get it to brace will then reverse the weight.  I really have no way to try to better explain this.....  sigh.   let me try again...

right now, using the long string on my tree - If i pull just an inch, it quickly gets to my target draw weight.  If I keep tillering, it continues to bend more while staying under my desired weight.  BUT, I have a feeling that I'll soon reach a point where as the reflex comes out of her, the weight will drop VERY quick, creating a very lightwt draw bow....  man this is hard to explain.  I think leverage comes in to play with the reflex.  I have a tough time keeping from over drawing during tiller for fear of that break even point hitting fast.

I think I'll give up there and see if its making any sense to you.

[DanaM]

Try badgers mass theory, the weight of the bow will help you know what to expect and when.
This is the best way I know of short of experience.
Also pay attention to the limb thickness you've made a few other bows from VM so you should have an idea
of what thickness you need to be at.

[BigWapiti]

yeah, the thickness is what has me concerned.  I started realizing that I'm already below "standard" thickness for a VM of this draw weight.  I suppose this is how I could have better explained my delemma.   It seems already to a point of limb thickness where it should be bending to draw weight (50#) and I'm not even getting it to bend to brace yet.

Mass theory?  I'm all ears!

[DanaM]

http://www.primitivearcher.com/smf/index.php/topic,5127.0.html

Here's a thread badger started explaining it somewhere in there is a excel spreadsheet.

He also has a chapter in TBB Vol 4, good reading.

For instance for a stiff handled 50# @ 26" 68" NTN bow with no initial reflex it should be in the range of 20 to 21 ounces
and that is irregardless of the wood type, you just adjust the width based on the woods ability.
Same bow as above with 3" of reflex and the mass jumps to 22ounces, that much reflex puts more stress on the limbs
therefore more wood is needed.

Its a great tool, a little confusing at first
but stick with it and it gets easier

[NOMADIC PIRATE]

I always had problems with highly reflexed steves, tricky they are for sure, easy to go under weight, ...did that before, I have a 6" reflex stave from Gordon, it's worked down quite a bit, but can't find the courage to start bending it,...it scares me.

I will be following this thread to gain some tips from the exerts , for sure

[Gordon]

Vine maple is about as extreme an example of tension wood as they come. It might look straight when you cut it, but some staves will just curl right up during the drying process. 3-6" of reflex is fairly typical . But it is quite managable if you understand the wood. Much of the reflex will pull out during tillering, mostly on the short string. The way I deal with the reflex is try to get the bow on the short string sooner than later. That's because the tension induced reflex will make the bow seem heavier than it really is and when the reflex finally gives way (and it will happen almost all at once) the bow will drop in weight considerably. I try to get the bow on a short string when the tips are moving about 12". Obviously then it is really important then to try to get your tiller as squared away as possible before you subject the bow to the rigors of the short string. I also exercise the crap out of vine maple after every wood removal - my goal is to try to get the wood to give up the reflex while I still have enough wood to hit my target wieght. But don't get carried away and pull too much weight or the bow will eventually take a set. I don't pull more than 5# over target while I still have reflex, and then no more than target when the reflex is largely gone.

Oh, and don't bother trying to steam out tension induced reflex because it will just come back when the wood dries.

Hope this helps.

[BigWapiti]

Thanks Gordon, it does help.  But the issue I'm finding with this particular stave is that 12" of pull seems like a long way off yet.  I can't even get a couple inches and my limbs are already way thinner than I would expect.  I can't seem to think that I have a stronger piece of wood, I think its more in the reflex.  I put this stave in a jig to hold it from taking on too much reflex - not even sure it worked - as you say, VM seems to want to flex to where it wants, no matter what you do to it.

I'm just not sure how to get it to 12" of pull, let alone to flex past the handle.  Crazy stuff, but I guess thats why I'm loving it.

[Gordon]

How thick right now is the wood at the start of the fades. Is the bark off or on?

[BigWapiti]

Bark is off, its been off since just after it was cut, which was this past Fall.  I had only split it after taking the bark off and just recently roughed it out and started tillering.  I'm not at home, but I believe the thickness at the fades is somewhere around 0.7" - which from my two other VM bows, is about right on for the 50# class wt bow (your thoughts?).

I really need to show some pictures, but having had my home laptop crash - I've not been able to get pictures from my camera. 

((which, btw, is why I haven't finished publishing your hazelnut build-along yet.... the laptop crash took all that work away -  I'm working to recreate it though - pout))

[Gordon]

Yes, that should be about a 50# bow. You might try hanging a 50# wieght on it for a few hours - you have to pull that reflex out before you take off much more wood.

[BigWapiti]

Thanks for the idea Gordon.

I like it - I'll give it a try.  I might start with hanging a little lighter weight since my target is 50# - or do you think I should be worrying that?

[Gordon]

50# should be fine, but put a stop under it so the limbs are not overstressed when the reflex begins pulling out.

[BigWapiti]

Will do - I'll post back to let you know how it works out.

hmm, any thoughts on how much reflex I should try to pull out?  That is, how far should I let the weights go before stopping them?  If I want, say, 2" of reflex out, would you double the distance to drop?  or make it 2"?