D/R tiller- the outer limbs

[upstatenybowyer]

Hi guys,

So I've been thinking a lot about how the outer limbs should look on a D/R bow that has a lot of reflex there. I keep going back to a comment Badger made on one I posted a little while back. He said the FD was about as good as I could get given the unbraced and braced profile. In that FD, the outer limbs looked straight, and others thought they should bend more. I decided to leave them as they were.

To me it makes sense that the outer limbs should look straight at FD if they're highly reflexed while unbraced. What are your opinions on this?

Here's one I'm currently working on that's shooting very fast and holding the reflex very well. Should the outers bend more? my gut says no.

[DC]

Hi guys,


To me it makes sense that the outer limbs should look straight at FD if they're highly reflexed while unbraced. What are your opinions on this?

Yes in a general sense. Highly reflexed is kind of a vague term. I think it's tied in with other things like bow length and draw length. The outers on an RD are basically working recurves and how much they unwind depends on how much they were reflexed when you started tied together with how far you pull it and how long it is. A short bow with a long draw length will go past straight and a long bow with a short draw length won't quite straighten out. My 1cents worth.

[SLIMBOB]

I’m no expert on these reflex deflex bows. Matter of fact I’m puzzled at times by them. For what it’s worth, that looks damn good to me.

[Badger]

  This is a real common problem when there is too much bend mid limb unbraced. I prefer to see the bend much more gradual and increase more as it nears the tip in the unbraced profile. This design is hard to tiller out. They often get too thin in the mid limb and then start collapsing. You may have to get a little more bend mid and outer limbs.

[bradsmith2010]

Its hard to gauge if the limb is working evenly...I am guessing if the taper is perfect,.the tiller is pretty close...and it will look how it looks,,.

[upstatenybowyer]

Thanks all. Steve, That makes a lot of sense. Sounds like I may need to adjust my caul to make the mid to outer limb transition a lot more gradual.

[Dances with squirrels]

Your outer limbs aren't highly relfexed. Your mid limbs are.

My advice... read what Badger and Brad said until it really sinks in.

Sometimes, the common problem Badger mentioned about there being too much bend midlimb of the unbraced blank is because it was glued up without pretapering the limbs. But it will still make a good bow if...

You can make it whatever profile you want, and tiller any part of the limb to work more or less as you see fit. But as you judge it, always compare how each part of the limb flexes to how IT looked unbraced. In other words, fight the mind's eye's inherent want to see that classic arc of a circle.

As Brad said, if you are meticulous about accurate width profiles and thickness tapering, in general, the bow will try to show you how it should look as its braced and flexed. You can vary from that a little, but don't fight it too hard trying to make it something else. The more you do, the more you risk what Badger mentioned, getting too thin/weak, causing set, collapsing in the overworked area.

Badger said, "They often get too thin in the mid limb and then start collapsing." They do. But this is not simply because that's where most of the reflex was glued in, but rather because folks try to make it something it doesn't want to be. They try to make the drawn profile look like the drawn profile of a different type of bow, usually a straight bow... and in order to get that 'inappropriate' shape, that midlimb area must be made too thin and weak.

I too prefer the reflex to be gradual and even from midlimb to the tips, or gradually increase.

[upstatenybowyer]

Your thoughts are truly appreciated DWS. I am definitely going to meditate on what Badger and Brad said. I've been slowly learning the underlying concept of what you guys are talking about, however, it's the nature of who I am that I end up really understanding something only by doing it the wrong way a million times first (a blessing and a curse if you ask me).

I think the way the bow above looks now is close to as good as I'm gonna get it, but going forward, I'll really try to spread the reflex out from mid limb to tip.

[bjrogg]

I've still never tried one of these Jeff, but I find these comments interesting. I think the tiller on this bow looks like how I'd probably make one. I do like the idea of carrying your reflex slightly more gradual and carrying it closer to the tips. I suspect your outers could be working just a bit more than they are right now, but like I said I haven't done one of these yet. Nothing like learning by doing and making mistakes along the way.
Bjrogg

[Badger]

  Upstate, yours is not too bad and still plenty workable, I just think your bend is slightly abrupt. On the plus side if you complete your tiller without a hitch it is a very fast profile. If the other limbs end up too stiff it will be a tad unstable at brace. Builds like this are fun because the pucker factor is high!

[Bayou Ben]

Great advice so far.  I don't have much to add there, but when I find myself with a bow like this, where there's an uneven amount of reflex in one spot over the other, I rely heavily on tillering with slow motion video clips.  I'll watch the video many times before I remove wood.  I'll take a mental snapshot of the part of the limb I'm wondering about, let's say 6" of the midlimb, and I'll follow that part from brace to full draw in slow mo. Then I compare that to other 6" sections and you can get a good idea of how much it's bending regardless of how it "looks". 
Like Brad mentions, if you know your taper is where you want it because you meticulously prepped it, and you are close in weight, let the thing come out like it wants.  Preconceived notions of what these should look like should be thrown out the window IMO.  There's too many variables from the form you used, to the amount of heat you used, the wood, amount of glued in reflex, bow length, etc, etc, etc, etc, etc, etc.....

[Badger]

   Good thread, good input here!

[upstatenybowyer]

Sounds like a book in the making Steve, "The Pucker Factor." 

The video idea makes a ton of sense Ben. I try to do as you described while I'm pulling on the tree, but that doesn't leave a whole lot of time for careful consideration.

I've spent the last 24 hours redesigning my caul, attempting to even out the reflex, put it right where it should be, and making sure each limb is as close to a mirror image of the other as possible. Not sure if you see what I do from the unbraced pic, but the two limbs do not look the same to me. The reflex looks more gradual on the left than on the right.

[Bayou Ben]

The video idea makes a ton of sense Ben. I try to do as you described while I'm pulling on the tree, but that doesn't leave a whole lot of time for careful consideration.

Yeah it's just easier to sit down and only focus on that area of concern and how much it's bending; not having to worry about pulling the rope and blocking out the rest of the bow profile.
I'm often surprised at how much that "stiff" spot at draw is actually bending through the draw cycle.

[DC]

Jeff, do you bend both limbs at the same time? I have a one sided caul that I made so I can bend different length bows. I sometimes bend the limbs one side at a time so that I can overlap the backing. Anyway I find that if I do one limb at a time I have a hard time getting them even. I get way better results(as far as eveness goes) when I use my adjustable caul and do both limbs at the same time. However with the adjustable caul I have a harder time getting more curve toward the tips. My adjustable caul is just a 2x4 with three posts(one fixed in the middle and two movable ones at the tips) and I use clamps to pull the limb down to make the reflex. Oh, all of this is for backed bows. For self RD I use a single limb caul and steam bend.