Tiller question on a Yew Longbow (full draw pic)

[Weylin]

I'm tillering out this yew longbow and I'm finding that I'm second guessing myself. It is 66" ntn shooting for 60# @26, the limbs are equal length. The bow has 1 1/8" reflex but most of it is in the bottom limb. The bottom limb has a bit of natural reflex whereas the top limb was pretty much straight. I used some heat to induce some matching reflex in the top limb but most of it has pulled out (this seems to happen a lot with yew). Right now at brace there is a 1/4" difference between the top and bottom limb, the bottom being the stiffer. However the top limb seems a little meatier than the bottom limb, I'm sure that the reason is the difference in natural reflex making the bottom appear stiffer. The OCD in me is saying to take more off the bottom limb to make it appear to be bending as far as the top limb but my intuition tells me that if I do that then the bottom limb would be too weak and would be under more strain than the top even though the tiller "looked" good. So I guess the question is whether the reflex adds to the strength of the limb making it as strong as the top limb with less mass or if it simply means that the limb has to travel farther to get to the same place as the top limb and by reducing it's mass I'm asking for trouble by over-straining it. I hope my ramblings made sense. Am I over thinking this or is it a legitimate question? Also, feel free to give any general tiller opinions as well.

[Zion]

As you continue tillering the reflex might be pulled out of the bottom limb. But i would tiller both limbs farely equally, and if it still seems sketchy to you then just take your time. Also make sure to exercise the limbs ALOT between wood removal. It looks like the limbs have nice flex tho, so doesn't look like you need to worry about hinges etc. i would mostly concentrate on getting it to a reasonable weight

[Josh B]

Follow your intuition.  The braced and fulldraw must reflect any character, reflex, deflex and any and all other eccentricities that your bow is showing unbraced.  The tip travel is the key.  If those are travelling the same distance throughout the draw, you have it right.  The limbs don't know anything about reflex or deflex.  The only thing that matters is how far they are bent from a resting point to fulldraw.  If you tiller the the bottom limb to appear 'symmetrical'  with the top limb, it will  be asked to travel farther than the upper limb.  This will lead to handshock, unnecessary set in the bottom limb and a shortened life span of the bow.  Its looking pretty good right now.  Josh

[steve b.]

I agree with Gun Doc.  I don't think a reflex'd area is stronger, to answer your question. 

I look at tillering any part of any limb as a percentage of movement that that area should move, whether they are straight sections or not.  So if section "3" of some limb should be moving such and such a percent of the total limb movement then that section needs to move that amount, again, whether its already bending in some direction.

One thing I do when tillering, when using the stick, is to measure off the floor to each limb tip at brace.  Then I draw the bow using the stick and take another measurement of the limb tips to see if both are moving the same amount.

sb

[adb]

You're doing fine so far. Don't worry about limb thickness, or mismatching reflex, etc. Only worry about what shape the bow perscribes at whatever draw length you're at, and continue from there, keeping the tiller as even as possible. As you can see, your bottom limb (despite the reflex) is actually bending more than the top, especially at the tips. The limb's thickness will be determined by the tiller. Try not to think on it too much... just keep removing wood where the limbs need to bend more, and carry on! That's shaping up to be a fine bow, and you're well on your way!

[Keenan]

Weylin, Some good input so far. Another option would be to put her back on the caul and induce a little more reflex in the one limb. Looks like you have enough mass to heat retiller and still hit the weight you want.  With yew sometimes a second session of heat treating will hold better.  Nice and slow, deep heat.

[Carson (CMB)]

Weylin, I was just wondering how that bow was coming along, and it looks to be coming along nicely.  I like what Gun Doc said about reflecting the unbraced profile throughout brace, and full draw.  Well said.  And like Keenan said you can try heating reflex into the top limb again.  The only time I have made heat corrections to yew, I used steam heat then clamped it down overnight, then hit it with dry heat in the morning, let cool, and then unclamped in the afternoon.  That method seems to work well with yew. 

[Weylin]

Thank you everyone for you input, it is very appreciated. The more I think about it and the more I read your comments the clearer the answer becomes to me, it's funny what you can talk yourself into in the heat of tillering a bow.

@Zion, thank you for your comment. If I pull the reflex out of that bottom limb that would seem to be a sure sign it is under too much strain and is taking set, I'm hoping to avoid that. I agree that the limbs seem to be bending pretty smoothly without major stiff spots or hinges. the tips are bending a little more than I want right now but I think if I stay away from them for the rest of the tillering process then they will straighten out. As for the limb exercising, there seems to be two camps on that theory. I find it really interesting, and I'm not trying to pick on you at all by bringing it up because I know a lot of people swear by it. The people that I have learned the majority of my bowyering from don't exercise the limbs any more than necessary claiming that it just puts the bow through un-needed stress and adds set. I'm curious what people's thoughts are on this.

@Gun Doc, Thanks, this is really the direction I was leaning it was just hard to convince myself of that last night for some reason. By the way, I'm still really enjoying your prairie rattler bow. It really launches an arrow. I think the sinew might have dried a bit more and added some weight. I measured it the other day at Gordon's house and it pulled about 70# at 26. As long as i keep up with my pushups and pullups I might use that bow to kill a big elk next year! 


@ steve b., Thanks, I'll try the tip measurement method. I've been drawing a perfectly straight line down the side of each limb and then measuring how much the line is bent in each spot along the limb. That has helped me keep things pretty even up til now.

@adb, Thanks for your input. It seems like you are telling something different then Gun Doc and Steve b. maybe I'm misunderstanding you. It seems like you're telling me to ignore the reflex and make the tiller symmetrical. I feel like if I keep removing wood where it seems the limbs need to bend more then I will end up whittling  the bottom limb away to nothing to counteract its reflex leaving in grossly over strained. I'm afraid I've done this to a limited extent already but I still have enough meat on the bow to rectify it. I did notice that the bottom limb seems to be bending further when i start to draw the bow a bit which is strange since that limb appears stiffer at brace. It changes as I draw. I'm not entirely sure how to interpret that.

@Keenan, I think i will try to heat in some more reflex in the top limb to match. That would likely solve a lot of my apparent problems in perception.

[George Tsoukalas]

I would put the reflexed limb on the bottom. Then as you partial draw it in your hand note the evenness of pressure on your bow hand. That will tell you how she feels in the hand and how the limbs are drawing and returning. Jawge

[Weylin]

Well, I went ahead and put some matching reflex in the top limb and did some corrections for string alignment. I'll get it up on the tree today and see how it looks. I'm hoping to tiller it out to full draw this afternoon if everything goes well. I'll try to get some more pictures.

[Weylin]

I got it tillered out to full draw tonight. It is 62# at 26". I need to get that elbow down.    I'll go down to the range and shoot it in tomorrow.







Thanks for looking.

[ionicmuffin]

looks good! i think you will be happy with this one!

[ionicmuffin]

also, how are you feeling about that bottom limb? is it feeling about the same as the top? sometimes the eye isnt as accurate as the feel of the draw. does she draw smooth for you?

[Del the cat]

Looks good.
Del

[steve b.]

That's a monster, and it looks great.  I didn't think to reflex the one limb; that's the way to go.