BBO Tiller Advice

[Steve Kendrot]

Howdy Folks,

Love the centralized bowyers forum. SHould make it easier to track threads we can all learn from. Thanks Terry!

So I am in the process of shooting in my third BBO that has made it to the tillering stage. First attempt was a 20 pounder. Second attempt broke due to a poor glue job and now I am working on waht I hope will be my hunting bow for this season.

It is a Bamboo backed osage with a Bacote stripe in the handle and african blackwood tip overlays. It is a Dean Torges design 64" NTN r/d profile. It is currently drawing 58#@28" and I hope it will settle in at 50-53# by the time I sand and finish.

Here is its unbraced profile:
 

Braced: The top limb (tot he right) looks a bit stiff as braced...
 

Drawn to 55#@27": Top limb still looks a bit stiff, but I have some questions..
 

The top limb looks stiff to me, but the tillering gizmo shows a pretty even bend throughout. I am unsure how to interpret the bend in the bows given the asymetrical limb design of the Torges bow (The top limb is 1.5" longer than the bottom. I tillered using facets as in the Dryad DVD. I've been evaluating balance by the relative position of the limb tips at full draw, but am not sure if this is the right way to look at it given the different length limbs. Do I need to remove more wood off the top limb?

The bow shoots pretty hard. I have never shot a longbow before. This one has a bulbous handle and no cutout shelf so what kind of spine should I be looking for to get that arrow around the riser. Most arrows (spined for my 55# recurve)that I've shot out of it hit consistently 9" left of my point of aim. Will a softer spine bring it right? I really want a bow that will shoot where I look so I can switch between my recurves without recalibrating my mind's eye. Some have suggested I cut a shelf into the handle. Is the necessary?

Your honest feedback would be greatly appreciated.

[Shaun]

I would say yes to taking wood off the right - top limb. Needs a little more bend about 1/3 of the way out from the handle. Caveat - you are going to loose draw weight if you take wood off and you don't have much to give... you can count on 2 to 3 pounds loss from sanding at finish. So you only have 2-4 to give adjusting the tiller. I would go for it and if it gets too light, shorten each tip an inch and end up with a 62", but if you are careful you may not have too.

Yes to softer spine arrow hitting farther right. A self or laminate bow which is not center shot (like your recurve) will need an arrow that flexes around the handle and ends up going where it was pointed. I would suggest 45-50 or 40-45 spine for  a 50# wide handle bow (no cut out).

[**DONOTDELETE**]

what Shaun said. the bow looks nice and a little work on the limb should bring it to bend just right. If you do drop to much weight, do as Shaun said, cut the tips down and retiller to draw & weight. Good luck.

[Steve Kendrot]

OK..I took some more wood off the outer 2/3 of the upper limb. Looks better. I'll shoot it some tomorrow then post some more pictures. Thanks for the feedback.

[wingnut]

Steve,

Looking good!!  Don't get yourself caught up in the "perfect tiller" trap on your first shooter.  It looks great right now and the wieght if good.  Stop and shoot it for awhile.  The next 10 or so will be time for the "perfect tiller" bug to bite.

Mike

[Auzoutdoor]

I would try to adjust your tiller tree so you draw the bow the same as when you shoot it then you will see it will prefer a stiffer top limb anyway.
Cheers KIM

[Shaun]

I like Mike's advice. Shoot it and enjoy it and start another. Tiller is a mystery that becomes more clear with trial and error experience. You did great!

[Steve Kendrot]

I think I am about done. I did take a few more shavings off the limb and it seems a little better.I actually overshot my desired weight a bit so the purpose was twofold. Its currently about 56@28 and I'd like it closer to 50. Its a smooth draw. Exactly 3 lbs/inch from 20 to 28. I am going to throw some arrows through it to get it settled in and then finish it off!

Time to order some more bamboo Mike!

[Chad Sivertsen]

Seeins how this thread is about BBO tiller I have a couple of comments and I guess questions for those more experienced than myself.

On the subject of tiller shapes and unstrung profiles. I've made a few BBOs from glued up blanks and they have a more rounded or circular tiller than Steve's bow in this thread. In comparison his limbs have a nearly straight profile from handle to tip. My bows all shoot fine with the round tiller but would like to hear comments on comparison of tiller shapes.

The unstrung profile of Steve's bow shows it retained most of the backset. The lighter draw bows I've made do the same and the heavier draws are more straight when unstrung. Is this a factor of draw weight, limb shape or a consequence of my amatuer bowyer status. I'm assuming that bamboo to wood ratio is a factor. Comments?

I'm just finishing another BBO from a Dryad blank. It shoots great and I may use it for elk. It is about 60# and the unstrung profile is close to straight. I'm very impressed with BBOs, the smoothness is noticeable and they shoot so quiet! I have no idea what arrow speed is but it shoots accurately.

[Glenn Newell]

I think that the top limb wouldn't look so stiff if the bow was drawn down from where the arrow would be nocked on the string, I would try that before any adjustments were made to the bow. Do you use one of Deans tiller guages to check the bend in the limbs at brace height?...Glenn...

[Steve Kendrot]

I tillered using the Dryad method in Mike and Jason's video. I used the tillering walky-talky as modified by Eric Krewson with the pencil mounted in a hole through the middle of a six inch block.

Chad- by rounded tiller, I presume you mean a gentle arc to the limbs when the bow is braced versus the stiffer appearance of mine when braced? This is only my second BBO, but if I understand what's going on, the reflex deflex design will result in a straighter limb when braced, as the limbs are still in the process of "uncurling" so to speak. This bow has only had about 100 arrows shot through it so it probably hasn't settled in yet also, so it may lose some of its curves.

I created my tillering tree based on Dean Torges "Tillering the organic bow" essay on his website. It has a radiused crown. Balancing the bow on its dynamic fulcrum and placing the pulley hook on the finger location on the string makes for some nerve-racking moments as the bow see-saws back and forth, threatening to skid off the shoulder, until you get some weight evening it out. Not quite sure how to interpret the bend when doing this as the bow does not balance on its dynamic fulcrum until you weight the string. The limb tips never seem to approach the same latitude on my background. Mike does not seem to give a whole lot of attention to this in his video.

[Chad Sivertsen]

Chad- by rounded tiller, I presume you mean a gentle arc to the limbs when the bow is braced versus the stiffer appearance of mine when braced? Yes, that is what I was referring to and your explanation makes sense. The blanks I used had different degrees of backset and that would certainly contribute to final unstrung profile.

Your bow looks good and I'm sure will be fun to hunt with.

[ConnieW]

Chad,

The blanks you have purchased from us are designed to produce the continuous arc profile you are describing.  You can get the straight limb "V" profile by stiffing the limbs tips a bit during glueup.  BTW did I send you a TD sleeve when I sent the blanks?  I think I forgot.

Mike on Connies laptop. . .TDY in AZ

[Chad Sivertsen]

Mike,
That is good cause that is what I ended up with. They almost seem to tiller themselves. I tried to take wood off proportionally, just kept an eye on the arc and focused on weight so this one wouldn't get too light. When I got to about 70# I measured tiller and it was real close so I just used my Bowyers Edge and counted even strokes until the weight was about 60, tiller stayed right on. Just finished final sanding and will post some pics when the finish dries.

I've done a few self and BBOs now and starting to get a "feel" for what I'm doing I think.

I did not get the TD handle or TBB4, been meaning to call you about it and visit a bit too but I have a telephone phobia.

You on your way to IdeeHo?

Steve, don't want to sidetrack your thread. So the profile strung, unstrung, and full draw are determined to a large degree by the glueup form. Thanks makes sense and I likely have figured that out on my own someday.

[DCM]

If you can get someone to take a picture with you drawing the bow by hand, it may better reveal how the bow will be actually used.  Be sure to hold the bow straight up and down, and have the camera positioned exactly perpendicular.  It's sometimes difficult to accurately simulate using a tillering tree.  I generally start shooting a bow at 3" or 4" before final draw lenght for this reason.  If it still looks stiff on the upper limb when drawn by hand, I'd keep an eye on whether the lower limb takes more set from work, even if they both rest back to their starting positions.  Also you haven't mentioned the static tiller measure, which should by rule of thumb be between 1/8" and 1/4".  Finally, how the bow shoots, handshock and cast, is often the best indication of when the tiller is done, within the aforementioned boundries.  Usually I bump along on the last inch or two of draw lenght until I hit a sweet spot in shooting manners, then I just shed weight if I still have weight to give.

Nice job so far.