Basic tillering / weight question...

[osage outlaw]

I tiller like Del the Cat does. 

Make sure everything looks even with the long string and then shorten it as I go.  I pull until I hit target weight and then keep removing wood until I reach full draw while still at target weight.  I think this is called no set tillering in one of the bow building books, but I could be wrong.

[Lee Slikkers]

It is amazing that you can sometimes overlook or convince yourself everything looks splendid on your bow and then when someone points out the obvious (Thank you Mullet) it jumps out like a sore thumb.  Gonna clean up a little bit in that area and remove a touch from each of the tips and then see where she settles in...

It is super cool the amount of time you folks give to others by sharing your wisdom and experience with those of us hungry folks who come asking on a daily basis.  This IS a different site and one I am very glad to have stumbled upon.

Thanks gents~

[willie]

I brought this thread up from the dead because of it being related to a current thread. I had to do a little digging to find out what the "Jim Fetrow" method was that George mentioned. I am not trying to promote one method over another or wish to start a "whose way is better" discussion. Preventing overstrains of the wood during the tiller process seems to be the stated goal of each method profiled.

How can the guy that is new to tillering best prevent that from happening?

[Badger]

    I made some radical changes in my tillering process over the last few years. Mainly because I have been building a lot of weights and designs that I am not as familiar with. One thing that is glaringly obvious but for some reason I didn't see it for about 18 years is that I can't hurt a bow not matter how far out of tiller it is as long as all parts of the limb are too strong. I used to spend great care floor tillering until the limbs were very even, very often I would brace a bow up and it would be just a few scrapes away from being finished. Too close for comfort. Now I floor tiller just to the point I get a slight flex in the limbs and then go to the tree. Every trip to the tree I am pulling all the way to full target weight and all I do is start the process of evening up the limbs. At all times during the process all parts of both limbs are too strong so I can't hurt anything as long as I don't pull past target weight. Now as I close in on the final tiller, usually starting at about 24" I have to be a lot more careful as parts of the limb will start coming into their final bend and I will no longer be removing wood from the entire limbs.

    The main difference I discovered in doing it this way is that a bow pulled to 40# has some chance of collapsing the fibers if pulled to 50#. Always working at target weight eliminates and chance of surprises. Another thing is that has really pissed me off on bows is that occasionally I will tiller a little too far at the lighter weight only to find out one limb or both limbs have areas that are bending too much and I am forced to tiller the entire bow to match those areas when it is not the tiller shape I had set out to accomplish. It also works very well with the no set tillering technique.

[willie]

It also works very well with the no set tillering technique.

I recall giving the "no set" method a go a few years back. It worked well once I had two things under control.
 
The first being what seemed at the time to be a catch-22 for learning how to tiller. As with all methods,  advice is given to "not pull any further than needed" before taking corrective action. An eye for good tiller comes with experience, and I had to learn what that was before learning any tillering method.
Perhaps others might suggest ways for a new guy to develop an "eye" for good tiller? I had to start with simple bows and simple arcs.

The second challenge I faced before learning how to tiller was the selection of reasonable weight goals, and how to make adjustments when necessary. Springbuck mentioned this in the nearby thread. Monitoring set is a skill of it's own. I would be interested in how other have gotten past this hurdle when first learning. For me it was using the aforementioned "no set" method.

[Springbuck]

   "One thing that is glaringly obvious but for some reason I didn't see it for about 18 years is that I can't hurt a bow not matter how far out of tiller it is as long as all parts of the limb are too strong."

    "At all times during the process all parts of both limbs are too strong so I can't hurt anything as long as I don't pull past target weight."

    This is what I had understood to be correct.  When I started doing it the way I have described in the other thread, three things happened:

 One, I now finish almost all the bows I start.  If I can get it roughed out, dried, and straightened, it's going to be a bow.   Heat straightening and tempering is now where I lose the most staves.  It used to be tillering.

  Two, the bows I make seem to take less set and I'm happier with the tiller.  I can't count the number of times I resorted to changing the front profile and weakening the opposite limb to accommodate a non-fatal hinge off one fade, or something like that.

  Three: My bows now hit weight, at least within a few lbs.  The first 20 bows I made all survived to be shot, but every one was between 25 and 35 lbs by the time I had figured out the tiller.  And they all took a lot of set.

 

[Springbuck]

"Perhaps others might suggest ways for a new guy to develop an "eye" for good tiller? I had to start with simple bows and simple arcs."

I honestly think THIS is the hardest part, and that is a GOOD, maybe the BEST place to start.  I started on Bamboo backed R/D bows.  DUMB, DUMB, DUMB!....

 Seeing what you are trying to see is one thing I can't explain a good method for.  Again, I vote for consistent thickness as a baseline, and endorse use of the tillering gizmo!   I have spent hundreds of hours sketching bows during boring surgical cases, though.   I draw a front profile, then draw the side profile to match, or vice-versa.   I draw a row of limbs, each with a longer recurve than the last to see what HAS to happen to the curve, etc...

I never have actually tried to apply the "no-set' tillering method in an organized manner, but I have tried to understand the principles and keep them in mind.   As a beginner, anything you can do to make things predictable helps.

  For a while I thought of all styles as variations on the pyramid.  If the sides are parallel, the thickness HAS to taper.  If the thickness tapers that section HAS to have elliptical curve, aka, bend less where it is thick.   If the sides taper, no thickness taper needed.

[BowEd]

I agree with ones who say not to figure outcome of draw weight by a guideline weight gain per inch by reducing weight to expected numbers at an early time while tillering.I've calculated those weight gains per inch many many times too and it's tempting to do but foolish really.It's cutting things too fine if any trouble arises.It also takes away any chance a person has to evaluate the condition of the wood as you tiller also.
Although it is nice to know at an early time while tillering that your gonna make the weight that you want.

[willie]

I've calculated those weight gains per inch many many times too and it's tempting to do but foolish really.It's cutting things too fine

I agree that trying to project with too much accuracy is futile. I do like to take a very close look at the bow when I reach brace height with the longstring. Having the bends even and smooth is one thing, having it bend the way it should is another. I will often have a pic of a similar design braced bow for comparison nearby. If the bend shape needs adjusting, I will use less than full weight to bend the bow to the brace height that I am using to make the comparison with the picture. I like to reduce wood until the bow pulls (with full weight) to at least 20" on the long string before actually going to a low brace for the first time.

I wish to encourage folks who are just starting out, to provide feedback about your travels along the learning curve. Sometimes those who offer advice have forgotten some of the challenges they first faced.

[Badger]

It also works very well with the no set tillering technique.

I recall giving the "no set" method a go a few years back. It worked well once I had two things under control.
 
The first being what seemed at the time to be a catch-22 for learning how to tiller. As with all methods,  advice is given to "not pull any further than needed" before taking corrective action. An eye for good tiller comes with experience, and I had to learn what that was before learning any tillering method.
Perhaps others might suggest ways for a new guy to develop an "eye" for good tiller? I had to start with simple bows and simple arcs.

The second challenge I faced before learning how to tiller was the selection of reasonable weight goals, and how to make adjustments when necessary. Springbuck mentioned this in the nearby thread. Monitoring set is a skill of it's own. I would be interested in how other have gotten past this hurdle when first learning. For me it was using the aforementioned "no set" method.

   Willie, I have never had a great eye for tiller. I think that's why I find the method of keeping the limbs strong so much easier. I just keep making micro corrections instead of getting one part looking good and them letting everything else balance around it. I usually bring mine out to 23 or 24 on the long string before I brace. It reads the same braced as it does on the long string.

[BowEd]

The main thing I see of an important concern here is that the whole tillering process is slowed down and that's always a good thing.It's impressive to floor tiller and to brace a bow in quick fashion to impress and may work out great too but to try to get the absolute best out of a piece of wood slowing down always gets the best results I would say every time.