Exercising bow while tillering

[sssnap]

Ok, exercising your bow between wood removal sessions helps prevent excess set. Personally I don't like to partially drawing the bow by hand as I'm never sure that I'm not over drawing by accident. So, I've been using my tiller tree to exercise. My question is what do you consider adequate strain to put the bow thru it's paces and still not over draw it at what ever weight it is at, at the time?
I have a scale on my tiller tree so I know I'm not overstraining the bow. All I've ever read has said exercise and not much more, just want to know what you guys think.

[drewsbow]

what I was told was not to go above your target weight ? I am no expert however so I don't know for sure but sounds reasonable . Drew

[Butch Speer]

Ron,
Jim Hamm said to never draw a bow past the target weight when tillering. Tiller it as usual, then exercise it on your tree, never going past your weight. I will exercise it to weight 15 to 20 times. It can sure change tiller between the 1st. & 20th pull. If you do it like this, then you should never have much problem hitting the weight you want. Plus a lot less set doing this way too. It never over stretches the wood.

[Pat B]

Your tiller tree is the way to go. I start out pulling with only an inch or two of tip movement then a little farther and as long as things look OK a little farther. I do this 10 to 20 times to each point. I will check the draw length to about 5# under draw weight and work my way out to there...SLOWLY!
   By doing so the wood removal registers so you get fewer surprises as you tiller. It is the surprises that cause set because you have over stressed the wood thinking it doesn't bend enough.

[Stiks-n-Strings]

I just got thru reading the chapterin the Bowyers Bible Vol 1 and it is exactly like Butch and Drew are saying. Never go past the target weight.
 This explains to me why I cracked the limb on one of my earlier attempts at a selfbow.
 
 I got me a sweet one I'm working on now and I have been doing alot more reading and alot more taking advice and most importantly slowing it down and taking alot more time.
 Check out the post "And here we go (first selfbow) I am working on it now and posting my progress as I go and soaking in all the input I can get.

[clintopher]

Not only should you not go past target weight, you should stop drawing when you see problems with tiller.  In other words, if your target weight is 50 lbs and at 40 lbs you can see a problem with the tiller don't keep drawing to 50 lbs.

[George Tsoukalas]

I exercise at partial draw 20-30 times ( around 15 inches or so) usually (but no always) wile it is on the tree. I usually unstring to remove wood but sometimes work in the fade area with the stave strung. In that case I exercise the stave by hand. Jawge

[George Tsoukalas]

More on my site. Jawge
 http://georgeandjoni.home.comcast.net/~georgeandjoni/

[Diamondback59]

I DO EM PRETTY MUCH AS PAT AND JEWAGE  DO  BUT   WHEN IM AT MY VERY LAST  INCH AS IM TILLIERING I ALWAYS TRY TO LEAVE 5 - 7  LBS EXTRA  ON  MINE   MY REASONING IS AFTER IT S SHOT IN  AND FINAL SANDING ETC  I USALLY LOOSE A BIT AND IM RIGHT AT OR REAL CLOSE TO TARGET I THINK THE EXERCISING   IS  THE MOST IMPORTANT  STEP IN THERE  CUZ  YOU DEFINATLY  MUST TEACH UR WOOD  HOW  TO BEND AND  IT  WILL  BULID A MEMORY  OF HOW IT S SUPPOSED TO BEND BY EXERCISING   BROCK

[DCM]

Can someone cite a source for the idea "exercising" reduces induced set?

I get the idea it's one way to avoid missing desired weight.  But in my experience exercising a bow prematurely (which if you aren't finished with the tiller is, by defininition, prematurely) actually leads to MORE set.  My thinking, to reconcile my experience, is that when the tiller is not yet perfect you aren't actually working all of the limb(s).  Rather only the parts that are bending are getting worked, in fact worked harder than the surrounding, more stiff wood.  

I try to draw a bow as few times a possible during the trial/error stage of tillering.  Then once I get the limbs working together, sharing all the load, I sweat the bow and fine tune shape and tiller to final weight and draw lenght.  I usually don't loose any weight to 20", then loose between 5# and 10# depending upon the project as I work it up to 28" or whatever.  Similarly, I don't see any set until 20" of draw, and then see 1/2" to 1 1/2" of set in the last stage of tiller and workout.

[Art B]

David has it right. You don't want to exercise anything until you have every inch of the limb carrying it's share of the load.

If you're scraping a spot here or there and then exercising the limb then that only means somewhere along the limb's length there's a place that has to carry more of the load. Thus more set! I know, same thing David said, but it's worth repeating.

Spend more time upfront on getting a good taper to begin with. Comstock got it right when he wrote in his book "The Bent Stick", good tapering produces good tillering. Such a simple concept that eludes so many. ART

[George Tsoukalas]

Very interesting. 2 excellent bowyers offering a different viewpoint. My thinking and in my experience when I don't exercise (very short pulls of no more than 12 inches)between wood removal sessions I end up having the wood removal register all at once and I end up playing overcompensating and missing weight. Never pull more than it takes to reveal a problem. It has no bearing on set, however.  In theory though what you are doing sounds good but wood is not homogeneous even in the same bow.  Heterogeneity is more the norm so the taper may appear good it may not be in actuality. To be fair Comstock doesn't advocate waiting until the end to exercise the stave. Frankly, I wouldn't for a moment think of doing that. But to each his own. Jawge

[Art B]

The way I do mine I still have to exercise the bow back to my desired draw length/bow weight George. But not to the extent that some of you do it. I'm not exercising my bow limbs to reveil any weak places because there are none since I have a consistant taper. I may have to retaper the limbs if the bow's profile isn't what I want once braced. Comstock mentioned that in his book also. Other than that I'm free to apply greater strain to the limbs (with an even tiller) then how you and other tiller your bows out. Seems as though both methods work just fine. But for me, once I get my short string on, just having to reduce weight is much quicker and safer (less failed bows) for the final outcome.

Since I spend more time getting my taper right before I ever go to any kind of string or board I only have to achieve even tiller once braced. After that it's pretty much just dropping weight.

Hope I explained things a little better George. ART

[George Tsoukalas]

"I'm not exercising my bow limbs to reveil any weak places because there are none since I have a consistant taper." Neither am I. Art. I exercise with short pulls for the wood removal to register. Tapering is done by eye though. I don't strain the limbs at all. I don't even hit target weight until I'm l 1 inch under my draw length. I don't  string the stave until it's 10-15 # over target weight. I never rush a stave to the short string. LOL.  Gentle bowyering for Jawge. Jawge

[Art B]

Then our methods aren't all that much different George. Although your eyes may be better than mine, LOL! I have to use a tri-square, caliper, feel and the ol' eyeball (with glasses of course) to get my taper. I have the bow's back, sides, nocks, handle and straightening finished before I ever get to the short string. Everything else comes in rather quick after that. Gentle bowyering for Art also. ART

[George Tsoukalas]

Well, I'll heat and straighten if I have to but I prefer not to, Art. For that reason handle and nocks are shaped at the end so I can track the string better.    Jawge

[sssnap]

That's what I want to know

[sssnap]

Sorry, about that guys, my clumsy hands and this laptop don't jive sometimes. Didn't mean to send that last one.
 Now I'm a little confused as I thought that's what I did wrong on my last one. It was B/L, the back was very lumpy but the grain was very straight the design was pyramid. Using calipers I took the limbs down very uniformly, floor tillered it, took off a little more cut in nocks and put on a long string, and all looked fine took off  a little more and shortened the long string, and all looked fine. both limbs bending even, took off a little more and put the string braced at 4" and had a bad hinge in each limb. unstrung the bow but was to late. I thought my mistake was not exercising the stave to show the two hinges.

[Art B]

Ron, was the hinges in the outer third of your limbs?

ART

[DCM]

Where were the hinges?

Shortening the string changes the geometry.  Sometimes a bow will show whip tiller, or in a most extreme case hinged nearer the nocks, when going from a really long string to a short one.

One develops an intuition about how to proceded from stage to stage as you gain experience.

Only other thing I can think of is that I usually increase draw length gradually, say 1" at a time once I get to about 20" (braced say 4").  It's a slow and tedious process with very modest wood removal.  It's easy to induce or introduce a hinge (or two) with just one adjustment (wood removal).  This is particularly true of "very lumpy" wood.