TILLERING FROM INTENDED DRAW WEIGHT EARLY ON

[Carl Galvin]

I was reading some of the posts and some have suggested that they try to get the bow down to intended draw weight and tiller from there as esrly as possible in the tillering process on a tillering stick, so as to avoid a bow coming in light on the draw weight.  Can someone please elaborate on that, or is that a misinterpretation on my part?  Thanks!

[penderbender]

Yes you always want to pull it to your intended weight. If you want a 50 pound bow, pull it to 50 pounds.  If it's 50 at say 18" then you can take even amounts of wood off and pull again to 50 pounds, it might pull to 19-20 inches now but it will still be at your weight. So you just keep working it like that until your draw length is at what you want. Hope that helps. Cheers- Brendan 

[Del the cat]

I'd just add the caveat...
Always pull to the full target weight UNLESS you can see a problem with the tiller... in which case you trmove wood to improve the tiller and try again.
Del

[willie]

I'd just add the caveat...
Always pull to the full target weight UNLESS you can see a problem with the tiller... in which case you trmove wood to improve the tiller and try again.
Del

to which I might add....
even if your stave is only bending one inch

Actually, if you compare your stave bending to what would be brace height, to a pic of a comparable well tillered design at brace, you can see where you need to make adjustments

[BowEd]

Yes you always want to pull it to your intended weight. If you want a 50 pound bow, pull it to 50 pounds.  If it's 50 at say 18" then you can take even amounts of wood off and pull again to 50 pounds, it might pull to 19-20 inches now but it will still be at your weight. So you just keep working it like that until your draw length is at what you want. Hope that helps. Cheers- Brendan 

Carl....Getting it to bend evenly early on both limbs is always my first intention.Trying not to stress any one portion of the limb more than another.No matter what the draw weight.Hopefully always above your intended draw weight yet.From there taking even amounts off both limbs to your intended draw weight and length.I usually stop short 1"to 2" or so of my draw length at intended draw weight and clean all marks off if that has'nt been done already which should be mostly done by then too.
Many times if later in the day at this stage I lay it down over night to finish up the next day with a fresh outlook on things on the bow.I then can examine completely how the bows profile has taken the torture I've put it through the day before.Some shoot the bow a good 50 times too at that time which is'nt a bad procedure to do either.Study it very well.Take any slightly stiff spots out if any.Sneak up on that last 1" of draw length with a scraper and sand paper slowly.Shoot the bow in.Put the finish on it.

[Badger]

  One thing I like about tillering from the beginning at full draw weight is that all parts of the bow are always too strong. You can't hurt it even if it is way off unless you get a part of the limb to weak.
You just keep making gradual corrections at full draw weight and the bows tiller just keeps improving and you haven't hurt anything because all parts are always too strong.

[Badger]

   I screwed up on one last week. I went back to my old ways of floor tillering till I felt it was ready to brace. It looked good when I braced it but after a couple of pulls a weak spot showed up. That will never happen if you always tiller to full draw weight.

[Springbuck]

 "some have suggested that they try to get the bow down to intended draw weight and tiller from there'

I think I do read a misconception in here.  The idea is not to get the bow DOWN to intended draw weight.  The idea is not to PULL it any harder than final draw weight while you work in the tiller.

Imagine I rough out, say, an ash flatbow:  68" long, 2" wide limbs, side taper starts halfway out the limbs, narrowed handle about 1-1/2'' thick, and I chopped the limbs essentially 1" thick the whole way down.   I want the finished bow to pull 50 lbs at 28".   

 Now, I know from experience that 1" thick limbs are too thick, WAY too thick for a whitewood flatbow.  Might work as a starting point for a narrow yew bow, but not ash with a stiff handle.  At this stage I could place the tips on bricks, stand on the handle, and bounce on the thing.  It's a BEAM, not a bow. It would pull dang near 200 lbs at full draw.  More importantly, if you just forced a string on it at a 6" brace height, even just THAT might break the bow outright. It will certainly take a ton of set and form massive hinges.  If you pulled it, it to full draw, it's going to break.

So, INSTEAD, what I'm gonna do is this.  I'm going to grab one tip and the handle, rest one tip on the floor and give it a little push/pull with my body weight.  It'll likely feel like I'm trying to bend a fir 2x4.  So, I know it is way too stiff.   I'm going to immediately remove some belly wood, so I rasp all the belly surface of both limbs and keep an eye on the thickness, trying to keep it even all along.

After a couple of passes, I try again.  Still too stiff.  Repeat.  I'm approaching, say 3/4" thickness now.  Next time I do the floor tiller thing, I can feel it bend a bit.  THIS is the MOMENT.  Basically, from this point on, I will never pull on the stave or bow with more than 50 lbs.  I put the bow on the tree with the long string, and pull that string down with 50 lbs of force and NO MORE!

The problem is that a lot of guys will at this point want to see the bend, so they pull it harder.  If you do that, esp. on a notched tillering stick, you run the risk of causing the bow to take set.  Not just set, but set at a hinge (because the whole limb is too stiff, but some parts WILL be stiffer than others and the bend will migrate to the weak spots).  If you pull it with 50 lbs and the bow doesn't even move, what have you lost?  It didn't hinge, or even bend much, so, no harm done.

I go back to rasping the belly evenly.   One pass each limb (I mark the whole thing up with a dark crayon, then rasp off all the marks.)  Check it again on the tree, with ONLY 50 lbs of weight.  Eventually, the limbs start to bend, but only one or two inches.  Regardless, you now adjust the tiller.  Say the tips move only one inch, but all the bend is on one side.  So, do one pass with the rasp on the stiffer limb.  Check again.  etc..

Let the weight pull you out to full draw while you tweak the limbs into the correct bend.

[jeffp51]

Carl,

This and your other post about bending at the fades are related.  most bows early on will bend at the fades with the rest of the limb being stiff--this is especially true for beginners and using the method Springbuck describes.  You may want to pull 50#, but if you see all the bend at the fades, then maybe only pull 80% of your draw weight until the midlimbs and tips start to bend. hopefully you will only be a 10 inches or so with a long string (just long enough to reach the knocks).  Once everything is bending mostly even, start pulling to full weight and see how far it draws--hopefully less than 20 inches.  At this point I start shortening my tillering string--first to a one-inch brace and gradually increasing to full brace.  I try to hit full brace 3-4 inches before I hit full draw and do final tweaking from there.

Personally, once I start to get the stave bending just a little, I switch to a card scraper.  More aggressive tools and more experienced bowyers can get closer with floor tillering and a drawknife--some can tiller a bow in an afternoon.  I am not one of them.  It takes me 3-4 weekends to tiller a bow.  But since this is how I relax, I am not in any rush at all.  As a matter of fact, going faster would just mean I run out of wood faster, so slow is more pleasurable for me.

[Badger]

  Jeff, you don't need to go to 80% until they are even. As long as they are still too strong you can pull the full weight from start to finish. If something starts bending too much that will become you new maximum weight. The thing is unless you pull over your max draw you can't hurt the bow unless something starts bending too much which in that case you already screwed up anyway.

[jeffp51]

Badger,  I think I was trying to say the same thing, essentially--or maybe  I am trying to make Del's point of not pulling past a mistake in the bend.  The main idea is to solve small problems early before they become major problems late.  I am usually making small corrections all the way to full draw--and on good bows the problems get more and more minor as weight comes off.  But if you only ever pull to 20 pounds, then you will still see problems to fix and end up with a 20 pound bow.  Getting to full draw weight soon--even at just a few inches is definitely the goal.  Does that make sense?

[Badger]

That does make sense Jeff. Something mysled and almost everyone else I know has struggled with to one degree or another. For most of the past 20 years I have always done 90 % of mine just floor tillering and using a draw knife or rasp. I would get the bow braced and was usually very close to finished. A couple of years ago I started building a lot of heavier bows and I switched to using the tiller tree much earlier in the tiller process. Even though it takes me about 3 times as long to tiller a bow out I am very pleased with the results.

[Springbuck]

  "More aggressive tools and more experienced bowyers can get closer with floor tillering and a drawknife--"

Yeah dat ain't me.  After rough out and preliminary thicknessing, it's a sharp medium rasp, and a scraper.   I feel like I have designs down pretty well, but I still have to sneak up on tiller.

   I went to "leaving my limbs too stiff early and making the fades bend first" because then I KNOW, predictably, what part of the limb will bend first.   I use a weight rather than a spring scale, and the MINUTE that weight moves the tips AT ALL, I can see that it's bending.  Having the rest of the limbs stiff shows it to me, amplifies it.  But, when they do bend, I even em out, clean em up, and back out of that area.

   I work only the rest of the limb from that point on, at least until much later in the draw. As soon as the tips move MORE than the first time, I again know not only that it IS bending, but essentially where.  If I follow this process on out the limb, by the time I have it braced, all I have left  to do is working toward appropriate tiller for the front profile, draw weight reduction, and not screwing it up.

[George Tsoukalas]

I used to tiller that way but do not anymore. It is a good way too start when learning and most bowyers continue with it. Works fine. Jim Hamm was the first to use I believe.

Now, I use a method Jim Fetrow used.

Get the limbs bending well asap. Hit 10# below target weight at 6 inches below draw length. Hit target weight 1- 2 inches below draw length.

My draw length is 26" on a good day.

Less stress on the stave.

Jawge

[Springbuck]

  OK, wait.  Now I am confused.  Everything I was doing was intended, and understood, to reduce stress on the stave.