Tillering: Thickness or a curve

[policetac]

Hello.
Well, this is my first "real" bow.
I've got two of the same going at once in case something goes horribly wrong!
So far things have gone pretty well.
Currently it's 72" of (I think) Maple on the belly, and Hardware store Oak on the back. (I'm considering Fiberglass on the back just because I have some)
I My limbs are 29 1/2 from the tip to the fades, and I've already gotten pretty far into tillering.
I'm thinking I might be developing some type of a problem here though due to lack of understanding of what's really going on.
It seems as if I'll just get done with fixing one area, and one I fixed just before seems to have become flat again.
I'm not sure what I'm really looking to do here.
I know about the block of wood, and I use it, but that's only helping a little.
So here's my question.
In Tillering, are we looking to "thin" the wood until it bends evenly throughout the limb? Or are we trying to create a "curve" in the limb to achieve some of our characteristics?
Regardless of the answer, could someone please give me a little "experience" based tip that might help me a little? Thanks.
Oh.
I haven't cut a rest yet. I'm wondering if I should or not. If I do though, do I want to go right at the center half of the bow, or an inch or two "up" the limb? (I heard an old timer say it works better for him to be a little "off.")
Also, on that tillering. What happens if I accidentally go all the way to the back? Can the bow be crafted with just "back" on the limbs? (I accidentally got a carving "run" that went down my glue seam.
Anyway...
No pics at the moment, but I'll try and get one out later.
This is also a complete hand tool job.
Soo.... Thanks? 

[Pat B]

If you mention adding FG you probably won't get many replies, at lease not good ones.
 Tillering is getting both limbs to bend evenly and together and to achieve the draw length at the draw weight you desire.
If you think the belly is getting too thin start reducing the width. Remember you will be tillering from the sides so be aware of every little bit of wood you remove.
 I think you need to consider your wood options and the mechanical values of each wood.  As far as wood characteristics go your lay-up is backwards. IMO You would be better off by using the maple for the backing and the oak for the belly.

[echatham]

A good book goes a long way.  I started out asking lots of questions on various forums, and then got around to reading the books.  if i had read the books first, i could have asked much more effective questions.  The Traditional Bowyer's Bible Vol 1 is a great place to start and you can find it for well under $20 used at an online bookstore.  good luck and i hope we get to see some pictures.

[lostarrow]

A smooth  taper , the bending of the bow makes the curve. It's not necessarily an even taper because you have to watch the wood bend and take  it off where you want it to bend more to give you the desired profile at brace and full draw.

 echatham  made a good point.  There  are volumes to learn  ( traditional bowyers bible series are the best I've seen for beginner and the experienced alike) and  once you learn the basics , the rest is practice and experimentation.  Welcome to the addiction! Good luck.
  Dave

[Eric Krewson]

If you are using a tillering gizmo and chasing flat spots this indicates you are readjusting the gizmo for each flat spot instead of setting it once and correcting both limbs at this setting before you increase the draw length and adjust it again.

[policetac]

Wow!
A lot of GREAT replies! Thank you to all who have taken the time.
Okay. I took a few pictures, but I'm not really sure if they show what I need to say. Let's see...  Oh, it's a no on the glass anyway as it'll ruin how good I think this wood is going to look!

I guess I do the pics as attachments. (It appears it only allowed one of the pics)

Okay, I think I have two different bows here. One is a hand felled Yew I am still learning to fine tune for my 11 y/o daughter, and the other is the one of the selfbow's I'm working on now.
I believe there's a pic of each of them on the tiller I built, and I think there's a pretty good shot of the wood on my project bow. (White Oak, Red Oak???) I just don't know the belly wood.

Anyway...
As to the forum post.
..."Remember you will be tillering from the sides." 
Okay. The closest to a definition of tillering I can find would be an old English reference to a crossbow stock, and the "synonym,"  lathe. So I would assume then; Tiller- V-to remove wood from a stock using a lathe. I.e (sides)
I didn't know that part.

About those books??? lol

[Marc St Louis]

Tillering is the art of training the limbs to bend properly by careful removal of wood using appropriate hand tools, scraper, rasp, sandpaper

P.S.  A lathe does not qualify in this case

[echatham]

Sent ya a pm 

[lostarrow]

Check out the build alongs on this site. Should be a huge help.

[policetac]

Okayyyy!

Just got a real world demonstration.

I was out doing a little light pull snap shooting with my daughter, as I told her to hold up for a moment and carefully work into a full draw.

Watching from the side I noticed that her lower limb was taking almost all of the stress. Almost all in one spot too. (Thank God it's a good Yew bow with plenty of room to grow for her.)

After I ran home and came back with my files, I had her hand me her bow. (I had been able to "see" what it was I was looking for this time and knew right where to start filing.)

After quite a bit of work, I started to also see a bit of what was going on with the "sides" too. (The "tillering" is done on those corners aren't they?) I noticed that as I applied work to them, I could correct twisting, bring out a shallow I was trying to create, or blend a longer stretch into the curve it's been trying to become.
After about 15 or 20 minutes, she was shooting with good power, a smooth draw, straight shots, and decent absorption of the string shock.

I'll try and get a picture of her shooting it tomorrow.

As for mine, I now have a lot better idea of exactly what it is I'm doing at this stage. (Now all I have to do is make my custom handle "look" right!)

Anyway, I would like to thank all who posted advice here today. Your help is, and will continue to be appreciated.

So I guess the lesson here is,
..."It's more reading the wood, than it is searching for a particular measurement or shape. That the process takes time. It can take a while before any real progress can be witnessed, causing frustration and a desire to try and "push" the bow into doing what it is you think you want. (I was lucky that today was a day where I wasn't in too much of a hurry.)

The moral?
Don't be afraid to ask questions, take the advice given, share results, slow down, and remember that I am building a piece of art as well as a functioning tool crafted well enough to feed my family should it ever be called to do so.

(Oh, and the "lathe" synonym applies as a language reference to "turning" "shaping" and "cutting" of the stock.)
lathe
noun \ˈlāth\

: a machine in which a piece of wood or metal is held and turned while being shaped by a sharp tool

1.    a shoot that arises from the base of the stem in grasses
2.    a less common name for sapling

Tillering- The act of shaping a sapling with a sharp tool:)

[lostarrow]

Sounds  like you had yourself an epiphany! Once you do a little more research and learn the terminology you'll be away to the races. Start simple and add a little each bow.(I'm sure you'll make more than a few)Don't be ashamed when one breaks(and they will) . Learn from it! Post pics of the broken ones as well, you'll get a lot of forensic evaluation from hundreds of years worth of accumulated experience on here.  Looks like you're off to a good start, though! Congratulations. If you post where you are located you may have a mentor in your back yard that can really smooth out the learning curve for you.

[policetac]

Well, I went ahead and called this one finished last night.

I didn't want to go for the really fine polished wood look because I got in a hurry and just wanted to play with it!

I'll post some more  pics or a video later on of the results, but so far it's shooting really well.

At this point I can only guess at the poundage, but the draw is a perfect 29 1/2" with really good response, more than enough power for targets, good balance, a flat trajectory, and a good feel overall.

I included a pic of it at full draw below.

Well, off to the kitchen for now. Gotta take time to eat every once in a while! 

[mikekeswick]

It appears as though most of your bending is happening in the inner limbs.
Can you post a picture of it drawn again but with the camera square onto you.

[policetac]

 Thank you for the observation.
 
 I just had my daughter take a couple of new pics from the side. All 3 are of the same draw. I also went ahead and included one showing the handle.

 My questions would then be however,
 
Does the fact that it pulls without breaking now, mean that it will "not" break later? I ask not out of laziness, but out of the concern for loss of power.

At this point in the process, wouldn't I lose power from every shaving I do in order to continue tillering properly? Or is that just part of the risk you take as you are experimenting?

I did get a chance to glance at the Bow Bible Vol.1, but there's a LOT of information in there! Shoot, I'm still learning the terminology! lol

Anyway, here's those pics.


 and if so,

[lostarrow]

Is that your standard draw, or are you afraid to pull it back further. Not saying it's wrong, just a question. That is the sort of draw people use with a native style shortbow .It's legitimate , however on a bow like this you are robbing yourself of some of the potential with a shorter than necessary power stroke. All of that aside you should be proud of yourself for getting a shooter on your first try with no mentor or teacher at your side. There's room for improvement of course , but there always will be.
 
In answer to your question: you will lose draw weight with more tillering ,but it might mean having a bow that shoots  well for a long time vs. having a stronger bow that could break at any time. It's imperative to get the tiller nailed down within the first few  inches of  drawing it back and then simply maintaining it and  as you work it inch by inch to get it to the draw length/weight you want. Tillering it at this stage will help, but the damage may be done  on the weaker areas.

 There are no  guarantees that it won't break at some point. There never is .

 Once again, you can be very pleased with your  first bows! Shoot them ,have fun ,and build more! I look forward to seeing more in the future.