selfbow layout?

[ozy clint]

ok, i made some firewood today. it was brigalow, so i had good coals in the fire.  
how do you lay out a selfbow? what i mean is, how do you mark out the limbs lengths, handle length, fulcrum and arrow pass?
do you have the top limb longer? do you have the fulcrum or the arrow pass at the center of the NTN. do you measure limbs from the fulcrum, arrow pass or ends of the handle?
today i had the arrow pass at the center of the NTN, the fulcrum was 1 1/2" below that and the handle was centered around the fulcrum. this made the top limb longer.
i use an offset tiller tree. i'm no bowyer but i can't see how tillering with a stick that draws the bow square with the fulcrum can give you correct tiller for how it is actually shot as you pull the string above where the fulcrum is.
that's why you want a longer top limb limb right?

[George Tsoukalas]

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

[Stiks-n-Strings]

Ozy when I lay a bow out I measure to the the entire length and mark center then I mark my arrow pass 1 to 1.5" above center. you are correct this does give you a longer top limb but that's what you want.

 I do recommend you check out George's site lots of good info there as well.

 Good luck and don't forget the pics   :D

[Pat B]

When I set up a selfbow I mark the center of the stave, go out 2" each side of that for the handle and 1 1/2" to 2" outside the handle for the fades. I use a bulbous handle so I grip the handle and place a mark right at the top of my hand for the arrow pass. My limbs are equal length but the arrow pass is about 1" to 1 1/4" above center. My limbs begin somewhere in the fade area. The fade is the transition between the rigid handle and working limb.
  I also agree you should read George's stie.

[Adam Keiper]

I trace the grain from end to end with a pencil for starters.  That will be your left-right reference when laying out the bow's width profile.  If the pencil line runs off the stave to the side or goes through a bad spot, trace a new line for a better layout and erase the old one.

Next, review the stave to see where the best section for a bow lies.  Mark where the string grooves will be, and where the true center of the bow will be.  If you want asym limbs, choose whichever one is cleanest and straightest for the bottom limb.  Make another mark one-half the difference in limb length just below the mark for the mid-point.  (For example, if you want a bow with an upper limb 1.5" longer than the lower, make a mark 3/4" below the mark for the stave's mid-point.)  That mark sets the center of your grip, and is the reference you'll use from here on out.  Erase mark for the true mid-point.  It's no longer needed.

From the center of grip mark, now mark (equally) the ends of the grip and the fades.  The grip will be 4" long (approx width of hand).  The mark for the top of the grip is also the location of the arrow pass (2" above the grip center).  Finally, lay out the bow's entire width profile that you want, relative left-right to your traced grain line, and relative lengthwise to the cross-marks you've made for the grip, fades, and string grooves.

When you start tillering an asym bow on a rope & pulley tillering tree with the grip set more or less firmly in a cradle and the rope clipped on the string from where it will be drawn, you'll see the rope pulls down and towards the bottom limb (if the tiller is right), essentially replicating how the bow is actually drawn by hand.  

Another option is to either balance the center of the grip on a small block of wood or place the grip in a leather sling.  The bow will rock on the block or wood or in the sling when drawn and the rope will pull straight back.  Either way will simulate how the bow will really be drawn.

[steve meyer]

Hi there are several ways to lay out a bow one is to have both limbs the same length the other you have the top limb longer than the bottom. There are advantages to both methods. I usually lay out both limbs the same Length the Way, Pat B does when making flat bows. I usually lay out the top limb longer than the bottom when making English longbows. The main thing to remember is all bows have to have the bottom limb stronger than the top limb so that the top limb bends more than the bottom. The method where you lay out the bow with the taller top limb builds in proper tillering . When you make both limbs the same length you have to tiller the bow so that the bottom limb is stronger than the top. If you make both limbs the same length you can flip the bow at any time during the tillering process. This is an advantage when making character bows.