Chapter 7: the Tiller
Most of the manufacturing time for self bows is devoted to getting the bend just right, the process of tillering. Some bowyers subdivide this further into three stages: floor tillering, longstring tillering, and short string tillering.
The central idea in tillering is to identify which areas of the bow are bending and which ones are stiff. Leave the bending areas alone and carve away the stiff areas, until they bend.
The other main idea is that you never want to pull your bow harder than the intended draw weight. Since I’m making a 40 pound bow I should never push or pull harder than 40 pounds— that will just unnecessarily stress the wood.
Don’t forget to exercise the limbs between tillering sessions. Sometimes you have to work the limbs a bit before the tiller catches up to your adjustments.
I’m starting out with floor tillering. All I’m doing is pressing on the bow with roughly my target draw weight of 40 pounds, while I watch the limbs bend in a mirror. Floor tillering is much faster and less work than longstring tillering, but it’s easier to make a mistake.
After checking each limb, I flip the bow around and check the other. Floor tillering doesn’t show you how the limbs bend in relation to each other, it only reveals the tiller of one individual limb at a time.
Floor tillering isn’t for everyone. If you’re worried you’ll mess it up, it’s ok if you skip it entirely and start with the longstring instead.
Making a Tiller Tree
Here’s a simple way to rig up a tiller tree so you can longstring tiller from a safe distance. This design also doubles as a portable tiller tree that you can either use on the ground, or clamped upright like a normal tree.
You absolutely don’t have to make a tiller tree, you can tiller with a mirror, or just pull by hand. There’s also a popular device called a tillering stick. If you want to make one there are many guides out there. I recommend making a rope and pulley style tree instead— they’re a lot safer and less stressful on the bow.
I mortised in the bow pivot for extra strength but you don’t need to.
You also don’t need to use a beam this massive. Most scrap boards will be fine, as long as your tree doest warp badly when you draw the bow.
A clothesline pulley is surprisingly strong and can even handle warbows. They all have differing mounting methods so you’ll need to think of your own way to rig the pulley to the tree.
I’m using a very tough hickory peg to hold the pulley. Most other woods may not be strong enough while still fitting in the hole.
If you can, angle your pulley mount away from the bow pivot, so the bow doesn’t pull it out.
The pulley can be held by friction but I added a removable screw to be sure it won’t move.
String a cable or rope through the pulley and add a strong carabiner.
Adding a handle makes the tree much more comfortable, but you can also just tie a loop in the end of the rope.
Last thing, a note about draw length. The draw length numbers on my tiller tree assume that the handle is 1.75” thick. Since individual bows may have differently sized handles, the numbers may be shifted off slightly for any bow with a different handle size. Keep this issue in mind if you want to put measurements on your tree. Now we’re almost ready to longstring tiller, we just need a string.