Working on the lighter weight lever bow showed up some really useful points.
Best to watch this Youtube video first to understand what I'm going on about!
1. Before the string lifts off the levers the bow acts as a short bow with no levers... thus:-
2. The bow, without the levers, needs to be able to be braced and drawn up to the point when you want the string to lift off the levers, This has several benefits.
a) Temporary nock grooves will also come in handy when trying to string the finished bow.
b) The bow is much easier to handle, work on and tiller without the levers.
c) It can be tillered to the desired draw weight and length required at the point string is required to lift off the string bridges.
3. The levers need to have sufficient width to allow string line tracking/adjustment and will probably need guides/bridges to ensure the string is guided correctly onto the levers as the bow is loosed or let down. They also need to be constructed so that they can be shimmed out or rasped to adjust the angle/draw length at which the string lifts.
Note:- they don't need to be very bulky in their finished state, not really any bigger than the tips of a 100# Warbow. The levers on many commercial "horsebows" are ludicrously bulky, mainly because they are made from straight grained timber for reasons of cost!
4. The ratio of lever length to limb length will probably determine the ratio of draw weight per inch once the string has lifted vs when it hasn't.
5. Before proceeding with the heavy bow, I need to have a target draw weight/length for both before and after the string lifts.
You can see in the force draw curve, the string maybe lifts off a bit late? This test bow is too light but if I interpolate the graph to continue without the string lifting off it would probably be 54# @ 28" rather than the 43# @28" which it actually is... Now if we just double those figure, that would give 108# without levers, which I couldn't manage, vs 86# @ 28" with levers which I could ! If the levers lifted a tad earlier, that could come down to a nice manageable 80# @28".
Anyhow, I hope that makes some sort of sense and gives an idea how and why it's a good idea to experiment rather than just diving in and hoping!