Help figuring out lams for Mongolian style bow

[kiltedcelt]

Okay, so here is my form



and this is the type of bow I'm trying to make (scroll most of the way down the page until you see the Mongol bow - Lukas calls his bow "Genghis")

http://www.salukibow.com/15.html

Anyway, the form is 1 1/2" wide and depending on how big I want those static tips to be it can yield a bow up to 72" overall length, but would most likely be used to make something closer to 60" or less. I've made a few experimental bows using a form of similar dimensions. Up until now those experiments have been failures either because of the form shape or due to materials not being appropriate. So, I bought some lams and glass from Old Master Crafters (he's near to where I live so I can drive up to pick up my lams). What I got was the same thickness lams and different thicknesses of glass. The idea was to make two identical bows that would be about 10# different in weight due to the glass. The lam thicknesses are: .080 and the glass thicknesses are: .050 and .040. The lams are hard maple in case it makes any difference. The bows will have 14" riser sections about 1 1/4" deep from back to belly. I haven't decided yet whether the static tips (siyahs) will be integrated in between the glass and lams (like Saluki bows) or whether they'll be attached outside the glass and fastened on with epoxy and hemp twine reinforcement (similar to Grozer or Kassai bows). So, I'm trying to figure out what the draw weight is going to be on these bows. The only thing I've seen to go off of is the Bingham's charts but they're for bows that are 1 3/4" or 2" in width and I don't know how those projections for draw weight would apply to my design and dimensions. I've got two sets of the .080 lams for each bow, however I could easily get additional lams for these bows if necessary. I'm wanting to get a bow around 30# and one around 40#. So, any suggestions or calculations?

[carver]

i can't wait to see what you come up with...you want suggestions?  i suggest you get started

[Pat B]

Contact James Parker(Huntworthy Productions, a TG sponsor)for info about these bows. James worked with Lukas for a while a few years ago. James is a very talented bowyer with anything from selfbows to the most complicated composite bow designs, both with glass or natural materials.

[Jesse Peltan]

A mongol style bow has attached static tips.  They also don't have deflex in the limbs.  Here's a link to a video of an actual Mongolian bow  http://www.youtube.com/watch?v=UgEp4ZAPbs0   As for the thickness of the lams, it's different for every form so you have to try one before you can make a formula.

[kiltedcelt]

Jesse,

You might be confused looking at my form. It seems like a lot of guys make forms so the bow sits in back facing up. Mine is the other way around - the back is down on my form, belly up. There's pretty much no deflex in the limbs as a bow would come off of my form or if there is it's negligible. I basically patterned this form after the unstrung profile of Lukas Novotny's Genghis bow.

[Jesse Peltan]

I know which way the form goes.  The deflex is where after the riser the limbs deflex until your statics.  You actually want the limbs to come off the riser and continue at that angle, meaning there should be no bend at the ends of the riser.  You don't want to have a set back riser and deflex in the limbs because it defeats the benefits of each and you get the drawbacks of both.

[sw]

I have a form that is a variant to the saluki bow with the short riser and static wood tips. Mine the tips sweep forward when the bow is unstrung and bend back giving it amazing early on draw weight. The lam's for it were a PAIN to figure out the formula for draw weight. I use 1-3/4" lams and glass and grind to a true 1-1/2 at full width. Keeps from any error in sliding around and gives me the ability to make the bow 1-3/4 wide if i need to up weight a touch for the same lam set.

Its still in the testing stages and we will end up calling the bow the Sidewinder "venom". The testing bow is 58" with bows down to 52" being tested. I'm not ready to release it yet but i will see if i can get around to posting pic's of it soon.

Keep up on the project - i am here to tell ya the bow when done right is AMAZINGLY fast and smooth out to 33" of draw due to the way the tips are and the ability to keep string angles way down at full draw.

Dave