Turkish style bow

[mikkekeswick]

I have finally got around to having a bit of free time to use my new Turkish style form. I'm just going plain on the first one with a laminated flooring boo riser with a micarta I beam. Bamboo again for the limb lams, black glass for the belly and clear for the back.
It's 48 inch nock to nock, I'm gluing it up at 1 1/2 width but where I am stuck is the taper rate and lam thickness......
I've made a few Turkish hornbows so know the taper rate they need to bend correctly and what thickness gives you what but how to translate those figures to a glass bow? Well i'm not experienced enough to do that yet!
I'll take a picture of the finished form and some measurements and post them here this afternoon.
Has anybody out there made something similar and would care to share tapers, thicknesses etc?
Any ideas at all are welcome!

[fujimo]

chat to kenh- he made a scythian bow a little while ago!

[fujimo]

you gotta keep us up to full speed on this one Mike- we all love these asian bows- thats gotta be next on my list- just in two minds whether to go with a scythian, or a mygar/hun

[KenH]

Hi Mike;

I know my Scythian is radically different with all it's reflex and deflex, but it's the same 48".
     

It's 1.5" wide as well, with the taper startin at midlimb.  The total stack height here, to get my desired 35# @28" is .020" with an added .07" "riser".  That's .03 glass back lam, 2x .07 full length wood lams, 2x .07 'riser' lams faired into the center of the set-back handle area, and a .03 glass belly lam.

My best advice is to make a prototype as cheaply as you can.  Then use the Lam Stack Calculator to derive the correct stack for the draw weight you want and make "your bow".

Cut a couple very thin wood lams from 'deal' wood and use two cheap black 'glass lams.

Looking forward to seeing what you come up with!

[fujimo]

funny how sometimes the obvious is right there in our faces-
thats some of the best glass building advice  around-
2 pieces of black 030 glass- total 18 buck- some glue and cheap wood- and prototype is born. i wish i had done that. all the effort i put into a bow that is way off weight- all the fairing and feathering and shaping... and i cant just put it down- i have to finish it, cos there is some $ invested in it. if it were a cheap bow- i wouldnt have worried that much about glue lines etc- just get it together-
good advice Ken.  

[fujimo]

think you mean total stack .200 though ken- just a typo!

[mikkekeswick]

Sorry for the delay with pictures...things always get in the way!! Bear with me on this one.
Thanks for the advice. Ken why do you use deal? Doesn't it's lack of stiffness affect the draw weight? I ask because I have made the exact same bow with the exact same stack height one with black walnut cores and one with ekki/black palm. The ekki/palm bow came in at 6# heavier.

[fujimo]

mike- the way i read it, and i may be wrong- but i think what he means by "deal wood" is bargain wood- not the specie "deal". maybe just some very unattractive/plain lams, in the kind of wood you want??!!        

i do know that when i use yew lams in a bow- i need to add 10% to the stack- to hit target weight.

yea Mike... lets see some pics good man- i am about besides myself in anticipation   :D

[KenH]

Fujimo -- what's a decimal point among friends, eh?

Mike -- Why deal?  
1.  It's C.H.E.A.P.
2. Prototype draw weight is irrelevant.  You're using it as a baseline, so you can calculate the stack for the bow you want.
3. The wood between lams only supplies 12% of the "power" of a bow.  The fiberglass is 88%

"Deal" for us in the States is generic Pine.

Only finish out the Prototype enough to get rough limb tapers and shape; so you can put it on a tillering te and get its draw weight.

[fujimo]

no problem mate    

there you go then- i was incorrect mike. he WAS talking about Deal- sorry for meddling- when i should have been listening...      

still the best advice for a prototype bow!!!

[mikkekeswick]

Deal is a generic pine here too. It's also called 'redwood' here as well. I have a whole heap of ash that will be perfect for prototypes, I also got some bamboo flooring that at first appearance  looks perfect. I will be using that throughout the whole bow, riser and limbs.
Yes I see what you mean about just getting one together Ken.
Fujimo - sorry for the delay!! Yesterday I managed to source a proper 3 phase industrial extractor fan for my new spray booth. I had to go and pick it up before somebody else bought it otherwise I would have got this bow glued up....
Today is going to be trying to fit the fan and wiring it for single phase supply.....the bows will have to wait until tomorrow! So i'm afraid you'll have to wait a bit longer Fujimo    Rest assured tho i'll be on it as soon as possible this is the bow I want to shoot. Maybe i'll get the kasan's glued up today.

[fujimo]

how are you going to wire for single phase?
i have to wire some 3 phase motors for single right now- when in the old country- same power configuration as the uk- my brother wired about 8 or 10 machines in our factory that were 3 phase- for single- he just used a capacitor on each motor- and some star/delta conversion.
to do these new machines i have been advised to build a rotary phase converter-
what are you doing???

[mikkekeswick]

Wiring it in star with an 8 mF capacitor. I've done that but found out my whole workshop was wired by a complete numbskull....the whole workshop is running on a fuse spur from a socket ring in the house.....SERIOUSLY!! So today i'll be putting in a fresh circuit direct from the main board in the house.....why is nothing ever simple!!!
All I want to do is make a bow!

[KenH]

Cheop's Law in action:  Nothing ever gets built on time or under budget....

[mikkekeswick]

Well I finally got one glued up .....but it's well over 100#...umm.
I'll go through my recipe book and get the stack height numbers I used on it. Post them here and maybe get some ideas what thickness I should try on the next one. Ideally I want a nice light one around 40# or so to learn how to shoot with a thumb ring.

[KenH]

Did I not send you the Stack Height Calculator?  send me a regular email: kenhulme at gmail dot com

Now that you've got a prototype -- even at 100# -- you can calculate the total stack thickness for the draw weight you want.

[mikkekeswick]

Thanks for that Ken. I'll send you an email straight away.
It's bending as it should anyway which was my main concern. I'll try and get a string on it today for a laugh.

[fujimo]

got any pics Mike- even if its only half finished- just to see the shape- i can hardly sit here- so excited- wanna see some pics!!!!!   :D

[mikkekeswick]

I had a go at getting a string on but....I got halfway down my stringing board for bows like this and I physically couldn't bend it any further....I can't believe how stiff this thing is. You'd have to be a beast to shoot this bow! I've a feeling it's a wall hanger.
The total stack was 0.327 at the butt ends with an 0.004 taper.
Fujimo - I'll stick my camera on charge before I go out for a run.  

[fujimo]

awesome- cant wait!