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    DURAL ALLOY PROD BLANK--RECURVE DESIGN

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    WINCAR
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    DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by WINCAR on Wed Jan 11, 2017 7:26 am

    Hi ---maybe futile ---but ------
    If anyone can post the design /shaping plan configuration

    for a 30 inch long 2 inch wide dural prod blank ?

    Have made several back in the 70 /s --fed up with heavy steel spring
    prods -----
    so I imported a dural blank recently

    but have forgotten/lost original template- mostly how its shaped /cut down  RECURVED at ends --ie how much to bend each tip curve etc

    would appreciate a sketch or foto of the shaping process or similar
    dural is light --great for hunting in mountainous African bush

    Spring steel prods are a nightmare to carry after several km
    great power but WAY too heavy ---

    dural has its fatigue drawbacks etc etc --but still love the old recurve
     any help would be wonderful
    ( retired pro -hunter /taxidermist )
    WINCAR  -Zululand

    c sitas
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by c sitas on Wed Jan 11, 2017 8:37 am

    Hello Wincar, welcome and good to hear from you. I'm not famliar with the dural you mention. There are several places you can buy  "fiber glass recurves for crossbows. A lot of the fellows hear make a loose laminate glass bow. They are super light ,non recurve, and max out around 200 pds. I have such an animal and cock it with a home made goats foot. I hunt deer with it also. Not true to any of the old type crossbows ,but deadly just the same. Keep checking here cause we have almost 2000 thousand members, maybe some will know exactly what you want.

    WINCAR
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by WINCAR on Wed Jan 11, 2017 11:19 am

    Thankyou  C Sitas ----

    Dural k or  Noral ----is a aircraft grade aluminium /steel alloy --
    used in aeronautics --
    was very popular for x bow recurves in the past --not used much as I find it extremely
    hard to locate a supplier --but eventually found one --recently

    I could probably hazard a guess at the recurve radius ----that's how I made many leaf spring
    heavy steel prods ---all very powerful --20 yrs old some --hardly fatigued --but oh so heavy /the recoil /shock is very audible on 200 lb draw release ---frightens everything away ----not good for hunting --obviously -

    Dural allow is super lightweight----silent --like glass prods --
    as I have not the technology to laminate fibre /resin prods --its simpler to bend /shape /polish
    aircraft alloy --
    but will wait until someone has the template /bending dimensions for  -although its highly unlikely
    these days ---compounds rule!

    regards -----Wincar --

    c sitas
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by c sitas on Wed Jan 11, 2017 11:40 am

    Hello Win, I think you might have misunderstood what I meant about a loose laminate bow. You don't glue anything. All the pieces just lay against each other. Very quiet setup. Very low tech. I really like your explaination. It instantly brought back some memories. Many years back I owned an aluminum bow . About a six footer. It was as I remember, fairly quiet. Only thing was you could feel it resonating in your hand ,after a shot. It never broke either.You sound like a rather accomplished metal person.

    Andy.
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by Andy. on Wed Jan 11, 2017 2:04 pm

    Hi Wincar, good to have you here!

    I've been looking for Dural too, though most alli alloy suppliers don't know what this is.

    Where did you locate your blank?

    Thanks

    c sitas
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by c sitas on Wed Jan 11, 2017 4:50 pm

    Hey guys, Just looking around some,it seems some of the high end bikes use the tube for their frame work.As long as it's still made, someone should be able to locate something.

    WINCAR
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by WINCAR on Thu Jan 12, 2017 3:18 am

    Hi Andy --- after a long long 7 year search

    got hold of a friend of a friend ===of another friend -
     until finally ---Maryellen ----
    gave me the email of
    DARKWOOD ARMOURY !( no idea what part of planet earth they are on --

    BUT  a super fella by the name of Scott ---
    tells me he has all sizes /of aircraft DURAL  alloy blanks ---up to 29 inches
    long --2 inches wide -----
    he CUSTOM  builds alloy prods as well !
    will build to your specs /desired size ---
    (Google Darkwood ARMOURY or armory ---)
    will try post his email
    This has taken me 40 yrs since I recurved /shaped a 120 lb draw prod --
    from a blank Aircraft alloy --
    Yes --very hard to find this old school prod material --
    but I hunted 12 yrs ------with this light as fibreglass prod ==rugged --reliable
    but they do tend to fatigue ---some shatter --simply bind with thin leather or Mc Gyver tape -
    or camo tape if u are hunting --can be recurved over & over when metal fatigue lowers draw weight -
    or replace ----but cost nowadays can be a problem ---
    Dural is tricky to bend /cut/recurve to specific angles----- but not rocket science---made many mistakes back in the 70 but careful measurement /graph paper or a template from DG QUICK  in Gloucestershire --
    (Did the trick -although those templates are hens teeth nowadays )fine 32 teeth hacksaw --blade --do not grind or use angle grinder ---heat will affect the temper of the alloy ---use elbow grease & patience!!

    good luck ---

    Andy.
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by Andy. on Thu Jan 12, 2017 4:47 am

    That is great info Wincar!..... very much appreciated!

    As you probably know, the first Barnett prods were Duraluminium as were those of the Whamo and little Jayhawk. The later Crisbow crossbows from Sth Africa had alloy limbs too, and managed to survive quite acute flexing and were rated at 150lb.

    If taping or strapping precautions are taken, then I agree, Dural is a very useful and safe material indeed!

    Good info on cutting... thanks. How do you recommend bending/forming recurve tips into this alloy?
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by Geezer on Thu Jan 12, 2017 9:53 am

    Geezer here: Okay, here's some of the straight skinny on Dural prods.  I started making lite crossbows (50-75 lb at 7-8 inches of power stroke) Starting with Jayhawk aluminum alloy prods that were approx 28 inches long, 1.75 inches wide at center and @ 3/4 inch wide at the ends. 190 thousandths thickness (approx 3/16 in.) made prods capable up to about 75 lb with lock 11 inches from belly of the prod.  I once got some 'experimental' prods from Jayhawk that were 1/4 in. thickness.  The additional 1/16 in. thickness Doubled the power.  Yes, spring rate usually varies by the cube of the thickness, but only direcltly with the width.  So double the width and get double the power (less losses for air resistance and extra weight) but add only slightly to the thickness and the power goes up exponentially (but a thicker prod is actually being stressed more, so the limits for draw length should be reduced a bit)  Anyhow Jayhawk told me they were using 70-75 T6 aluminum alloy.  That's what I used when Jayhawk (Oklahoma) sold the business.  For @ 10 years I made my own aluminum prods, while Alchem and later Slobows started making steel prods based on the old Jayhawk asymmetric shaped prods (Jayhawk's prods were 28.8 inches cut as blanks because that minimized the losses from a 12 by 4 foot sheet... cut into 10, 24 X 28.8 inch sections for easy handling when cutting.  That's why everybody builds 28 inch prods.
    Anyway about 15 years ago, Darkwood Armory took over making my aluminum prods.  Now I buy exclusively from them in aluminum as well as some steel prods @ 150 lb. But I still buy most of my steel prods from Slobows, because they offer a variety of prods in various weights. 
    For you guys out there with old WhamO Powermasters, it is possible to refit those with 31 inch steel prods.  Alchem and Slobows used to offer those, and no doubt my friends at Darkwood would do much the same for a reasonable price.
    If you're determined to make your own alloy prods, it can be done on a standard bandsaw, with metal cutting blade.  Just go slow and lubricate a lot.  Then file/sand the cut edges smooth... particulary the nocked ends. It doesn't hurt to stress relive (bevel) the edges as well. You can use the cut prod flat, but I actually have a simple wooden cam bender to put a bit of recurve in the ends... bending the ends won't hurt the temper, but you can only do it once. If you straighten, rebend, straighten, rebend, eventually the alloy will work harden and break.
    Afraid of breaking an alloy prod?  It does happen after long periods of use/abuse.  Just wrap the prod with thin (goatskin is good) rawhide: dye or paint it pretty.  Now you're in no danger.
    Enjoy!  Geezer.

    Andy.
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    Re: DURAL ALLOY PROD BLANK--RECURVE DESIGN

    Post by Andy. on Thu Jan 12, 2017 2:06 pm

    Thanks Geezer!

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