Author Topic: Limb design  (Read 454 times)

Offline Mckenzie

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Limb design
« on: August 25, 2010, 06:50:00 PM »
I am new to making bows and am currently in the process of making a longbow with a relatively "medium" reflex/deflex design.  I am looking for recommendations on how much curve to build into the press.  Are there any major considerations or is the shape a matter of preference?  I'm not looking for a bow that is exceptionally fast, but I do want it to be pleasant to shoot with a minimum of hand shock.  Thanks in advance . . . M

Online jess stuart

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Re: Limb design
« Reply #1 on: August 25, 2010, 10:42:00 PM »
Is this your first bow?  If so I would suggest you try one of the blueprints from Binghams or Kennym.  Both are proven designs, with recommended stack heights to get the correct draw weight.  Either I think would improve your chances of getting a good shooter the first time.

The amount of curve will have a affect on the bow to much curve can be a bad thing.  It might prove comforting to use a proven design.

Offline Jason Scott

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Re: Limb design
« Reply #2 on: August 26, 2010, 03:04:00 PM »
Hello Mc, I did as you are trying. When I started building I copied an existing profile from a bow I had my hands on. Traced it out on some plywood and made two bows that shot well. The Third bow I thought I would make some improvements in the performance department and failed miserably. I thought I would give those tips some really good reflex so they would add more power and speed. I got too radical. You are wise for not wanting to go down that road yet.

Here's what you can do to make your own new design. Take a sheet of plywood and pop a chalk string line for reference. Mark the center of the line and drive nails at key locations like the center of the back of the riser, riser fade tips, end of limb tips. Then weave a piece of fiber glass around these nails so that it holds the glass in place at these locations. With your finger, nudge the mid limb portion of the glass in the deflex direction until it gives you a nice looking bow profile with smooth curves and trace it. You can move the locations of the nails until you get the profile you want for the bow length you want. Let the glass tell you when you are getting too radical with a bend. Smooth flowing curves is easier, nothing abrupt. Using the center of the back of the riser as a benchmark, giving yourself 1.5” deflex  and .5” to 1” net reflex (2” to 3” gross reflex) to the tips will give you a moderate design with very good shooting qualities. Hand shock can still exist if you get the balance and timing off with any profile.

Offline Robertfishes

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Re: Limb design
« Reply #3 on: August 26, 2010, 05:41:00 PM »
this is a bow I made on a form using Kennys 2009 64" template  

Offline Robertfishes

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Re: Limb design
« Reply #4 on: August 26, 2010, 05:46:00 PM »
strung pic of another bow after tillering and before spray finish. other pic is the form I made from a template I got from KennyM    

Offline Jason Scott

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Re: Limb design
« Reply #5 on: August 27, 2010, 12:23:00 PM »
That's an ideal profile

Offline Mckenzie

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Re: Limb design
« Reply #6 on: September 06, 2010, 03:12:00 PM »
I appreciate your responses.  Both are beautiful bows and I can only hope to design (and build) a similar one.  Robertfishes, what are the small washerlike circles at the middle of each limb (just under the air hose)?  mk

Offline Mckenzie

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Re: Limb design
« Reply #7 on: September 07, 2010, 01:03:00 AM »
I appreciate your responses.  Both are beautiful bows and I can only hope to design (and build) a similar one.  Robertfishes, what are the small washerlike circles at the middle of each limb (just under the air hose)?  mk

Offline T Folts

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Re: Limb design
« Reply #8 on: September 07, 2010, 07:35:00 AM »
Those hold the laminations from sliding side to side when in the form.
US ARMY 1984-1988

Offline Mckenzie

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Re: Limb design
« Reply #9 on: September 10, 2010, 01:16:00 AM »
Makes sense - thanks

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