Author Topic: questions on cast  (Read 380 times)

Offline DVSHUNTER

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questions on cast
« on: July 30, 2009, 11:13:00 AM »
Well, I finally finished my selfbow from mojam.  Beautiful, very little string follow.  Shge is 66 in ntn and 49lbs @ 26in.  My question is what kind of arrow speed should I have with a 10grain per pound arrow.  I've got 130 fps and it seems a little sluggish.  The second bow that I made is a 42@26 and shoots the same 10 grain per pound arrow at 132fps.  Both pieces were dried had rounded bellies.  The lighter bow has a continuous taper to the limbs and the heavy boy has 1 1/2 in limbs and only taper in the last 16in of the limbs.
"There is a natural mystic flowing through the air; if you listen carefully now you will hear." Bob Marley

Offline No-sage

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Re: questions on cast
« Reply #1 on: July 30, 2009, 01:46:00 PM »
A 66" bow for a 26" draw is overbuilt, no matter what the drawweight is, IMO.

Set can be an indicator of several things.  If you have very little or no set when your bow is done, you might have overbuilt your bow.

At 10GPP, you should be able to get 100 FPS plus the draw weight.  In your instance, 149 should be easily attainable.

There are so many variables you can adjust in a bow to get high efficiency.  In your early stages of building, you should be focused on getting good tiller and good shooting manners.  Performance will go up as your level of experience goes up.

Offline Dano

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Re: questions on cast
« Reply #2 on: July 30, 2009, 02:53:00 PM »
I agree with Keith,  Performance will go up as your level of experience goes up. 100 FPS plus the draw weight, is what you should shoot for, but not in your first few bows.
"If the women don't find you handsome, they should at least find you handy" Red Green

Offline Springbuck

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Re: questions on cast
« Reply #3 on: July 30, 2009, 06:54:00 PM »
If I read you right, the above replies are helpful, but whay you really want to know is "why?" you aren't hitting those speeds, right?

  Hard to answer w/o pics, but I agree, at 26" draw, you might be underworking a 66" bow.  That's 30" of working limb on each side of a 6" handle, for rough figures.  There is an old rule of thumb (and it is JUST a rule of thumb) that bow limb length should about equal draw length.  Limbs will cost you cast if they are longer than needed, heavier than needed toward the tips, or if they bend in the wrong places.

  Things that help cast..

  Stiff tips (on most styles).  Stiff tips several inches long are made skinner and thicker, saving a lot of weight, improving full draw string angle, and quelling some of the limb vuibration.

  Toasted belly.  Allows narrower overall limbs at the same draw weight, again, reducing physical weight of the limbs.

  Low set.  Set, esp excessive string follow robs you of good tension on the string at brace, which causes less stored energy (esp. early in the draw) and can add vibration at the tips.

  Reflex, or recurves, add early draw weight.  However if excessive the wood may not "take" the strain and increased set results through the working limb.

  A strong lightweight string.  A heavy, overbuilt string, esp. one like nylon that stretches with the shot kills cast.

  There are a couple more, but if you want to look at your bow and see if you can "tweak" it for more speed go ahead.

  On the other hand, you have two nice successful bows there. Kkeep em and improve on the next ones...
42% of statistics are made up, and the other 62% are inaccurate.

Offline Roy Steele

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Re: questions on cast
« Reply #4 on: July 30, 2009, 07:14:00 PM »
Narrow stiff tips down to 3/8's of an inch the last 4 inchs but light as possable with out been.
  Limbs 1 1/2 to 1 3/8 depending no pounds you want.Tiller as far by into a stiff handle as possable.
  I've bend puting fast flight strings on my bows for probelly 15 years or more.
  Plus I keep my bows in a hot box as it's being built.Keep it as low a temp as possable.This really combats moisture.Helps emimate string follow.Exspecialy in white wood.
DEAD IS DEAD NO MATTER HOW FAST YOUR ARROW GETS THERE
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Offline DVSHUNTER

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Re: questions on cast
« Reply #5 on: August 03, 2009, 05:55:00 PM »
I had the idea that my bow was overbuilt.  It seems quite a bit longer that I wanted.  I want a 60in. for me.  I am having trouble reaching the 55 plus lb. mark that I have set as a goal for myself.  I am wondering if I should cut my limbs down a bit to shorten the length to 62in. ntn and retiller.  I will probably not because It is what it is, but If I did shorten and retiller, would there be negative effects because the bow was already shot in at a different length?
"There is a natural mystic flowing through the air; if you listen carefully now you will hear." Bob Marley

Offline Dano

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Re: questions on cast
« Reply #6 on: August 03, 2009, 07:17:00 PM »
Shorten it, it's a good thing to learn. You'll prolly gain 3-5 lbs. per inch, tiller will change just a bit, take it real slow adjusting here or you'll be back to a light bow if you aren't careful.
"If the women don't find you handsome, they should at least find you handy" Red Green

Offline rainman

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Re: questions on cast
« Reply #7 on: August 03, 2009, 10:03:00 PM »
If this was the bow you were shooting at MOJAM on Sunday morning I think you are getting very good arrow speed.  Your release could be affecting Fps a Lot.  Bring it to the shoot tomorrow.  And stop chronographing your bows if you like the way they shoot.

Dan
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Dan Raney

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