Author Topic: Shelf hight and effects off arrow (design ?)  (Read 505 times)

Offline T Folts

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Shelf hight and effects off arrow (design ?)
« on: August 14, 2010, 06:27:00 PM »
I am building 3pc longbows and basically it is the binghams limbs on a 16" riser. The last bow I built the shelf was cut at 1" above center. Center being center of bow and center from tip to tip.
When tunning my bow the arrow needs to be 15/16 above the rest in order to stop the arrow from smacking off the shelf. What can I do to prevent the next bow from behaving the same way. Should I raise or lower the shelf from center. If you look at the bow from the side with an arrow nocked it looks like it is pointing down with the bow vertical.
Any ideas or suggestions would be greatly appreciated.
Thanks
Terry
US ARMY 1984-1988

Online Roy from Pa

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Re: Shelf hight and effects off arrow (design ?)
« Reply #1 on: August 14, 2010, 07:10:00 PM »
When I lay out my bows, I mark the center of the bow, tip to tip, then measure up 1 1/4 inches and that in my arrow shelf/top of handle, then I measure down 4 inches from that and that is the bottom of my handle. Sometimes when tunning and you get the string nocking point too high, it will have a reverse effect on arrow flight and the nock of the arrow will fly down ward and hit the shelf. Where did you start out at with the nocking point on your string? I would start at about 1/4 inch and see what happens.

Offline T Folts

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Re: Shelf hight and effects off arrow (design ?)
« Reply #2 on: August 14, 2010, 09:19:00 PM »
Roy don't take this wrong I know how to tune arrows my question was more of the physics in shelf placement verses nocking point. If I raise my shelf or lowered my shelf placement what would that do ect..
I did lower my nocking point almost to zero during the tuning process.
Thanks
Terry
US ARMY 1984-1988

Offline GREG IN MALAD

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Re: Shelf hight and effects off arrow (design ?)
« Reply #3 on: August 15, 2010, 02:24:00 AM »
How much positive tiller does the bow have? It sounds like it has too much. Are you shooting split finger or 3-under? For split finger I use 1/8" to 1/4" positive tiller and even tiller for 3-under. I cut all my shelf's 1" above center and all my bows tune in around 1/2" above square. What type arrow shaft and rest are you using?
I didnt miss, thats right where I was aiming

Offline T Folts

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Re: Shelf hight and effects off arrow (design ?)
« Reply #4 on: August 15, 2010, 07:58:00 AM »
Greg
The bow has 1/4" positive tiller. I am shooting split finger and I am shooting Gold tip 33/55.
Terry
US ARMY 1984-1988

Offline T Folts

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Re: Shelf hight and effects off arrow (design ?)
« Reply #5 on: August 15, 2010, 08:09:00 AM »
Greg
What kind of bows are you making?
US ARMY 1984-1988

Online Roy from Pa

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Re: Shelf hight and effects off arrow (design ?)
« Reply #6 on: August 15, 2010, 10:13:00 AM »
Not a problem Terry. I would go a little higher with the shelf on the next bow. Sounds like one of your limbs may be kicking the arrow. How does the tiller look at full draw?

Offline GREG IN MALAD

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Re: Shelf hight and effects off arrow (design ?)
« Reply #7 on: August 15, 2010, 01:00:00 PM »
Terry,
 I build one piece longbows and recurves as well as 3 piece take down longbows, along with the occasional wood bow.
 15/16" above square is really high for 1/4" positive tiller. I have had problems with carbon shafts bouncing off leather rests, switching to velcro fixed the problem. I would suggest removing a little weight from the bottom limb and try 1/8" positive tiller.
I didnt miss, thats right where I was aiming

Offline T Folts

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Re: Shelf hight and effects off arrow (design ?)
« Reply #8 on: August 15, 2010, 01:07:00 PM »
I have a velcro rest so I'll look at the tiller.
Thanks
US ARMY 1984-1988

Offline T Folts

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Re: Shelf hight and effects off arrow (design ?)
« Reply #9 on: August 15, 2010, 02:44:00 PM »
Well I think I figured out the tiller issue, my center of my grip was 1/2 inch lower than the center of my bow making the top limb longer adding to the 1/4 inch positive tiller. I'm thinking the bow is behaving like a 1/2 positive tiller so that make things more clear... stay tuned..
US ARMY 1984-1988

Online Roy from Pa

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Re: Shelf hight and effects off arrow (design ?)
« Reply #10 on: August 15, 2010, 02:51:00 PM »
Glad you fuggered it out Terry, good job ^5.

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