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Main Boards => PowWow => Topic started by: CanadaCanoe on February 10, 2010, 08:41:00 AM

Title: How do I measure center cut?
Post by: CanadaCanoe on February 10, 2010, 08:41:00 AM

I'm using this dynamic spine calculator, and it is lots of fun.

My Bear Montana claims to be "cut on center".  I have a Chek-mate Crusader that looks to be off center a bit more.  Is there an easy/accurate way to measure just how much off it is?

It looks, from the calculator, that this difference can be quite significant.  True?

Thanks!

Title: Re: How do I measure center cut?
Post by: sou-pawbowhunter on February 10, 2010, 09:04:00 AM

I'll be watching this one too.

Title: Re: How do I measure center cut?
Post by: moebow on February 10, 2010, 09:48:00 AM

This has come up many times lately, and here is my approach to it.  It is kind of "fiddly" but it works for me.

In order to find the amount of center cut on any bow you MUST establish the center line of the bow through the handle area.  Since the handle is usually sculptured in shape (that is curved lines rather than straight) any measurement around the handle area will probably not give you what you want.

A way to get the center line is
1.  Draw a long straight line on a large piece of paper  -- long enough to reach both the top and bottom fade out areas.  This is normally the widest part of a bow and will work for all bows, take down or not.
2.  Carefully measure the width of the bow at the fades and draw a second line on the paper parallel to the first line and EXACTLY the measured width of the bow.
3.  Establish and draw a third line that is EXACTLY half way between the first two lines.  This is the center line of the bow!
4.  This may need aother set of hands to hold the bow.  Lay the bow carefully and exactly between the width lines that are on the paper.  Make sure that the bow's fade areas are between the lines!
5.  Use a square or something that will let you establish the perpendicular line from the strike plate to the paper.  Place the square on the paper and gently slide it up to the strike plate.  The corner of the square on the paper is the spot you want.  Make a mark at this point on the paper and then you can remove the bow.
6.  Measure the distance from the center line to the mark on the paper and there's your center cut measurement.

I know this sounds too complicated but it works for me and I don't have to worry about the geometry of the riser.  I gives me really good results with Stu's calculator and allows for strike plate thickness differences which can throw off the boyer's advertised center cut measurement.

Title: Re: How do I measure center cut?
Post by: Predator Man on February 10, 2010, 10:02:00 AM

This is what I do.... Lean the bow aginst the wall. Back up a few feet and align the string with your eye where it runs up and down the center of the top and bottom limb.  As your eye follows the string up and down to lign it up center notice if the string clears you side plate (or riser if you have no side plate yet) or not.  Cut TO center is not center after you install a side plate.  Very few bows are cut past center but some bowyers cut 1/8th past center so when you install a side plate it will be center cut.  This technique works very very well.  


If you have a front mount takedown then they make a compound center tool you can buy to tell if your center or not. It plugs into the allen holes of the limb screws.

Now for my opinion.  Its good to know the exact spine of your arrow. Its a waste of time to think you can calculate what spine you need without shooting a few different arrows and seeing what works best.

here is where I usually start.

Assumptions are that you draw 28"

bows 42-43 pound or less  30" arrow .600 spine with 75-150 grain tip

44-53 pound 30" arrow .500 spine (gt 3555) with 100- 150+ grain tip

54-63 pound 30" arrow .400 spine (gt 5575) with 100 to 150+ grain tip.

63+ pound bow 340 or 300 spine (gt 7595) with who the hell knows... I cant pull a bow this heavy and if I needed this much weight to kill something I will use the bow for firewood to keep warm at night and hunt with a gun.

Remember fred eichler took the super slam with [email protected] so if you draw 28 thats probably a 58-62 pound bow depending on your bows speed.

Title: Re: How do I measure center cut?
Post by: Old York on February 10, 2010, 11:08:00 AM

(http://i816.photobucket.com/albums/zz85/6MightyMaus9/Centre-cutmeasuring.jpg)

Title: Re: How do I measure center cut?
Post by: NDTerminator on February 10, 2010, 01:13:00 PM

I called the manufacturers of my bows and asked them...  :D

Title: Re: How do I measure center cut?
Post by: CanadaCanoe on February 10, 2010, 06:45:00 PM

I appreciate the thorough responses.  I'm sure they would work, but "work", I try to avoid.

As such, I think I will just go shooting.  I like Predator Man's approach.

Just for a final piece of advice, though.  Is it at all likely that if I buy a dozen CE150's or GT3555's they won't work?  I draw about 26" on a longbow that is 51# at 28".

If I slowly cut one down while shooting and then fiddle with point weight should that work?

Thanks again.