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<DIV><FONT face=Arial size=2>We will assume that the shafts are straight
and the table of the crossbow is flat and smooth, and that the string travel
along the entire power stroke is smooth and even (not the string touches the
table when cocked and is half-inch above the table when at rest
or vice-versa).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>We will also assume that a good fletching job was
done and the fletches regardless of how may are there are straight,
symmetrical, evenly spaced, and don't drag the table of the crossbow
excessively. If you have a tight helical or big offset fletch or if the
bolt channel is too deep then the front of the fletch can drag on the table
on one side and the rear on the other and that can (not always) throw
things off.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>
<DIV><FONT face=Arial size=2>We will also assume that if you are using a
Jo-Jan jig to fletch them then hopefully you are using a </FONT> <FONT
face=Arial size=2>F-51, F-61, or F-71 nock receiver setup for 4-fletch and
turning 2-clicks to set each fletch so that they are 180 degrees apart. A
3-fletch receiver setup only using 2 fletches would not really be
good.</FONT></DIV></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>All the above should be pretty easy to inspect
for.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Now, define what ya mean by "corkscrew".
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Hopefully they aren't flipping end for end
vertically (what most people call cartwheeling) and hopefully they aren't
flipping end for end horizontally (what most people call helicoptering).
If they are doing that then they are more than likely WAY off balanced and
too heavy on one end.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I say WAY off balance because weight balance is not
nearly as important on crossbow bolts as it is on arrows. Arrows gain lift
by "point planing" and for this reason the balance point on an arrow
should be about 9% front of center. The weight balance on a crossbow bolt
is not nearly that important and it can be fore of center or aft (or dead
center) as long as it is not WAY off to one end.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If the bolt ends bouncing up and down (but not
flipping end over end) then that is usually called porpoising. If the end
of the bolts are wagging side to side then that's typically called
fishtailing. For handbow archers popoising is usually a nocking point that
is too high or low and fishtailing is usually a bad release.
For crossbows these can be bad bolt balance, bad fletching, a bad release
off the bow, a bow that is pulling unevenly, and a bunch of other things.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>A cork screw where the tail of the arrow is moving
in circles is often a bad fletching job or otherwise a combination of a several
factors (something making it fishtail and something making is porpoise).
And there is something else it can be, read on...</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I said earlier that balance isn't as critical on
crossbow bolts, and neither is spine. Since crossbows are "center shot"
and there is no archers paradox where spine is critical. It's a good thing
that spine isn't a real issue for crossbows since shortening a shaft by an
inch increases the effective spine by about 3 pounds. So ya cut 10 inches
off a shaft and ya add an effective 30# of spine to it. Additionally since
the bolts is supported by the table of the crossbow and cradles in a
groove that adds stiffness. So if spine where critical
then a lot of crossbow shafts would be way over spined.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So if weight balance isn't critical and spine
isn't critical then what is?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>DRAG! </STRONG></FONT><FONT
face=Arial size=2>and the relationship of the drag to the weight
balance.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The center of the drag should be slightly behind
the center of the balance. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Without good modeling software taking into account
specifics of all your materials it is very hard to determine precisely
where the center of drag is. However you can easily adjust the center of
drag and you can adjust the center of balance so that the bolt will fly
right.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>
<DIV><FONT face=Arial size=2>Since the weight balance is usually forward of
center (particularly on crossbow bolts) usually the problem with crossbow bolts
is that the center of balance is far forward (from the weight of the point) and
the center of drag is far to the rear (from the drag of the
fletches). If those problems get too excessive then the two ends of the
bolts are fighting each other for control of the bolt while it is in
flight.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Obviously heavier points will move the balance
farther forward so try to get the lightest points that you can get to allow the
center of balance to come as far back as ya can to center or just forward of
center. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>More fletch will move the drag further back.
When I say "more" I mean physically larger fletches or a larger number of
fletches (3 instead of 2). Helical fletching or offset fletching also adds
more drag. Use smaller fletches to move the center of drag
forward. 2" is usually the smallest feather fletches you can find but
you can always cut your own. Straight fletching instead of helical or
offset will also allow the center of drag to move forward.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You wanna make all these factors come together and
make a bolt whose point of balance and center of drag are in harmony and working
together for a smooth flight. Play with the diameter and weight of your
shafts, the weight of your points, and the size, number, and angle of
fletch.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If you put your points on with a holt melt glue
then it will be easy to play with point weight and see if that changes
things. If you originally used a heavy point then take one off and try
successively lighter ones and see if it appears to get better or worse. If
you originally used a lighter point then try successively heavier
ones and see if it gets better or worse.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>If ya cant fix it with points then you'll need to
try refletching. 4" fletches have likely pushed your center of drag way
back. Take the same bolt you have been playing with the points and
refletch it using smaller fletches and with a straight fletch and see what
happens. You can take some of your 4" parabolic fletches and VERY easily
with a sharp pair of embroidery scissors cut then down and make smaller
fletches of the "traditional" shape.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>To fix center of drag and balance problems s<FONT
face=Arial size=2>ome people will simply use longer shafts.
They learn that using the same points and fletches that they can just
use approx X weight shafts cut to X length. Longer shafts will
have a tendency shift the balance point backwards and the center of drag
forwards. While sometimes that is easiest way to correct things, it isn't
necessarily the best. Longer shafts are more likely to break, more likely
to bend and not stay straight, and are of course heavier and add to overall drag
so that you are going to lose cast as compared to the shorter, lighter, well
balanced bolts. Barrel tapered bolts (very period) will move the balance
towards the center of the bolt and decrease drag both while in flight and
friction/drag along the face of the crossbow during launch. Of course I
don't know anywhere you can buy barrel tapered crossbows bolt length shafts so
you would have to taper your own.</FONT></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2>Good luck. Tinker with your bolts and HAVE
FUN. My experience is that it is harder to get bolts right than it is
arrows. When you get them right if you have taken your time to figure out
exactly what was wrong and why they are now right then you will have
learned a lot.</FONT></DIV>
<DIV><FONT face=Arial size=2> </FONT></DIV></DIV>
<DIV><FONT face=Arial size=2>Regards,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>HL Eadric Anstapa<BR>Ansteorra<BR><A
href="mailto:eadric@scabrewer.com">eadric@scabrewer.com</A></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=5>WHEN YA TYPE IN ALL CAPS IT SIGNIFIES
SHOUTING</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=ld.blackmoon@gbronline.com
href="mailto:ld.blackmoon@gbronline.com">LD.BLACKMOON</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=ansteorra-archery@ansteorra.org
href="mailto:ansteorra-archery@ansteorra.org">Archery within the Kingdom of
Ansteorra</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, December 14, 2003 7:21
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [Ansteorra-archery]
corkscrews...</DIV>
<DIV><FONT face=Arial size=2></FONT><BR></DIV>
<DIV><FONT face=Arial size=5>greetings</FONT></DIV>
<DIV><FONT face=Arial size=5></FONT> </DIV>
<DIV><FONT face=Arial size=5>ok, this is probably going to be a stupid
question ...</FONT></DIV>
<DIV><FONT face=Arial size=5>but , i just made my first 1/2 dozen crossbow
bolts , from old 11 / 32 arrows , using 4" parabolic fletching . </FONT></DIV>
<DIV><FONT face=Arial size=5>and every last one of them has a severe corkscrew
every time i fire it ...</FONT></DIV>
<DIV><FONT face=Arial size=5>so ...</FONT></DIV>
<DIV><FONT face=Arial size=5>a: what did i do wrong ???</FONT></DIV>
<DIV><FONT face=Arial size=5>b: how do i fix it ???</FONT></DIV>
<DIV><FONT face=Arial size=5>c: what causes it ???</FONT></DIV>
<DIV><FONT face=Arial size=5></FONT> </DIV>
<DIV><FONT face=Arial size=5>oh, i'm using a jojan jig, and 2 fletching them
.</FONT></DIV>
<DIV><FONT face=Arial size=5>thanx</FONT></DIV>
<DIV><FONT face=Arial size=5>ld.blackmoon</FONT></DIV>
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