Scott,

I have tried both aluminum and carbon arrow shafts.  It's easy to make =
fittings from aluminum sheet by wrapping it around a proper sized bolt =
or by using glass cloth and resin but you will have to use care in the =
design.  I have about 2 kg mass and the forces in the boom are to great =
for an arrow shaft (2215 xx75 about 28" long for example) with my =
support configuration.  If you do try the arrow, use a bit taller mast =
and fasten the support wire to the mass with the force line through the =
CG.  Hanging the mass outside the wire will induce a bending moment =
which combined with the compression is more than the shaft will handle.  =
I went to 1/2" x .035" wall aluminum tube simply because the arrow with =
2 kg on the end is very delicate.  I did continue to use an arrow insert =
epoxied into the partially compressed tube end and a field point as the =
pivot riding on an aircraft bolt head.  The point on the field tip is =
not satisfactory as machined and also tends to damage easily during =
setup due to softness. I have reground and hardened the temper and =
intend to add a tool steel point. With the insert it is only seconds to =
change the pivot. =20

I've considered the string material also but for me the cost is still =
out of line with any potential improvement.  If you have string material =
on hand, the strength and stretch properties certainly would make it =
worth a try.  It has totally replaced steel cables in archery for the =
same qualities of light weight, strength, and low stretch.

Welding up a base from steel angle is easy and practical.  I made a =
horizontal T and added an upright.  It doesn't take 30 minutes.  My =
leveling screws are threaded into the T but you could also epoxy or tack =
weld nuts to the angle.

Randy







Scott,
 
I have tried both aluminum and carbon =
arrow=20
shafts.  It's easy to make fittings from aluminum sheet by wrapping =
it=20
around a proper sized bolt or by using glass cloth and resin but =
you will=20
have to use care in the design.  I have about 2 kg mass and the =
forces in=20
the boom are to great for an arrow shaft (2215 xx75 about 28" long =
for=20
example) with my support configuration.  If you do try the arrow, =
use a bit=20
taller mast and fasten the support wire to the mass with the force line =
through=20
the CG.  Hanging the mass outside the wire will induce a bending =
moment=20
which combined with the compression is more than the shaft will =
handle. =20
I went to 1/2" x .035" wall aluminum tube simply because the =
arrow=20
with 2 kg on the end is very delicate.  I did continue to use an =
arrow=20
insert epoxied into the partially compressed tube end and a field point =
as the=20
pivot riding on an aircraft bolt head.  The point on the field tip =
is not=20
satisfactory as machined and also tends to damage easily during setup =
due to=20
softness. I have reground and hardened the temper and intend to add =
a tool=20
steel point. With the insert it is only seconds to change the =
pivot. =20

 
I've considered the string material =
also but for me=20
the cost is still out of line with any potential improvement.  If =
you have=20
string material on hand, the strength and stretch properties =
certainly=20
would make it worth a try.  It has totally replaced =
steel=20
cables in archery for the same qualities of light weight, strength, =
and low=20
stretch.
 
Welding up a base from steel angle is =
easy and=20
practical.  I made a horizontal T and added an upright.  =
It=20
doesn't take 30 minutes.  My leveling screws are threaded into the =
T but=20
you could also epoxy or tack weld nuts to the angle.
 
Randy