Walking with my dog  in a city park i found about 30 yards of fiberglass rod the kind they use to drive electric/comms wire into underground tunneling...  so i made  an early Saturday morning trip with a bolt cutter and i metabolized the whole thing into manageable rod lenghts of 2 and 1.70 metres.
The stuff is amazing! It's 1 cm diametre  with a fibberglass core and an external layer of plastic that looks etreme wear resistant.
I've made a prototype compound bow with  5 rods , 3 rods of 1.60 metres, backed by 2 rods  of 65 cms, and may be i add another rod of 65 cms or sightly shorter in the back of the last 2 rods, making a triangular pile of 6 rods like this...
  o
oo
ooo
I've found i have to group the 3 rods with a nock in both ends to tie the string  properly and i've done 1st experimental assembly with electrical duct tape.... it feels very nice and powerful. (i guess final assembly will be power tape and paracord)  Nocks will be aluminium or plywood epoxied and tied with paracord or strong thread.
Any ideas about improoving it?  any advice about compound bows?

Check over at the archery part of paleoplanet. I remember seeing a similar post there in the last few days. Unless that is your post too. I was thinking and a compound could probably made. I'm no expert but you need eccentric wheels. Round wheels are no good because they make the draw too short. The other thing that struck me is that the tips on your bow are probably going to be way, way to heavy. If so your bow is gonna shoot like crap. No offence. Maybe try to made two longbow style bows using less rods and tapering to the tips? Or use them as crossbow prods.

lol mike, yes it was a post of mine too
I guess i'll have to experiment, with bow lenghts.... too long and it will flex so easy it will have very little force, too sort and it will be so stiff i would  need 3 times my arm muscles to draw it.
The only way i can tapper bow ends is decreasing rod lenghts as i add them to the back of the bow, now i have 3 long rods in the front and 2 short in the back, may be i have to invert the numbers... 1 long rod in the front, 2 shorter in the back and may be 3 even shorter in the very back, this will give me  light ends and stiff center in the bow. Also this way i won't need nocks, just carving a notch to place the string... i'll post pics of the thingie
BTW paleoplanet was under attack and lost almost all its files, i hope Chris and the rest of  slinging.org staff have all this invaluable info in a safe place and keep backups 

ya that was crap. On a related note I've never been able to post over there. I never got a email to confirm my login. What's up with that?

Zorro, I was thinking that if you got some fiberglass cloth and the epoxy you could arrange the rods how you want them and then fiberglass them together. Wrap them in glass and form a single unit out of them.

After some testing, finally i used 2 paralell rods of 137cms and 1 rod of  65 cms in the front and another same lenght in the back in a diamond config
o    <----  1 short rod of 65 cms in the back of the bow
oo   <---- 2 long paralell rods of 137 cms
o    <----   1 short rod of 65cms

This config feels ok  and i think is a lot more powerful than my last bow,  a longer back rod of 85  or 90 cms instead of 65cms may add some more power, but by now it's ok
Rods are tied together with power tape  (not much "paleo" anyway uh?  8) )

Quote:


agreed

'Nyestry Lighter meer ya DOBRY communist' , as I learned as a child, Just in case- thats 'please don't shoot me, I am good communist' phonetically.

Not much use now of course..... unless Cuba starts punching WAY above their weight division.

finally my 3rd prototype is  as follows:

oo  <---2 paralell  rods 134 cms (back of the bow)
oo   <---2 paralell  rods 94 cms
oo    <---2 paralell  rods36 cms

Had to trim the short rows more than 5 cms each side cause it was so powerful i couldn't draw it  full lenght.
also have some problems trying to avoid rod displacement, so i guess i'll add some aluminium rings to keep rods in place.
i'll post pics asap.