About raffiots

Feb. 22, 2010
Total Views
Full Profile »

Tell us about yourself!

Complete Your Profile
  • raffiots commented on Yoshinok's instructable Make a takedown bow from skis!7 months ago
    Make a takedown bow from skis!

    I've made three of these bows over the course of the past two years, and I've got to say they're great! At 25-30 lb, depending on the riser design, they're great for lighthearted archery fun. You're not going to go hunting, and you're not going to make a half-dollar grouping at 20 yards, but you are going to have a wide grin on your face as you and your friends volley fire medieval style at a pizza box.I also find these great for first-time adults, who want to try shooting a bow, but who I really don't want to hand my 55-lb compound, or even my 40# recurve. Much less intimidation for the first-timer, and much less worry for me. And now for science: I built a rig to test different riser lengths, limb angles, etc... and on that rig i've tested multiple sets of cross-country ski limbs for draw weight. I've gotten a few sets up to about 48 # at about 26". Some of these are fiberglass exterior with a plastic core and some are fiberglass exterior with a wooden core. The wooden core are significantly stiffer and will yield a higher draw weight at a shorter distance.I've only had one set of limbs fail on me, and they failed exactly how I thought they would. I accidentally left one of the bows strung overnight, and when i came back in the morning, the limb had collapsed inward by about 20 degrees. The plastic layer on the bottom of the ski failed in compression, and crumpled under the constant, low load. With the plastic-core fiberglass skis, this is the failure mode that I would expect, as the fiberglass top layer should be very strong in tension. (however, if it is over tensioned, it will fail rapidly and possibly violently.. be careful!) This is why I always un-string my ski bows, and I usually keep their poundage under 30. I'm pretty confident that at this weight, the materials are more than strong enough. As always, remember that you are re-purposing and object that was not designed for this use. If you feel like something isn't right, stop, un-string the bow, and be safe. Wear eye protection, and use common sense!Go make a bow!

    View Instructable »