Freehand snatch block

My son is about to go camping, and wished for snatch blocks to hoist bear bags into trees more easily. I suggested that we had the stuff around the house to manufacture this ourselves, and make it much lighter (useful for camping) than the expensive high-load snatch blocks available for sale.

  • 1" polyethylene rod
  • ½" aluminum rod
  • ½" x ⅛" aluminum strap
  • 2 x M5*8 pan-head screws
  • 2 washers
  • loctite

Lathe: Used a 10mm round carbide insert as a form tool to make a pulley. Drilled it ½" through. Drilled and tapped ½" aluminum rod ¾" deep M5 (because I have appropriate M5 screws), parted it off ¾" long. This is a bushing.

Mill: Two pieces: Cut ⅝" and ½" holes at opposite ends of the aluminum strap, about 3" long. (The ½" hole about ½" from one end, and the ⅝" hole about ⅝" from the other end. ⅝" is just because it was a good match for some carabiners we have; choose hole size and corresponding placement to match.)

Vice: Bent the aluminum straps together near the ⅝" hole ends so that the ⅝" holes touch.

Put loctite in both ends of the aluminum rod.

Assembly:

  • M5 screw
  • Washer
  • Screwed into bushing rod
  • One strap over bushing
  • Pulley over bushing
  • Other strap over bushing
  • Other washer
  • Other M5 screw
  • Tightened solidly onto loctite

(On this first pass, the ½" holes are closer to the end than the hole diameter because we changed our mind about design partway through, and I could have rounded the edges on the straps. But for a quick and dirty low-load snatch block set, I was pleased.)

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Second set went way better and faster. Figured out how to bend the strap better, so it’s more even, and left more meat around the bushing for strength. This time I remembered to chamfer all the hard edges on the pulley.

The slight outward bend at the loose end of the strap means that when it is loaded, the straps will tend to pull away from the pulley and thus avoid binding.

I didn’t think to polish the outside of the bushing, and if we ever make another we’ll probably do that.

More pictures, just because…

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Got a report: The snatch blocks worked well. :tada:

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