608 'Skateboard' Bearing Sheave Block
Description
I needed cheap, low-working-load sheave blocks for theatrical rigging to fit 3-4mm VB (Venetian blind) polyester cord, so I decided to design some that use ubiquitous & cheap 608/608ZZ bearings for smooth running. I had a bunch already and know they're commonly available. I decided that rather than relying on part fit or glue to hold the block together, or the added width of a bolt & nut as axle, I would use 1.5mm galvanized steel wire.In theory, the wire also provides additional force transfer from the block to the axle and bearing, for added strength. # Loading / Warning **This design has *no* SWL (Safe Working Load) Rating! It is not certified for any capacity.** Do not use this design for flying or rigging where there is a risk of injury to people or animals. I have not yet tested these with any greater load than approx. 10kg, nor over sustained time. Please use carefully and conservatively! # Construction I have printed several in PETG and adjusted the fitment for my 3D printer. I recommend to try the 'ready-to-print' files with all three printed parts laid out nicely for slicing. **Print settings tested: PETG, 0.2mm layer height, 60% infill, no supports, no brim** There is a recessed path for the binding wire through the centre of the axle, and folded back through two through-holes higher up. Using pliers, the wire (1.5mm galvanized 'fencing' wire) should be cut to approximate length (~90mm), inserted through the axle & centred, sharply bent along the recesses and to go through the holes. Push it flat into the recess, pull tight from the other side, then trim to leave approx. 3mm sticking out each side. Fold that remaining length into the short recesses to lock the block closed. ### Fitment If you have dimensional/fitment issues, open the Fusion 360 archive file and adjust the values in the face offset steps in the timeline. As I understand it's unreasonable to expect everyone to have access to proprietary software, I'm also happy to help with providing modified files if you send me a message here on Thingiverse or via Mastodon (@s0@cathode.church). You adjusting to larger sheave sizes but I haven't tried yet.
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