LockSleeve BCAR

thingiverse

This is the LockSleeve BCAR. It's what I use for competitive matches, and I think it's pretty damn good. It has two pieces: the Core, and the Sleeve. The Core has 6 "fingers" that sit around the barrel and are flexible. The Sleeve has ramps around its ID that push those fingers down against the barrel as you rotate the Sleeve around the Core. This causes the LockSleeve to very firmly lock itself into place and positively center it due to the rotational symmetry of the forces applied. It also doesn't need any hardware outside of the bearings and pins, so that's pretty cool. It uses F683ZZ bearings - 3mmx7mmx3mm, and uses 3mm diameter pins to hold them in place. Any length from 10 to 16mm should work, but I usually use 12 or 14. The original version is the 5x5 - a total of 25 bearings. If that's too many for you (I get it), there are also 3x3 versions available. I haven't tested them but they use the same geometry as other 3x3 BCARs I've made so I'm sure they'll be fine. The 5x5 perform better but for nearly 3x the cost it may not be worth it for everyone. Print the Core muzzle-down and the Sleeve muzzle-up. The 3x3 Sleeve fits all the different angles of 3x3, and the 5x5 Sleeve fits all the different angles of 5x5. The Wrench fits all of them. After printing, manually gently push each of the 6 fingers to make sure they can move (sometimes they get a bit sticky from the overhang and need breaking free). Then put the Sleeve onto the Core. You'll notice there are 3 nubs inside the Sleeve and 3 slots near the vents of the Core. Line the nubs up with the vertical cutouts in the slots to get the Sleeve all the way onto the Core. Don't twist the Sleeve yet or you won't be able to get it onto the barrel. After getting the Sleeve on the Core, put the combined unit onto your barrel, grab the Wrench, and get it into place on the hexagonally-shaped section on the bottom of the Core. Hold the Wrench steady to keep the Core from spinning, then grasp the Sleeve firmly yet gently (the Sleeve is fragile at the vents - be careful not to snap it by grabbing too tightly). You want one hand on the Wrench and one on the part of the Sleeve that's over the fingers. Then twist the Sleeve around the Core until it clicks. The nubs will prevent it from over-rotating. Once the Sleeve is rotated into place, you're done. The first few times, it may be a little too tight depending on your printer's tolerances. If you're worried that you'll break something, you can hit the OD of the finger region of the Core with some sandpaper to lower its diameter ever-so-slightly. This is being released as Non-Commercial. If you're just making one for a friend and charging for the price of materials, I won't be upset about it. If you want to do anything more than that though, hit me up so we can arrange something. This whole thing is parameterized to hell in my Fusion file so if you need some special case - some other angle or bearing arrangement, for instance, shoot me a message.