Ball Screw and Nut

thingiverse

It's a pretty neat demonstration of a recirculating ball screw and nut, even if it's not particularly useful. Most ball nuts feature several threads packed with balls, followed by a single long recirculating ball path. This version, however, is composed of three separate nuts, each with a single thread of engagement and a short "jump-over" section to recirculate the balls. Each nut is formed from two clam-shell halves. When all three nuts are assembled onto the screw, the jump-over sections for each nut (where there's no thread engagement) are counter-aligned. Three nut sections provide stable support to the screw at minimum. A clamp piece holds all of the nut sections together. This device uses 27 airsoft pellets (6mm) as ball bearings and three 4-40 or M3 socket head screws to hold the nuts in place. As a bonus, the balls don't all fall out when removing the nut from the screw! Print Settings Printer: UDIO Rafts: Yes Supports: No Resolution: 0.1mm Infill: 20% Notes: The nut halves are the only things that really need to be printed with 0.1mm layer thickness. The clamp and screw can both be printed with 0.2mm layers. Also, the screw is printed on end and it's the only piece that should be printed with a raft or brim to keep it stable during printing. Print six nut halves, one screw, and one clamp in total. Post-Printing Assembly After printing, use a small piece of scotch-brite abrasive pad to sand out any nits from the ball path in the nut halves. For each nut section, place one half on a table and carefully place 9 balls (I use tweezers) in the ball track. Then place the other half over it so that the little tabs interlock. Apply two or three tiny drops of superglue on the outside seam to temporarily hold the two halves together. Ensure none of the glue wicks into the ball path. Next, screw all three nut sections onto the screw until they're lightly touching. Then slide the three nuts into the clamp and secure with three M# or 4-40 screws.