T8 Lead Screw Nuts

thingiverse

When trying various lead length screws on my MK3 Bear's Z axis, finding POM nuts of the right size for anything other than an 8mm lead proved impossible. So, naturally, I made my own. I've found these custom-made nuts last 6-12 months on each of my three machines, but I recommend printing a few extra pairs to avoid frequent machine setup and material preparation. I printed these in nylon material - Essentium PA - which has worked out well for me. If you use another type of material that works, please let us know in the comments! Keep in mind that the screws are usually not hardened, so it's essential to use a low-friction material to avoid wearing them down. The nut should be the consumable part of this setup. Material Preparation: Get it dry! I used a vacuum chamber for 12 hours with the pump on, then stored the material with a liberal quantity of desiccant before feeding it into my printer in a SpannerHands MK6. Print settings that have worked best for me include: Bed Surface: Any surface with a generous helping of glue stick Bed Temp: 95c Nozzle Temp: 260c Nozzle: E3D Copper .25mm Extrusion Width: .26mm all around (small means sharper corners, thus a better-fitting part) Perimeters: 5 Layer Height: .15 (my nylon seems to like the 60% nozzle ratio) Infill: 20% Gyroid Skirt: None Brim: 10mm (nylon likes to pull off the bed, so big brims are required) Cooling: None Speed: 15-25 mm/s Enclosure: Use it if you have it; it should help with material warping. F360 Source files: T8, 2mm Pitch, 2mm Lead - https://a360.co/2J0gFDd T8, 2mm Pitch, 4mm Lead - https://a360.co/2TucnJ6 T8, 2mm Pitch, 8mm Lead - https://a360.co/2TD425n Make sure your extrusion settings are fine-tuned! Internal dimensions are critical for a nice fit. The thread profile has a 0.025mm tolerance offset, which feels great on the screws when printed on a well-tuned machine. If the nut is feeling too constrained, either adjust and reprint or load up a leadscrew in your drill chuck and run the nut on and off a few times to see if it just needs to be cleaned up a bit. My first attempts at printing these were with a .4mm nozzle, but they came out a bit tight. Using the drill to quickly break them in did the trick.