2020 Carriages for Zero-Backlash Magnetic Arms

thingiverse

These carriages work with 2020 aluminum extrusions and 24mm diameter wheels, such as the ones from OpenBuilds or RobotDigg.com. Eccentric spacers are used for preloading tension on the wheels. You can get ball studs from me for $1 each, and I also precisely build carbon fiber zero-backlash magnetic arms. My website is http://www.MagBallArms.com. This design works well with my effector that sports an LED light ring and 3 PLA cooling fans: http://www.thingiverse.com/thing:1546124. Here are links to the wheels, eccentric spacers, and 1/4" round spacers from RobotDigg: http://www.robotdigg.com/product/521/Delrin-or-SUS-Via-S-Bearing http://www.robotdigg.com/product/626/Openbuilds-decentration-post http://www.robotdigg.com/product/670/Spacer-for-Delrin-Slide-Kit. Here are links to the wheels, eccentric spacers, and 1/4" round spacers from OpenBuilds: http://openbuildspartstore.com/delrin-v-wheel-kit/http://openbuildspartstore.com/aluminum-spacers/(choose 1/4")http://openbuildspartstore.com/eccentric-spacer/(choose 1/4"). Per carriage, you will need 3 of the above V- or W-wheels, 2 of the above 1/4" spacers (or 6mm), 1 of the above 1/4" eccentric spacers (or 6mm), 3 M5x35 bolts, 1 large M5 washer for the top side of the eccentric spacer (optional), 3 M5 nylock nuts to secure the three axles, 2 3/8" ball studs, 2 M3 nylock nuts to secure the ball studs, 2 M3x35 SHCS for the tightener, 2 M3 nuts for the tightener, 1 M3x20 SHCS for the vertical post for the upper G2 belt attachment, and 1 M3 nut to secure the vertical post. Note: You can easily alter the OpenSCAD source to work with 2040 or 2060 extrusions by changing extrusionWidth from 20.0mm to 40.0 or 60.0mm. If your belts are farther above your carriages, you can adapt using a longer M3 vertical screw. The belt tightener used is simple and easy to adjust with two M3x35 screws. I found that this delivers better results than using zip ties. My prints got more accurate by about 50 microns. I also have a version for 15mm diameter "mini" V-wheels: http://www.thingiverse.com/thing:2183355. Print Settings Printer Kossel Plus Rafts No Supports No Resolution 0.5mm Infill 40% Notes I tried to design this to be especially easy to print. I used PLA and didn't use any supports.