Zero-Backlash Magnetic Ball Joint Rod Ends

thingiverse

These are designed to work with 3/8" balls, 0.230" diameter carbon fiber rods, and N50 cylindrical magnets which are 10mm in diameter and 15m high. Description This can be printed with a layer height of 0.2mm or 0.1mm. I use 0.2mm. Use a shell thickness of 2mm or four layers, so that all of the walls will be printed with concentric circles, instead of back-and-forth infill. I use a 3/8" ball end mill to gently clean out the ball bearing sockets. Note: I have to print out two to four of these at a time, to get the correct dimensions. I use these with my magnetic effector: https://www.youmagine.com/designs/kossel-plus-magnetic-effector And magnetic carriages: https://www.youmagine.com/designs/kossel-plus-magnetic-carriage--2 Contact haydn.huntley@gmail.com if you need an inexpensive source for the ball studs or magnets. Note: This has been my most popular published thing on Thingiverse. Since designing these, I've had rod ends CNC machined out of Delrin, which work even better. I have them for sale for $15/set of 12. Also my CNC machined ball studs are $18/set of 12. Instructions Get a pair of 3/8" ball bearings and make a jig which you will use to make the resulting rods all be exactly the same length. The distance between the two ends of your jig should be should be 9.5mm+DELTA_DIAGONAL_ROD. 9.5mm is the diameter of a 3/8" ball bearing, and since your jig will have two of them inside it, subtracting the size of the extra half on one end and the extra half on the other end, will yield exactly DELTA_DIAGONAL_ROD. Nice, eh? Here is a link to my jig: https://www.thingiverse.com/thing:1546080 Note: the jig is shown in the last three images. Dry fit the parts together. I get my strong walled 0.230" tubing from TriDPrinting.com or Goodwinds.com. Mix up some 5-minute epoxy and glue first one end, and then the other, and then make sure it fits perfectly in your jig, while you let the glue harden. BTW, I sell these sized for a full-size Kossel/Delta printer (288mm from the center of one ball bearing to the center of the other) for $60/set of six, complete with ball studs. I use a large micrometer to precisely measure the arms and write the lengths on them. Here is a link to a page where I describe installing them and calibrating a Kossel Clear: http://www.maui-3d.com/kcZeroBacklashInstallation.php Note: If you use Rich Cattell's version of Marlin, and you accurately know the length of DELTA_DIAGONAL_ROD, you can use the "G30 A Dnnn" command to calibrate your printer in about 10 minutes. On my first printer, I spent a week trying to get it calibrated by hand, and finally gave up when it was "close enough"!