Printer friendly caged roller bearing

thingiverse

A Totally Awesome Printer Friendly Roller Bearing Print-in-place mechanical things are simply fantastic, especially those that can actually be used for something. Maximum kudos for things that can't be manufactured any other way! A pre-assembled ball bearing fits all of this perfectly, but sadly it's not really possible to 3d-print a ball bearing that is anything more than a curiosity, since the balls can't be round if they are to stay in place while being printed. But roller bearings should be achievable, and indeed there are plenty of designs for print-in-place roller bearings here. I have tried numerous ones, and one thing is immediately apparent, the rollers have to be caged. Free running rollers have too much friction as the rollers are grinding against each other, and they will not roll straight causing a very jerky motion while being under load. A great cage should keep the rollers running straight on the races, and that should in theory eliminate the jerky motion. I have tried several ones and I have always been disappointed with how they roll in practice, or they wouldn't print correctly at all due to unprintable details. One common "unprintable detail" is a curved bridge on the upper side of the cage. Another is that the roller footprint is too small to hold them in place while printing. I always had a feeling that it should be possible to work around the limitations of 3d printing and have a design that at least in theory would work perfectly. This design at least comes closer to that. The main 'innovation' is that all bridges are straight, which should make printing much less of a hazard. Clearances are sufficient with margin so the cage doesn't come into contact with any of the races, nor with the roller sides, making the extra friction from the cage very low. Finally all overhangs are kept reasonable, and there are no sharp pointy overhangs that tend to curl up and cause problems. ### Printing The .stl file has the dimensions 10x42x12. I have set the clearances so it comes off the building plate more or less ready to spin, but that means it isn't very tight. But nothing is more disappointing than printing a bearing that is completely fused together, so I want to avoid that. There is also a *loose* stl, that has additional clearances if the first one is stuck, and a *tight* version that needs a little work to break free on my printer but then it runs *really* smooth. It's a good idea to split the file in your slicer before slicing so each roller is sliced independently. Using e.g. *triangles* infill pattern in Slic3r makes a nice symmetric infill in the rollers this way. Don't forget to set 'seam position' to 'random' (slic3r setting, something similar probably exists in all slicers), otherwise the rollers and races will have a noticeable seam on one side. ### Source code included FreeCAD source code is included. The design is somewhat parametric, inner and outer diameter can be set within limits, and the width can be anything from 12mm and up. These plus the main clearances can be set from the *settings* spreadsheet, and the rest by modifying the sketches. ### Some remixing examples: - toy wheel: https://www.thingiverse.com/thing:3247096 - pulley wheel: https://www.thingiverse.com/thing:3253703 - spool holder: https://www.thingiverse.com/thing:3459522 A video of the spool holder in action: https://youtu.be/xqMAyEoEzUE