There is an old saying, "Don't reinvent the wheel". However, if we never reinvented the wheel, we would still be stuck in a Fred Flintstone society with Fred Flintstone Cars yabadabadoo'ing our way down town, walkin' fast, faces pass and we're homebound. So therefore, I am literally reinventing the wheel. Here is the latest technology in print in place bearings.
Second Version is just a few touchups. The basic one has a clearance of 0.1 mm, the one with a tighter clearance has a clearance of 0.05mm. A 6 roller variant was also added for people with printers that can't print a 0.8mm rod.
Remember, if your prints have elephant's foot, then this tiny bearing obviously will not work after printing due to parts fused or warped geometry. So if you never tuned this issue out of your printer, print with a raft. Remember this is actually a pretty difficult print with a number of small parts, it will be advisable to print slower just incase. That being said, my ender 3 pro handled this print with pretty standard print settings.
Other tips include changing Z-seam alignment to random and also lowering flow rate.
It is very simple to free this bearing. Hold the center, and roll it furiously against a bed or couch cushion until it feel's relatively free. This will wear out all the random imperfections and smooth the overall shape.
So what makes this bearing so special? How is it any different from any of the other random selections out there? Well let me tell you. This bearing was designed with absolutely minimalizing contact area of the rolling elements. Most of the other bearings, except the massive herringbone gears, have 2 lines of contact on the rolling element. Normally, on a simple cylinder this doesn't affect the friction. But most designs feature cylinders shaped in a way with the housing that the parts will not fall out by changing the radius certain heights. These shaped cylinders will roll at slightly varying speeds and have areas with different speeds in contact with one another causing a lot of friction. My design only has 4 points of contact, 2 on each housing, and all those points will pretty much never have differing speeds at points in contact that cause friction.
How this is achieved comes from the shape of the rolling elements. These rolling elements work off of the same theory as the conical shape of train wheels. The conical shape when rolling down a rail will naturally self align to the center without intervention. With this in mind, the rolling elements in this bearing rolls on rails that are in the housing. There is also a built in flange in the bearing to keep the them from falling out. While not normally used in operation, the flanges keep the bearings bearing from derailing, similarly to trains. The size of the flange is still kept to the minimum to reduce friction in the event that the flanges are in use.
Another element as to why this bearing is different is the method of keeping the rolling elements in the correct positions. This design has a very off hand approach to securing the bearings, in a sense that they will only be corrected if it moves too much out of range. If the bearing was to move out of range, only a very small section at the top and bottom of the bearing will actually come into contact to keep it from moving too much. Otherwise it is highly reliant on the geometry naturally correcting itself. This further reduces friction as it reduces the amount of times the bearing is in contact with parts correcting it.
It has come to my attention that the flange is useless in the standard variants with 0.1mm of clearance between the rolling element and the rails. However the theory still stands and is actually useful in the 0.05mm clearance variants.
To everyone saying this is useless or isn't better than normal ball bearings
Of course it isn't, this is 3d printed; since when is 3d printed mechanical objects better than the standard. This is just for people who want a 3d printable bearing that has very low rolling friction and load. Nobody wants to waste premium ~1.00 USD 608 bearings which (obviously) have superiors load, thrust, speed, friction, reliability properties when all they needed was low friction and cheap.