I remixed migthynozzle's linear bearings https://www.thingiverse.com/thing:2202854 to get rid of the original aluminum bearing holders. I have an Anet A8 and their quality is horrible sice the screwholes are sometimes more than 1mm away from their intended position.
Since I really like the IGUS like bearings, I took them and added a holder with which they can be used for bothe the x- and the y-axis.
Their size is LM8UU. If you need a differnt size, please add a commet and I'll see what I can do.
The holders can be attached by adding 4 M4 nuts with a height of 3mm to the corresponding holes.
If you have any problems or further questions, please write me a comment.
If you like it, you may also check out my other Anet A8 and 3d printing things:
To be able to print bearings that can be actually used, you need a highly calibrated printer. The printer should be able to print with an accuracy of approximatly 0.1 mm in x- and y- direction and no z-wobble or something like this. This is only achievable if your belts are tight enough, so you will probably need to print some other improvements first.
Since I have no idea how to get this 3d-Model into OpenSCAD, the model is not customizeable like the one I remixed. Since there is basically only one size that has to be varied, which is the inner diameter of the bearing, I added stl-files for diamters between 8 mm and 8.5 mm. If you need a larger or a smaller one, please write a comment.
The screwholes and the holes for the nuts are 0.2 mm larger than they are supposed to be to compensate for printing tolerances. Their heigh is also 0.2 mm smaller than the original one.
You should start printing a bearing with an inner diameter near 8.25 mm. After it finished, take a rod and try how well it is fitting. If its too loose, print a smaller diameter, if its to tight print a larger diameter until you find the best fitting one. If none of the diameters fits perfectly, print the next smaller one and push the rod through it multiple times. By that you remove a small ammount of material and suddenly the bearing will fit perfectly.
If your printer suffers from z- wobble or other inconsistencies between the different layers, you need to fix that first, otherwise you wont reach the required accuracy.