One of the most important things that you are going to need for your 3D printer build are the Linear bearings, or LM8UU bearings. As you shop around you are going to find these for prices between £1-3.00, these will be of a cheap low quality build, we know we have bought some (take a look at our guide to buying parts for your 3D printer build). Basically the inner retainer that holds the bearings in are of very low standard. So you have the option of buying premium quality bearings for £15-30.00 a bearing which is obviously way to expensive so we have come up with a good quality and low cost solution with our KG bearings.
Why by our LM8UU linear bearings
KG bearings is an Indian manufacturing of intermediate grade bearings. The build quality is very good and they run very smoothly, none of that grinding that you will experience with low grade bearings. This means that you smooth rods will last longer as well as your bearings saving you money in the long run. It will also save you time as you will have better quality prints due to their smooth running and you will not have to constantly take your 3D printer apart to replace bearings and smooth rods. The main difference is in the quality of the build of the ball bearing retainer that houses the bearings. Imperfections in the tracks of these retainers results in poor bearing retention and also in smoothless travel as it moves along the linear shaft.
They are individually sealed and boxed.
As with the use of all LM8UU bearings we would suggest have chamfered ends to your smooth rods to avoid displacing bearings when the smooth rods are inserted, or at the very least do it slowly keeping the two aligned properly. With the KG bearings displacement is less likely but can happen if car is not taken.