This has completely eliminated any and all z wobble on my machine but in order to get this all working correctly it will take a bit of patience and effort beyond just printing everything and installing it. First a spring has to be installed from the harbor freight spring kit that is pictured but it will need to be trimmed down in small sections to get the correct lift off of the sliders. Too little and the carriage will bounce. Too much and there will be excessive friction and the sliders will not function properly and you will retain some z wobble.
The springs are only there to take the weight off of the sliders. You will notice the part that bolts to the lead screw move side to side more after this has been done. The heavy side with the motor has more movement than it ever did on mine without the springs and before the springs were installed that side never seemed to move. This can completely eliminate z wobble if done properly or it did for me anyways.
Once I had this done I noticed some ghosting. This was because the support that came from the lead screws before was now gone after completing the previous steps and emphasizing the play I already had in my z axis bearings so I printed the bearings listed in the included files for the z axis. This also takes some trial and error because it needs to slide freely without any play. To prevent binding I sized my bearings where there was only zero tolerance on the part of the bearing that is first printed on the print bed. The first couple of layers are always a little expanded or tighter than the rest of the print. Make sure these ends go on the outside or on the top and bottom of the z axis carriages.
For now I have only installed one of these on each side. I put them on the bottom on both sides and left the factory roller bearings sticking up a little less than an inch on each side to allow room for the printed bearings. If you cant afford to lose an inch of z height install two printed bearings per side. Zero tolerance ends facing out.
When printing these the rest of the bearing should still be a little tighter than igus bearings or standard bearings. I believe there should still be a little play in these to prevent binding. I never experienced binding with these because once I got to a point where I felt like it would work I stopped. The printed bearings can be adjusted by adjusting flow. Another step that must be taken with these bearings is to wrap some electrical tape around the outside of them to eliminate play between the bearing housings and the outside of the bearings. This also takes some trial and error to determine how much tape to apply. I used abs for the bearings and so far I am very impressed with them. I even like them better than my over priced igus bearings.
I actually performed this printed bearing treatment to every bearing location on the machine. I also used the included lead screw braces with the 608 bearings. I have tried this both ways and this seems to work better with these braces installed. Pls msg or comment any questions,tks.
Sand the top of the lead screw bracket and the slider that faces the lead screw bracket. The less friction between these two pieces the better. I sanded mine down to an 800 grit surface. This may not be necessary but it is definitely recommended.
Also I would suggest trying this first before changing out your bearings. Your machine may not experience what mine did with the ghosting.