Almost any Cantilever Z axis will have a little bend at the open end if you push hard enough. the trick is to make that bending motion take enough force that your extruder can't push that hard during normal printing. You also need to make sure that what vibration it DOES have damps out quickly and does not have a resonant frequency in your printers range of vibration. Since the linear guides can attach every 15cm to the wall, you have essentially ZERO side to side motion, and the UP and DOWN vibration does not vary with the height of the bed like it will with round linear rods. In my case I initially only attached each rail with 3 screws which was not much improvement over linear rods held at the ends. The video was taken while I had only 3 screws and was reduced a lot later by adding more mounting screws.
In my case, now I only see bending if my print head runs over an area that overextrudes many layers in a row, or if I got a weird blob. My prints were accurate enough pretty quickly and I soon did not have these problems, but in the video, it was very early in my testing so my adjustment was not too far along AND I was printing at high speed with a lower acceleration and jerk rate which left more over-extrusion at the corners and direction change points in the print. AND i needed more mounting screws. BUT, as I said, my printer will still vibrate a little at the edge if my nozzle runs over an area of over-extrusion.
The reason why mine works so well was a combination of educated guess work and the vibration consistency provided by use of the linear guides.Frankly I got really lucky for a first try, and the only mistake I made was I initially only attached each rail with 3 screws which was not enough to stop the rail itself from vibrating. This was very easily solved by putting in more screws. I actually cheated a little and only put a screw in every other hole....
Edited 2 time(s). Last edit at 12/17/2015 11:39PM by patrickrio.
