Cetus Z axis clamp
Description
Improved design see: https://www.thingiverse.com/thing:3586841 Works much better than the original Cetus part. This clamp design incorporates more degrees of freedom to compensate for printer manufacturing tolerances which results in a more consistent clamping force. Equally important is this approach makes two threaded stepper holes free for a Z axis brace. The Z axis shakes whenever the extruder stepper motor is accelerated and the vibrations are frozen in the print surface. PLA makes a poor braking surface because friction causes heating and then the PLA becomes a lubricant which is followed by the Z axis crashing into the print bed. A strip of shim brass isolates minor PLA viscosity changes. Then the compression spring compensates for any minor PLA shifting from a layer hill to a layer valley. Print on fine with a 0.1mm layer thickness. Use a 0.4mm nozzle but choose a 0.3mm extrusion line width. The PLA is thin 0.6mm around the sprag clutch bearing to distribute the clamping force more uniformly over the bearing surface. You need a stiff spring with about 2 lbs force when compressed, a 4-40 or M2.4 nut and bolt, and a small strip of metal. I used 0.005 thick shim brass cut with scissors. I folded the end to double the thickness then poked a hole with a nail for the bolt to pass through to preventing the brass from shifting or rotating in the final assembly. In the photo the steel bracket firmly connects the Z stepper motor face to the printer base. Measuring deflection with a Dial indicator the top of the Z axis deflection is now 0.003" over the travel limits of the shifting extruder motor weight. The bracket also makes tramming the printer possible (make the three-axis perpendicular to each other) should you be so inclined. -Peter
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