@@ -81,3 +81,13 @@ This configuration almost works for both PCBs and wax, with dF/dz = 30 N/mm at s
- Better string, two strings, belt, leadscrew.
- Evaluate bearing design and improve if it makes sense to do so.
- Measure plate compliance (better word than stiffness?) and increase roller separation to stabilize if it makes sense.
### Evaluating and adding stiffness to z-axis.
#### Adding more string
- Confirmed about 30 N/mm stiffness on z axis at the spindle axis.
- Measured force and motion with a force sensor attaced to the plate that move the z-spindle, so that little torquing of the bearing was involved. The result is identical to the spindle measurement, about 30 N/mm, indicating that most of the axis compliance is associated with the belt and motor, rather than the rubber bearings.
- Braided three strands together. Upon reassembling, the stiffness increased by ~20 percent - not significant. I can see that the motor is turning slightly as force is applied. Looks like stepper motor torque is the limiting factor. I will reduce the motor spindle diameter by a factor of three or so.
