Wednesday, January 21, 2015

MendelMax3 - Z Stepper Mount Flex - Part 2

After discovering the flex in my Z axis, I decided to see whether the flex was present just by moving the X-axis. I wrote the following snippet of gcode:
G28 X0
G1 X250 F3600
G1 X10  F3600
...repeat the above 2 lines 10 more times...
and this is what I saw (with the original MTW mounts):


I decided to design a brace, which looks like this:


It's designed to fit under the existing mounting plate:


And installs like this:


Now I get virtually no deflection:


About a day after I designed this, the MTW folks came up with a much simpler, easier/faster to print version:



These perform almost as good as mine, but are easier to install. Here's a video showing the deflection while moving the X gantry back and forth (sorry - it's slightly blurry):

I decided to use the MTW version due to end switch interference with my mount.

To summarize:
  • 0.1mm deflection using the MTW mount that came with the printer.
  • 0.03mm deflection  using the modified OpenBuild mount.
  • 0.01mm deflection using the MTW mount with the printed MTW braces.
  • 0.005mm deflection using the MTW mount with my heavy duty brace.
The MTW braces are available here.

My heavy duty brace is available here. I don't recommend using this because it has some fit problems (it interferes with the Z end stop).