LulzBot TAZ 4, User Manual

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2.9. TROUBLESHOOTING
2.9 Troubleshooting
Z Wobble
Undulations in the walls of a print may be due to wobble in the Z axis.
A thorough analysis of the potential causes is given by whosawhatsis
20
in
his article ”Taxonomy of Z axis artifacts in extrusion-based 3d printing”
21
,
however one point of particular interest for users of Slic3r is the wobble
caused by motor steps not matching the pitch of the Z rods thread. This
can be addressed by ensuring the
Layer Height
setting is a multiple of the
full step length.
The relevant part of the above paper is quoted here:
To avoid Z ribbing, you should always choose a layer height
that is a multiple of your full-step length. To calculate the full-
step length for the screws you’re using, take the pitch of your
screws (I recommend M6, with a pitch of 1mm) and divide by
the number of full-steps per rotation on your motors (usually
200). Microsteps are not reliably accurate enough, so ignore
them for this calculation (though using microstepping will still
make them smoother and quieter). For my recommended M6
screws, this comes out to 5 microns. It’s 4 microns for the M5
screws used by the i3, and 6.25 microns for the M8 screws used
by most other repraps. A layer height of 200 microns (.2mm),
for example, will work with any of these because 200 = 6.25 *
32 = 5 * 40 = 4 * 50.
20
http://goo.gl/iOYoK
21
http://goo.gl/ci9Gz
93
PROOF