Next, I installed the three bearings that carry the axial
load of the scanner and mount. This is again a nice touch,
as many would likely have simply let the stepper motor
carry this load which would ultimately reduce its life and
maybe even result in more lost steps. The bearings are
affixed with machine screws.
The screws are installed with a 2. 5 mm hex wrench
(not included). Access to install and tighten them was
sparse, so I ended up using the short side of the key and
lots of small motions (Figure 6). A few extra access holes
would be nice, but I also understand not wanting any extra
holes in the enclosure from an aesthetic standpoint.
With the bearings in place, it was time to install the
micro switch that served as a homing/limit switch for the
device. I soldered the 10K resistor on the switch and the
associated jumper leads, then insulated the whole thing
with heat shrink tubing (Figure 7). The resistor in my kit
was quite large — maybe 1W or so — which seems
unnecessarily rated and larger than the one in the assembly
guide. It still fit into the enclosure and the switch was
secured with two screws (Figure 8). The switch arm
protrudes from an opening in the enclosure (Figure 9) and
is activated by an extrusion on the scanner tower.
Similarly, I installed the stepper motor, trimming and
tinning the leads, then securing it with two M3 screws
(Figure 10). The instructions indicate that cutting the leads
to about 100 mm is best, but I found those a bit short on
Figure 8: The micro-switch installs with two self-tapping screws.
Tucking the large resistor away was a bit of a challenge. Leaving
slightly more lead exposed out of the solder joint would have
made it easier.
Figure 9: Good enclosure design has the switch arm just protruding
out into the travel ring of the scanner tower. An extrusion on the
tower cleanly trips this switch for homing position information.
Figure 7: The contacts on the micro-switch either were not
labeled or labeled in a difficult-to-read engraving on the plastic.
Quick verification with the multimeter showed that this was the
Figure 10: The stepper motor installs with two M3 screws. Trim
and tin the leads before installation. I found leaving a little more
than the recommended lead length was helpful.
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