DropLit Assembly Guide
Now you need to install the two M3 grub screws into the 5mm shaft coupler before you can
install it on to the stepper motor.
Using the included Allen wrench, thread one of the grub screws
into the side of the shaft coupler as shown. The stepper motor
included with the DropLit has a “flatted” shaft. You want to slide the
shaft coupler on to the stepper motor's output shaft such that the grub
screw you just installed will grip on that flatted portion when it's
tightened down.
When the shaft coupler has an internal feature
that will limit how far down the shaft it will travel.
Once you reach that spot, tighten down the grub
screw.
Rotate the shaft coupler a bit and install & tighten
the second grub screw as shown below.
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Fig. 5-3: Shaft coupler prep.
Fig. 5-4: Flatted Shaft.
Fig. 5-5: First grub screw tightened.
Fig. 5-6: Last grub screw in.