The New Method-- Motor shafts
are LEGOized by attaching a LEGO axle adapter: a 1-unit long piece of axle
that has a hole drilled into it to fit the motor shaft. The procedure is:
- Select the correct adapter.
Different motors have different size shafts and require different adapters.
Be sure you have the correct one; ask a labbie.
- Clean the motor shaft. If
it is new and knurled, just wipe it with some alcohol. If it smooth, or
has had glue or shrink tubing on it, sand it lightly with fine sandpaper
to get it really clean. Hold the motor shaft down to avoid getting grit
in the bearing! Then wipe clean with alcohol. Clean is good.
- Apply glue to the end of
the shaft. Use Locktite 409 instant adhesive (super glue gel) or epoxy
to just the end of the shaft, about 1/4 inch, all around the circumference.
Keep glue away from the motor bearing!
- Push the adapter onto the
shaft. The idea is to push the adapter on the shaft just enough so it
will clear the the thickness of a LEGO beam. This will avoid friction between
the adapter and the beam. (For plate-mounted motors, substitute plate
for beam below.)
- Have your partner hold the
- Put a LEGO beam over the
shaft, so the shaft goes through a beam hole, and the beam is flat on
the motor bushing.
- Hold the adapter with pliers,
and put it on the shaft; you may need to tap it lightly.
- Push/tap the adapter down
until the base just touches the beam surface. See the picture at left
to see the spacing. (For visibility, the shaft does not go through the
beam in this picture.)
- Double check that there
is no glue near the motor bearing.
- Let the glue set. A minute
or so for Locktite, 10 minutes or so for epoxy.
- Ready to use! Since the
adapter fits through a beam hole, you can remove the beam used for spacing,
and mount the motor as needed on a beam, etc., then add the gear of your
Reference Information for Making
|Johnson Flat Sides
Johnson 31348 Johnson 30029
|Johnson 3520 (old)
The holes must be on center, especially
the #42 drill, to avoid broaching through the side of the axle. This requires
a precision small drill press and an X-Y micrometer stage to position the
adapter (and good eyes or a magnifier). I hold a 2-long LEGO axle in a 40-tooth
gear bolted to the stage, drill through it, and then slice it in half using
a utility knife blade to make two adapters. Use two beams to hold the axle,
with the blade between the beams; whap the blade with a small hammer.