It’s a bit early in the process, but I couldn’t resist testing the fit for the motor mount using the AC-31 itself.  Since the motor mount was fabricated with the actual motor sight unseen (just blueprints) I wanted to make sure everything was ship-shape.

The motor mount consists of two parts: a face plate and a belly support.  The face plate bolts to the motor face with 4 bolts and then to the frame with two bolts.   It fits perfectly:

AC-31 test mounted in frame - right side view

Ideally, we’d have a matching plate for the rear end of the motor to support the weight, but since the AC-31 is so long it’s not practical to do so.  Instead, Kale fabricated a cradle shaped belly support that takes the weight of the motor (~100 lbs!).  The belly support bolts to the frame and the motor rests on top of the U-shaped cradle.  It’s just meant to support the weight of the motor, not prevent the motor from twisting around it’s axis (that’s what the face plate is for) so it’s not bolted to the motor.

The AC-31 test mounted with the motor face plate - left side view

Currently, the belly mount cradle is about 1/4″ too large in radius compared to the radius of the motor, but that’s because it’s going to have a 1/4″ thick rubber mat between the motor and the cradle to provide vibration damping.  I still need to buy that material, but it’s not expensive (about $5 for a 1′ x 4′ strip from Coastal Farm & Supply).

If you look closely at the left side view, you’ll see a bit of coat hanger wire tying the face plate to the frame.  That’s just there to keep the mount from moving since it’s not bolted to the frame yet.  It doesn’t make any sense for me to hard mount to the frame right now because I need the 1/4″ rubber mat for a proper fit and I’m going to be bench testing the motor & drive system anyway (which means taking the motor out completely).

I was a little concerned about the main electrical power connections being so close to the frame (this isn’t very obvious from the pictures) but Travis pointed out that the cables can be disconnected from the mount points provided so it should be okay.

Eric