[diviney]

All:

OK, so we saw these really cool Andymark Nano Tube drive transmissions when they came out last year... We purchased a pair of the gear drive 3-shaft units in the fall with the intention of working on an off-season project. We never got around to this, and now that the season has begun, we are looking to use this as the basis for our drive. We are having some trouble in a couple areas that I would like to solicit opinions on.

First of all, the configuration of the Nano Tube makes it difficult to incorporate into an overall drive chassis with accommodations for bumpers all around. The fundamental problem is that the wheels stick out beyond the ends of the tubes. This means you can't just put a structural member across the front and back that's long enough to reach out to where the side bumpers need to go. The wheels interfere. If the tubes were maybe 4-5 inches longer (with the same wheelbase), it would be tremendously easier to incorporate into an overall frame. We will need to come up with some way to extend the tubes in order to have a structurally sound chassis.

Second (and worse)... These tubes are designed for 6WD, with an 1/8" drop on the center wheels. While trying to assemble them into a frame tonight, we found a vexing problem. The two Nano Tubes are identical (there is no left and right). A consequence of this is that an unavoidable asymmetry is introduced. If you arrange the tubes so both centers are "dropped", then the 2-wheel gearboxes are not directly across from each other ie: the front and center wheels are driven together on the left, and the rear and center wheels are driven together in the right. This will have an adverse affect on handling such that when the robot needs to push, it will not maintain a straight course.

What is really needed are two different styles (a left and a right) which Andy does not offer. We examined the possibility of reversing the components to create a mirrored version, but the features are not symmetrical and it would require a fair amount of machining to accomplish this.

Is there something obvious that we are overlooking here? We almost couldn't believe it when we saw this... If we wind up with Mecanum drive this is a non-issue because we will not use the center wheels (and we can presumably de-populate the center axles and gear train). We are just not seeing how to make this work as intended for a 6WD robot !!

Any thoughts would be appreciated.

-Tom