Hey everybody,
I am a mentor with 470 and 66, now that our schools have combined, and this year 470 needed a gearbox for the PG-71 motor and we had the crazy idea to print one with our Cube printer we got through FIRST Choice. It was brought to my attention, at the Southfield District event, that this might be something other teams would find handy so I would like to give all of you access to this part.
Here is the link to the part. http://www.thingiverse.com/thing:267863
This part is meant to be used with the Andymark CIMple Box to allow the use of the PG style motors. We used the gear am-2088 with the motor and also had to machine a spacer that was about .220" long, .5" dia, with a .397" hole (Letter X drill) to keep the gear off of the face of the gearbox.
On the one we used on the robot we milled out a pocket where the motor shaft sticks through on the Andymark plate to allow for us to use a snap ring to retain the key. We made the holes, for the motor mount, a little loose to allow for small adjustments, to get the mesh of the gears correct, because of the plastic contracting when it cooled. We also found that sometimes when the part is printed it will mushroom the ends of the locator pins, so you may need to use a razor to clean them up so it fits nicely.
On the 66 robot we used the Vex Robotics Super Shifters and needed wheel spacers that were tighter than just a plastic sleeve. We found that creating a spacer the length you needed it with about a .020" spacing around the shaft and a wall thickness of about .100" worked really well for keeping a tight spacer. We also found that for lighter duty operations we were able to just download the andymark cad file and print different shaft hubs and use them.
I hope this information is helpful to all of you and your teams.
http://thingiverse-production.s3.amazonaws.com/renders/11/94/42/11/bc/3DParts03082014B2%2B012_preview_featured.jpg
http://thingiverse-production.s3.amazonaws.com/renders/52/4c/42/13/0a/3DParts03082014%2B016_preview_featured.jpg
