pic: Team 100 Prototype Base

[Andy Baker]

This looks great.

I really like these things:

1. The use of the 1x2 t-slot extrusion for tensioning the chain. This is simple, and it does need some attention at times, as t-slot nuts can move. However, if you add in an extra t-slot nut next to the ones that are attaching your hardware, it seems to be a more stable system. Give yourself plenty of adjustment room for chain stretching.

2. How you designed the live axles with the sprockets on one side and the wheels on the other is good. This is similar to other "west coast drive" designs, but your plan for t-slot tensioning is unique.

3. The simplicity of your bumper mounts is good. The problem with bumper mounts is that they get beaten up during the competitions. A designer needs to decide if they are to put the material (and therefore, weight) into the mount bracket to last through a season, OR to make a lightweight mount that can be easily replaced when squished a bit. If those are aluminum, they may be getting squished... but they also look easy to replace.

4. The frame you have made can easily contain most of your control system. I may suggest using perforated aluminum sheet, combined with two - 1/2" tube stiffeners as a floor for this base.

The only design change I would suggest would be with regard to the brackets that attach the sides to the front and back. You can easily make a long angled bracket on the bottom and keep the short bracket on the top. The bottom bracket won't get in the way of your electronics if it is longer, and it could also help hold up your floor. Also, if you make this piece longer, there is less force at each connection point during frame torsion and it would not need to be welded into place... fasteners would work.

As for the middle wheel height, dropping that center wheel down 1/8" is about right. I've used 0.15" and that seems to work well also. Another way to monitor this is to keep new treads on the middle wheels. I've also seen teams that make their outer wheels have a bit less of a diameter, and that effectively does the same thing as dropping the middle wheel. The wheel speeds are slightly different, but that is negligible in this application.

Best of luck with this. It looks outstanding.

Also, congrats on having the guts to post this design... putting it out here for people to comment on takes courage.

Andy Baker

ps... thank you for designing in AndyMark products.