the Average Joes felt a need for an alternative. Because no supplier can match Andy Baker, we called on the next best one we could find.
We called Batman.
We will be running AM Rev 4 pulleys on our practice robot, and will switch back to those when we’ve proved their durability for the way we drive. The weight saved will be significant – a little under 5 lb.
How were these manufactured?
It looks as if they water jet cut the outer feature and used a CNC Mill for the inner lightening pattern.
(That is what it looks like to me.)
I’m also interested in how they were actually made.
I would say Wire EDM looks likely here. Either that or a well tuned 5 axis water jet (but I don’t think you can really expect that resolution and lack of taper at that thickness). Plus Wire EDM seems like a bit more of a Bruce Wayne style manufacturing process.
The fillets on the lightening were hand done for sure. (so maybe milling on those)
Regardless, great looking parts. Hopefully with the modifications to the plastic ones that AM came up with fix the issue for some of the other people having issues. I know my team had serious issues with the vex plastic mecanum wheels the first year they were released and before the inserts went to metal the year after.
We purchased our pulleys from Bracoflex and were more aggressive.
on the hogging out of material
http://wiki.team1640.com/index.php?title=File:DB12_160207-3.jpg
Ok, so Batman is really one of the Average Joes. He was guided by mentors from two of our sponsor companies.
The raw stock is 6061 Aluminum (McMaster 8974K86 or similar).
The fabrication steps were (1) cut blanks, (2) NC lathe for through bore and center groove, (3) NC mill for fixture holes, (4) wire EDM tooth pattern, (5) back to NC mill for spokes/slots, team markings, and bearing pockets, (6) tumble parts in appropriate media to remove sharp edges.
Steps 1-5 above were done at one sponsor and step 6 at the other. Batman and other students have gotten quite an education from this. They did the CAD but are not qualified to use the tools above, so it was “watch and learn”, while their mentors showed off some skills.
In twenty years as an FRC mentor, this is the only time I have encouraged making custom billet wheels. And they look really cool; however, that is not sufficient reason (IMHO) to do something like this. As explained earlier (OP text), our goal was risk mitigation.
How long was the turnaround time on a part like this? Seems like a lengthy process.
Because our sponsors are represented on the team by very active mentors, willing to work nights and weekends, our turnaround was fairly fast. From completed CAD to the parts you see was about a week. Another factor to consider is the lost man-hours in our own shop, since (unlike Andy Baker) the team members involved cannot be in two places simultaneously.
That is an exceptionally average looking sprocket you have there Man Who Dresses Like a Bat.
Beautiful. I mentioned the desire for some of these to be sold on the Rhino thread but that was not on the table. What was the cost of the time/tooling and time commitment to build these?
I look forward to seeing those in action tomorrow. 
