Poofs Gearbox of Doom

I was looking at some of my photos from Atlanta and I found this:


I had a couple of questions:

-How were you able to get your parts Anodized and was it expensive?
-Where did you get the gears from?
-Where did the 7068 aluminum come from?

Great gearbox, absolutely amazing. I had another question, would it be worth it to add another motor to any gearbox to give it more torque and pushing power. Maybe a fisher price??? I was planning on making a really light two speed gearbox and a crazy four speed, only using the four speed if the game requires three or four speeds and to show off in the offseason (almost done with it).

If I remember correctly, the gears were hobbed out of CNCed gear blanks. 968/254 used AM gears this year because they were much easier and consumed less time.

This is all in the archives. You will be able to find out most of the information about this transmission if you search.

I looked and if anyone could provide a link I would be really greatful

This Ultra-Lightweight gearbox was the undergraduate senior project of manufacturing engineers Travis Covington and Kirk Oden at California State Polytechnic University. They are the experts on it, but I’ll explain as best as I can.

The gears all started life as several-foot lengths of 7075 and 7068 bar stock, obtained from a local supplier. Dozens, perhaps hundreds of hours went into their fabrication: slicing and machining blanks, hobbing teeth, pocketing for weight, etc. The hard annodizing with Teflon impregnation was a proprietary process done at a local sponsor. It achieved a surface hardness of approximately Rockwell 50 C.

This year, we designed a similar gearbox (using steel gears) which included the Fisher Price motor as well. The difference was substantial. However, we eventually removed the Fisher Price from the drivetrain in order to use in the elevator, and moved the Banebots 550 (previously in the elevator) to the roller.

In two previous years we competed with a 4 speed transmission. While it was neat, we did not find it terribly useful in the rather small playing field (especially given the increase in cost and fabrication time).

We now try to use as many AndyMark gears as possible to save time and money. We still use some Martin gears when we can’t make the design work with the tooth counts AndyMark stocks.

Here are a couple of links on 4-speed stuff that Jim Z. did. The killer bees used a 4 speed before I joined the team. It helps in an underpowered machine. If you are throwing 4 cims in the drivetrain or more, there seem to little actual benefits (as you already pointed out) other than the WOW factor.

4-speed tutorial:

4-speed calculator

I cannot stress how impressed I was with that ultralight gearbox. Very cool. When I looked at it at the Championship, I was starting to notice some spalling on the gear teeth. How long did the anodizing last on your machine? Was that a service part, or did it last through a season, 2xseason, still running same parts today…?

There was an initial wear-in period in the anodizing. Nearly all the wear you saw occurred in the first few cycles. We ran an accelerated test platform which ran the gearbox for several hours in full speed forward to immediate full speed reverse cycles, in both gears, and experienced no significant wear on that platform after the initial wear-in period. Additionally, the competition robots exhibited no failures or significant wear over several competitions, and likewise with the practice robots after probably over 100 hours of use. These aluminum gears are actually stronger and harder than off-the-shelf steel gears (such as Martin) you can buy.

Here is where the picture was originally posted: http://www.chiefdelphi.com/media/photos/28070
That thread contains a link to this thread: http://www.chiefdelphi.com/forums/showthread.php?t=54420