Custom Vs. COTS Transmissions

[Matt Goelz]

In my opinion, COTS are better overall until you want your drive to do special tricks. For example, the inclusion of P.T.O.s and neutral gears of 254s and 1114s gearboxes in 2010 to drive their hanger was brilliant. That is one of very few specail cases where I would value custom gearboxes over COTS. Just for the timing of the build season, I would still expect many of the individual parts in custom gearboxes like those to be COTS to save time.

[Mr. Van]

Originally Posted by Mk.32

I just designed custom gearboxes for a WCD we are hopefully going to build.

We need to be careful here... If you have actually "designed" the gearbox, you need to publish the design in a "public forum" in order to legally use it for the competition. (This is assuming that the same rules apply as last year... which may change, but probably not.)

The rule of not using custom designs over again is certainly the most violated in FRC. Many teams use the same designs over and over again without understanding that they are not following the rules.

The best part is that many teams have begun to publish their designs with complete drawings and specifications. This goes for both parts and software. THANK YOU to those teams who have been sharing their success!

- Mr. Van
Coach, Robodox

[Cory]

Originally Posted by Mr. Van

We need to be careful here... If you have actually "designed" the gearbox, you need to publish the design in a "public forum" in order to legally use it for the competition. (This is assuming that the same rules apply as last year... which may change, but probably not.)

The rule of not using custom designs over again is certainly the most violated in FRC. Many teams use the same designs over and over again without understanding that they are not following the rules.

The best part is that many teams have begun to publish their designs with complete drawings and specifications. This goes for both parts and software. THANK YOU to those teams who have been sharing their success!

- Mr. Van
Coach, Robodox

I disagree. How many teams use the exact same design with zero changes? I would bet zero or very near to it. Plus the way you interpret the rule is very misleading. You can certainly use something designed outside of the build season without making a single change to it...you just have to redraw it all during build to technically satisfy the rule.

Maybe the casual observer would think it's exactly the same, but if you change anything, you alter it such that it's an acceptable usage.

Our bases often look nearly identical, but there are constantly small changes to gear ratios, sideplates, shaft lengths, wheelbase length, etc.

[JesseK]

This year, we're going to do a custom gearbox ... somewhere, but not on the drive train. We've been mucking around with 1-1/8" hole cutting for a few weeks now, getting them correctly positioned and straight. In the end, I think we'll use custom gearboxes for a small wrist, a conveyor, or roller intake of some sort.

These systems do have a good argument for attempting custom gearboxes:
Those types of robot systems seem to need the most compactness of any robotic system, and often modifying COTS to can be more difficult or time consuming than designing the gearbox from scratch. With a custom gearbox it's easy to control mounting points and which side of the gearbox the output shaft is on -- with COTS, modifications have to be made to get the same effects. If the manufacturing of the mods goes wrong, new parts have to be ordered -- eliminating any time/headache saved by modifying COTS to begin with.

On another note -- The black FP gearboxes come with very forgiving plastic gears that have giant teeth. While they're probably not great for high-precision or high-power systems, they do seen to find their way onto some very successful robots every year. Hopefully they'll be in the kit again this year so they're legal to use.

[Ether]

Originally Posted by JesseK

On another note -- The black FP gearboxes come with very forgiving plastic gears that have giant teeth. While they're probably not great for high-precision or high-power systems, they do seen to find their way onto some very successful robots every year. Hopefully they'll be in the kit again this year so they're legal to use.

If it's legal to use DeWalt gearboxes (not in the KoP) wouldn't it be legal to use the FP gearboxes even if they're not in the KoP?

[Cuog]

I would consider what the students will get out of a Custom vs COTS Transmission. If one were on a team that had all the resources available(time, materials, tools) and some team members looking for a new design/fabrication challenge, I think a custom transmission would be a great project even if there were a perfectly suitable COTS one available.

[PAR_WIG1350]

Originally Posted by JesseK

On another note -- The black FP gearboxes come with very forgiving plastic gears that have giant teeth. While they're probably not great for high-precision or high-power systems, they do seen to find their way onto some very successful robots every year. Hopefully they'll be in the kit again this year so they're legal to use.

These are an excellent choice for the Banebots RS-775 motors since they already have the appropriate mounting holes for a 700 sized motor and the plastic gears and mounting holes electrically isolate the motor from anything else a short in the 775 could could interfere with.