Originally Posted by sst.thad (Post 1089481)

If you look at the big blue box under R22 this year, it says that if designs are posted publicly they are allowed to be reused because they are considered cots parts

Originally Posted by Justin Montois (Post 1089514)

Thanks everyone for the input. It seems that the general consensus is that custom transmissions can help great teams dial in their designs more efficiently, but for the most part it's not giving them a significant advantage.

Now, most of the comments on here seem to be based around transmissions for drive bases. Does everyone have they same outlook for custom transmissions for arms, conveyors, elevators ETC? Still not worth it?

Originally Posted by Justin Montois (Post 1089514)

Now, most of the comments on here seem to be based around transmissions for drive bases. Does everyone have they same outlook for custom transmissions for arms, conveyors, elevators ETC? Still not worth it?

Originally Posted by thefro526 (Post 1089538)

We learned the hard way in 2011 that there's no 'easy' COTS solution for an arm transmission that requires a relatively high reduction. If we were to do it over again, we'd definitely build a custom box just so that we can avoid blowing half a dozen $70+ transmissions.

Originally Posted by Peter Matteson (Post 1089550)

Really? We went completly COTS by putting AM fischer-to-Cim planetery into a 3 stage AM stacker box with a single sprocket reduction on the output. This solution was quicker and easier than building a custom gearbox to get the same redction. The use of the planeteries also gave use a more compact footprint than we would have ever had with a spur gear based transmission.

Originally Posted by thefro526 (Post 1089551)

Our overall reduction was ~1228:1, so using a similar solution to yours would've required a 4th Stackerbox or a ~7:1 Reduction off of the Third Stacker Box. We also ran two 775's on our arm which made playing with COTS stuff a little difficult.

Originally Posted by Wayne TenBrink (Post 1089473)

This subject touches on my biggest pet peeve about FIRST rules: the prohibition, without exception, on re-use of fabricated components, existing designs, or modified COTS items. Transmissions are a great example, but the same principle applies to any number of other components & assemblies.

If we were to go to the effort and expense of developing and building our own transmission (a good thing), it would glorified scrap at the end of the season (bummer). If we just bought a COTS transmission and didn't modify it (normal business practice, but not as much of a learning experience), we would be free to re-use it in the future. This is a big disincentive against making anything you can buy. Perhaps FIRST could set some allowance for "legacy" fabricated parts - by weight, parts count, dollar value, etc.

If we were to invest in a pair of COTS shifting transmissions and then we drilled one new mounting hole in each (heaven forbid we deburred or lightened the gears) they would be unusable for future games. Perhaps FIRST could set some standards for minimum allowable modifications for re-use of COTS items - i.e., drilling holes, shortening motor shafts, etc.

I know that its easy to recycle a design by making some meaninglessly trivial modification, but that just encourages "gaming the system". Perhaps FIRST could allow re-use of designs that had been publicly posted.

I like the FRC supplier base that has developed in recent years, and we take advantage of it. However, when combined with existing FIRST rules, it creates some negative and unintended incentives. I hope FIRST will consider allowing limited re-use of legacy designs & hardware that teams creat or enhance with their own brains & hands.

Besides, the unique requirements for each game put a natural limit on the number and type of items that are worth re-cycling.

Originally Posted by Wayne TenBrink (Post 1091040)

I re-re-read the 2011 rules, and I concur that FIRST has approved the re-use of a publicly-posted design. That is certainly a good incentive to develop our own designs, and provides another resource for teams looking for new technical solutions.

PS - I have spent a lot of time over the past couple of weeks trying to design a gearbox. The experience has given me a deeper appreciation for the AM super shifter. The more you study it, the more you realize the elegance of the design.

Related comment and questions: All the gears in the super shifter transmit power to their respective shafts via a hex shaft (directly or indirectly via the shift dog) with the exception of the pinion on the intermediate shaft, which drives the larger gear on the final output shaft. It uses a square key. Has anybody had a problem with that key? One of the designs I am considering would require a square key on the input gear (that meshes with the pinions on the CIMs). Do you think that would work, or would it get loose over time/reversal of direction?