How are <1.5 sec Minibots doing it ? Gearbox mods allowed ?

[Bjenks548]

Originally Posted by davidthefat

Edit: that was not the gear ratio, I am saying reliability > speed. We had a 4 second minibot

Speed does play a huge factor once eliminations hit. We were on the number 5 alliance going against the number 1 alliance. We had one minibot, they had 2. The only way we could win was to get our minibot up first and let them score 2 and 3. We also had to outscore them on tubes. We beat them. While reliability is what gets you picked. Fast minibots get you a win.

[PAR_WIG1350]

Originally Posted by The Lucas

You can always modify any gearbox unless the rules (or Q&A) specifically states you cannot modify it because it is integral. Currently, the only legal modification you can make to the Denso window motor gearbox/motor is removing the pins (all other mods illegal, however you can do this). All other gear boxes are fair game for mods.

No, you cannot do that with a desno motor,
http://forums.usfirst.org/showthread.php?t=17054

however, the motor/gearbox combo photo is still legal due to this.

[de_]

Originally Posted by DonRotolo

Try this .... Cover the tetrix shaft with latex tubing ...

Thanks for the great insights.

I thought surgical tubing was rubber but maybe its latex ? Where do you find latex tubing with such a small inside hole diameter ?

What's the easiest way to provide enough pressure on the drive axles to get good contact with the pole. Is that where the magnets are used (presumidly close to but not contacting the pole) ? We used rubber band pressure on our traditional MB but it would be nice to simplify things.

Or is the magnet used on the perpendicular side of the minibot to hold it to the pole (again very close but not touching, perhaps held off by a roller beside it ?

[jtechau]

Originally Posted by davidthefat

Now this is where it confuses me, we purposely left our modified motors at our shop and used our unmodified minibot (got us really far) but apparently we had to sign a paper that stated we would not modify the gearbox. What was with that? I asked th inspectors, they said it was not allowed and said gracious professionalism should be kept. The inspectors never checked the minbots for modified gearboxes.

Originally Posted by Chris is me

This is blatantly incorrect. You are allowed to modify the gearboxes but not the motors. Anyone who said otherwise just doesn't know the rules.

The lesson to be learned here is that if you're doing anything that relies on interpretation of the rules or a Q&A clarification, make sure you do your homework, and bring a printout of the relevant rules / Q&A to show the inspector. In fact, make yourself familiar with all the rules. Be prepared to present the facts to the inspector; but don't try to argue with them - that will generally work against you. Remember gracious professionalism.

I recently had such a conversation with an inspector regarding the playing configuration size. He claimed that it included bumpers, which would not have worked for us. Fortunately, I was able to point out the rule section that clearly stated bumpers are not included in playing configuration size, and all was well.

[davidthefat]

Originally Posted by jtechau

The lesson to be learned here is that if you're doing anything that relies on interpretation of the rules or a Q&A clarification, make sure you do your homework, and bring a printout of the relevant rules / Q&A to show the inspector. In fact, make yourself familiar with all the rules. Be prepared to present the facts to the inspector; but don't try to argue with them - that will generally work against you. Remember gracious professionalism.

I recently had such a conversation with an inspector regarding the playing configuration size. He claimed that it included bumpers, which would not have worked for us. Fortunately, I was able to point out the rule section that clearly stated bumpers are not included in playing configuration size, and all was well.

Hello sir, we will see you at Long Beach. Good luck to you guys and be prepared. We will be prepared to dominate the West Coast.

[Gary Dillard]

Originally Posted by Chris is me

This is blatantly incorrect. You are allowed to modify the gearboxes but not the motors. Anyone who said otherwise just doesn't know the rules.

And I'm pretty sure that the GDC knows the rules

http://forums.usfirst.org/showthread.php?t=16779

[Free Willy]

Can someone post a picture of a modified gearbox? Thanks!

[Mr V]

Here is a pic of un-modified transmission.


The way you modify it to become a 10.4 to 1 can be achieved in a couple of ways. All of them involve removing the 30:15 and 25:10 gears and mating the 26:10 to the 40t output gear.

The way we did it was to machine a spacer that fits around the output shaft and raises it to the proper position to engage the 10t on the 26:10 gear. Then we machined the end of the output shaft you can see in the pic the same amount so the end plate fits back on with the proper end play.

A team we gave our spare minibot pieces to in Seattle knurled the output shaft so the 40t gear could be pressed up the corresponding amount. In the picture you can barely see the knurling on the output shaft where the 40t gear is pressed on.

I have also read on here of 2 other ways. #1 removing the gear and staking it around it's ID to reduce that diameter, then pressing it back on with thread locker as a little extra insurance. #2 shorten the case, and swap the existing spacers around, use the one that is under the 25:10 under the 26:10 and the one that came off the top of the 26:10 on top. This method also requires shortening the output shaft so the case fit's back together. This method is the most complex.

So there are a number of ways to skin this cat depending on the tooling and skills your team has.