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

[de_]

I still can't figure out how those super fast robots are doing it. The rules give you 3 alum. gears but none of them look big enough to have the 120t gear in use. There is some talk of bypassing 2 gears in the motor gearbox but that sure looks questionably legal.

Also, what are they using for traction material on the output shafts (like 118) ? (Electrical) Heat Shrink ? Surely there is no "hard" surgical tubing ?

[Joe G.]

Removing/modifying the attached gearbox is perfectly legal. When removed, the motors spin far too fast to allow "normal" wheels. But with small diameter shafts used to climb the post, torque output is dramatically increased. Most of these smaller shafts seem covered in heat-shrink tubing, or surgical tubing.

[DonRotolo]

Try this: Remove the gearbox entirely. Drill a tetrix shaft with a #40 drill (0.098) in exactly the center and press it on to the motor shaft. Cover the tetrix shaft with latex tubing (hint: rubbing alcohol makes a fine lubricant to slide it on). Support the far end of the shaft (tetrix bronze bushing).

Two of these motor/shafts, a battery, 2 switches, and a clip or magnet to hold it on and up you go in (how many?) seconds.

[Grim Tuesday]

If you don't have any rubbing alcohol on hand, warm water works just as well.

Where the experimentation and design comes in is where to put the motors:

I've seen ones with two motors on one shaft, two motors clamping onto the pole, and one with one motor on top and bottom.

I'm not going to tell you which was fastest

[AndyH]

Originally Posted by DonRotolo

Try this: Remove the gearbox entirely. Drill a tetrix shaft with a #40 drill (0.098) in exactly the center and press it on to the motor shaft. Cover the tetrix shaft with latex tubing (hint: rubbing alcohol makes a fine lubricant to slide it on). Support the far end of the shaft (tetrix bronze bushing).

Two of these motor/shafts, a battery, 2 switches, and a clip or magnet to hold it on and up you go in (how many?) seconds.

That is more or less what we did. It is super light and very fast.

[Chris is me]

Tetrix shafts are too small, go bigger.

[Aren_Hill]

Originally Posted by Chris is me

Tetrix shafts are too small, go bigger.

whatever you say chris , depends on the surgical tubing size and the minibot weight

[PAR_WIG1350]

Originally Posted by Chris is me

Tetrix shafts are too small, go bigger.

less is more when it comes to output diameter and force.

[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.

[Chris is me]

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.

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.

[davidthefat]

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.

Thank God. I don't know, our mentor, team captain and anyone with "authority" blantantly said "no David, no". Now for LA we are just making our MB super fast. Honestly though, we had a very very reliable deployment and minibot. (11:15 made to attempted ratio) It was slow, but that got us to Semi Finals and apparently we ended the competition at rank #4. I am impressed.

[Chris is me]

A slow minibot that makes it every match made our #6 spot on our pick list (maybe a little lower, I don't have it). It's all about consistency.

[WizenedEE]

Is very, very reliable 11:15? Less than half?

We haven't gone to an actual competition yet, but we've never failed in deploying - obviously, it will be different with all of the other robots flying everywhere, but still. What was yours like during testing?

[davidthefat]

Originally Posted by WizenedEE

Is very, very reliable 11:15? Less than half?

We haven't gone to an actual competition yet, but we've never failed in deploying - obviously, it will be different with all of the other robots flying everywhere, but still. What was yours like during testing?

Honestly, it was fail proof, but not human proof. It is programmed that the robot backs up into the pole as it deploys so it is guarantee that it deploys. The 4 were human errors such as forgetting to put the deadman switch on or driving away from the pole as it deployed or going to the pole too late(we just get pushed around) But it makes it every single time as long as we set up around 25 sec. But we did not choose to use the arm (we zip tied it to the robot), so we went defensive (because of our design flaw, that was our down fall) then deploy every match.

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


Edit: that minibot alone got us to the #3 spot (we dropped down to #4 when we DQed for getting pushed into the scoring zone by the other robots several times at the semis)

[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.