Minibot climb rate

[Tobot]

We are flirting with 3.5 second climbs on a fresh battery.

http://www.flickr.com/photos/ukweli/5466703933/

[Gary Dillard]

Originally Posted by Jared341

That is exactly what we did (using only an inexpensive mill and lathe and a dremel), and it works great.

We were able to modify the Tetrix gearbox with no special tools / machines - we just had to stake the ID of the large gear to get it to press on to the top of the output shaft at the position of the gear attached to the brass gear

[wireties]

Originally Posted by Gary Dillard

We were able to modify the Tetrix gearbox with no special tools / machines - we just had to stake the ID of the large gear to get it to press on to the top of the output shaft at the position of the gear attached to the brass gear

What was the resulting gear ratio? And what does "stake the ID mean"?

TIA

[Mr V]

Originally Posted by wireties

What was the resulting gear ratio? And what does "stake the ID mean"?

TIA

If you look at the output shaft you'll see that in the area where the gear is pressed on the shaft is "knurled" or has ridges formed in it to create the press fit. So I assume he means that they used a chisel or punch to deform (stake) the ID (inside diameter) of the gear so it will press on the un-knurled portion of the shaft where it will mesh with the input gear.



The mod of making the first gear mesh with the gear on the output shaft results in a 10.4 to 1 ratio instead of the factory 52 to 1.

Another way to accomplish this IF you have a lathe is to machine a spacer that fits on the output shaft between the gear and case so that it meshes with the input gear. On the motor end of the output shaft you need to turn it down the same amount as the length of the spacer so it will fit in the case.

In addition to increasing the output speed ~5x it reduces the drag in the trans aprox 50% by removing 2 gear interfaces. Make sure you don't loose the spacer on top of the input gear and remove the spacers on the other shaft, there is a small one on the shaft under the 25:10 gear.

[Grim Tuesday]

Why keep that silly gearbox? Take it all the way off, and you can be seeing times in the 1.4-1.8 range. Most of the gains are due to the loss of weight of the huge wheels, and the gearboxes, not the raising of efficiency.

[pfreivald]

Originally Posted by Grim Tuesday

Most of the gains are due to the loss of weight of the huge wheels, and the gearboxes, not the raising of efficiency.

That is fundamentally untrue, and easy to demonstrate as untrue.

Our current minibot is in the 1.8 second range (and very consistent, thank you), and even when we add excess weight just to see what it does with it, it's still faster.

Reducing weight matters, but increasing efficiency matters a whole lot, too. It's not a dichotomy, here -- both are important!

[Grim Tuesday]

Thanks for proving me wrong. I was just inferring, so apologies, and I learned something!

[billbo911]

I know it's not fast, but it's reliable. We are thrilled it is ready for Sacramento.
http://www.youtube.com/watch?v=AVx7oFAyfjg

[ngoc0623]

in order to climb the pole, you dont need the wheels and with this you can cut the weight of the minibot. Just suggesting.

[jskene]

We were consistently getting ~1.2 seconds. We got our minibot measured by team 1279 at the DC regional and got a higher accuracy measurement:



Our deployment arm, when it was working properly , was taking ~0.2 seconds to get the bot on the pole, so total time was ~1.27 seconds.

Below is a photo of the bot, which uses a cnc machined chassis. Our goal was to use only the minimum of materials necessary to hold the components in place. Weight came in at 2.5 lb.

[WileyB-J]

meet richard.

not the fastest liger in the forest but hes around 2.2s and stupidly reliable.
it seems like its one of the most machined minibots out there!

[theschell]

our mini bot helped us get up the pole in under 2 seconds with deployment so that got us back to back wins

[EagleEngineer]

I know 968's minibot is exteremly fast. They get like .7 seconds with the dployment. Well that is what was said, but if you saw it in really time their minbot was up when the clock still said 9. This minibot helped them win the LA regional. their minibots somewhere around a one seconds minibot.

[Marc S.]

Originally Posted by jskene

We were consistently getting ~1.2 seconds. We got our minibot measured by team 1279 at the DC regional and got a higher accuracy measurement:



Our deployment arm, when it was working properly , was taking ~0.2 seconds to get the bot on the pole, so total time was ~1.27 seconds.

Below is a photo of the bot, which uses a cnc machined chassis. Our goal was to use only the minimum of materials necessary to hold the components in place. Weight came in at 2.5 lb.

Thats prety impressive. If you don't mind, what roller size did you use?

[jskene]

The axles are 3/8" aluminum, drilled to fit the motor shaft (we removed the spiral gear). The "tires" are 1/2" OD surgical tubing.