pic: Speedy

[Donut]

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[lukevanoort]

That is one densely packed Vex 'bot! One question though, why are there PWMs sticking out of the top?

[Rohith Surampudi]

ok, 2 things
Firstly...WOW
Secondly,did you take the time to figure out the gear ratio

[Nuttyman54]

Originally Posted by Rohith Surampudi

ok, 2 things
Firstly...WOW
Secondly,did you take the time to figure out the gear ratio

He must have, if he can tell us the theoretical speeds...
I'm guessing the PWMs out the top are to be connected to the missing controller

[JC-75]

Thats Amazing, Good Job

[travis48elite]

One word descirbes that "WOW", that is something I have never seen done to the vex kits.

[anna~marie]

*agrees with the wow's*
Is it topheavy?

[Alex Cormier]

amazing man, amazing! Great design and all. How many metal, chain and gear kits does that comprise of? I can't wait to see more of your designs in the future.

[Rohith Surampudi]

30 boxes of krispy kreme Doughnuts to anyone whose team replicates this with scale proportions(must be built as close to the maximum size constraints as possible) as their 2007 robot

[Donut]

Thanks for all the compliments everyone! This is my second attempt at a Vex bot, the first was designed as a mini for this year's game.

The PWMs are indeed sticking out due to a missing controller. When I was working on the bottom I didn't want them to sit underneath the metal (since it was on its side for bottom work), so they are all twist tied to the top to keep them out of the way.

It has a number of gearings to transfer the power, but overall it has a 2:3 gear ratio in low gear and a 2:15 gear ratio in high gear.

I am worried about it being top heavy since there are 6 motors attached to the top layer, but with a battery and controller on the bottom I think it will balance out okay.

It uses up gears from the standard kit and one expansion gear kit (2 12-tooths, 8 36-tooths, and 6 60-tooths). It uses two chain kits though; I think you could get enough sprockets from one, but it uses so much chain that I only had 2 inches of chain left from both kits combined (this after moving the encoders closer to one side so I had enough chain). It uses 2 metal kits, but if you're willing to cut many of the long pieces and shafts to length it could easily be done with 1.

Speedy is 9" L, 11" W, and 8.5" H, if anyone wants to try You'd have really big encoders doing that...

[Bill_Hancoc]

Originally Posted by Rohith Surampudi

30 boxes of krispy kreme Doughnuts to anyone whose team replicates this with scale proportions(must be built as close to the maximum size constraints as possible) as their 2007 robot

I that possible with the weight constraint???

[artdutra04]

Very cool - I like it! Once this is done, I would love to see video of it shifting from low gear to high gear.

Just don't forget about gear train efficiencies. It looks like there are eight gear/chain reductions per side, and all those losses can all really add up. Each Vex gear reduction will only be about 90-95% efficient, while each Vex chain reduction will be about 95% efficient.

[i_am_Doug]

Originally Posted by Bill_Hancoc

I that possible with the weight constraint???

It would be about 20 pounds over weight if you even shaved the hell out of the gears. I think alumainium chain would be in order;or perhaps a belt thinking about this makes my brain tickle!

[Kyle Love]

Im betting that when it takes off it flips backwards. Use the metal struts as anti-tipping bars...they work great.

[Donut]

I'm willing to bet if you made the gears out of plastic still, you might be able to make an FRC bot like this. But if they're metal... those gears would be HUGE.

I am extremely worried about efficiency of the transmissions killing the motor power on this. There are 4 reductions from the closest motor to the first wheel, but there's an extra reduction added for each motor, and another for the omni-wheel (the vex encoder's just thrown on the end, I don't think that takes much power to run).

I just attached the radio, controller, and battery pack tonight. The battery pack is attached to the bottom because it lowers the CG tremendously and I had no where else to put it. It leaves me with slightly under 1/2" of ground clearance though, so no off-roading excursions are planned for Speedy.