Re: Minibot climb rate
 

You're right, the update only says motor and battery are required; it doesn't say controller although it says "appropriate circuitry", so what would that be other than through the controller? You can't follow the robot electrical rules and direct wire it because that would require the power panel and fuses which aren't on the allowable material list. So I still need those weights.

Re: Minibot climb rate
 

My impression is that the ROBOT electrical rules don't apply to the MINIBOT. It has its own rules. This appears to another case of confusion with when the manual should say ROBOT and when it should say HOSTBOT.

I expect great things from the Q&A. Terrible, yes, but great.

Re: Minibot climb rate
 

The first prototype was pretty flimsy. We are looking adding some more structural support and are assuming the Tetrix DC motors and battery are heavier. Once the design is optimized, we'll go through and lighten it up. We're 90% sure now that we'll build our own frame out of aluminum and not use the Tetrix materials. Hard to plan this out without the components (motor and battery). It is sad that they didn't put those in the KOP.

I'm even more convinced now, that the real challenge with the minibot is your deployment system. I have a feeling that at competition, we'll see some great minibots, but not as many great deployment systems.

Re: Minibot climb rate
 

Re: Minibot climb rate
 

Correct me if I am wrong but isn't it possible to use the Tetrix continuous rotation servos in addition to (or instead of) the allowed motors per rule <R92> A?

Re: Minibot climb rate
 

Where do you order these kits. We have never done anything with FTC. It is a stretch for us to do FRC. This is a challenge we have. Where do I order the 2010 FTC Base Kit. I looked on line but all are Back ordered. Where have you bought these from. Thanks

Re: Minibot climb rate
 

For the original question:

Last night we weighed 2 minibot motors, 2 minibot motor mounts, the FTC battery, 1 TETRIX 18" Rail, and (2) 4" wheels. Total weight was between 4 & 4.5 lbs (scale only does 0.5-lb increments, but rounds up).

I will note that we do not plan to use the NXT or the motor controllers. We cannot find specs regarding the NXT's shock rating. Without that data, and given the open-field nature of this year's game, we will not put a $200 device on the bot and call it "reliable".

Re: Minibot climb rate
 

I just received my (free, with hundreds left in stock - I will not be providing details [again] - search for it - I feel like Gary and Eric now) FIRST Choice FTC Mini Kit. Rushing (imagine me doing that) back to one of our labs, I measured the following weights for the FTC DC motor and battery pack:

Motor: 210.35 g
Battery Pack: 599.69 g

What are these strange Copiolian measurements of which I speak?

Motor: 0.464 lb.
Battery Pack: 1.322 lb.

Also, enclosed within my effectively-packaged AndyMark box was a sheet proclaiming a 30% discount on additional *in-stock* TETRIX parts for FRC teams via www.legoeducation.us/FRC. No blar comments from the peanut gallery - this is one thread that hasn't given me a headache yet.

Re: Minibot climb rate
 

ALL RIGHT! Travis is the go-to guy for FTC questions

A couple quick ones -

Weight of the wheels?

Thickness of the gears? (and weight, but I can calculate close enough)

Verify 32 diametral pitch on the gears (is the 120 tooth gear 3.75 PD?)

Thanks

Re: Minibot climb rate
 

Travis is surely not the only one with an FTC mini kit handy, as at least 800+ other teams have ordered these. ;)

Did you know that the gears were "Assembled in USA"? Probably the reason behind the cost.... Go go gadget globalization.

Mr. Ruler sez that the 120 tooth gear's PD is 3.75", and its thickness is 0.25"-ish.

Mr. Scale sez that the 120 tooth gear weighs 114.71 g / 0.25 lb. (in its thin plastic packaging - didn't want to mess up the shiny finish).

Mr. Scale also sez that the 4" wheel weighs 117.24 g / 0.26 lb.

Re: Minibot climb rate
 

The gears are .25" thick. They do have a diametral pitch of 32.

They have a bore of 8mm with four 3.5mm holes on a 16mm bolt circle. There are also eight 8mm holes on a ~59.58mm bolt circle. I think these are decorative. :)

I can corroborate Travis' weight measurements.

Re: Minibot climb rate
 

Did you get a weight on the 80 tooth gear? Or would I be close enough by extrapolating it from the 120 tooth?

By extrapolation I'm guessing the 80 tooth gear is 76.47 g.

Re: Minibot climb rate
 

I'm not in a position to do any more measurements today. Perhaps another can help out with additional measurements?

Is your math right? Gears are same thickness and have the same number/size of holes.

120T area = pi * ([120/32] / 2) ^ 2 = 11.045 sq. in.
80T area = pi * ([80/32] / 2) ^ 2 = 4.91 sq. in.

Density Ratio = 0.444

80T Weight estimate = 0.444 * 114.71 = 50.93 g

Re: Minibot climb rate
 

Interesting, but <R92>B states No more than seems to exclude a third motor.

(Team Update 1 changed A to read "A. TETRIX components that are not in violation of any other rules", and B is an other rule)

Re: Minibot climb rate
 

A computer is nothing more than an arrangement of switches. It can be mathematically proven that if you properly arrange switches, you can build memories, arithmetic logic units, registers, and many more things needed to build a modern computer. That is why you see binary, or base 2 arithmetic in computers. It is their native language.

From the robot rules - "An unlimited number of limit switches and two ordinary household light switches." is allowed on the minibot.

So it is possible to create a "computer" that has a hardwired program to perform the necessary algorithms for machine control. After all Von Neumann said that hardware and software was equivalent ! Really.. He did !

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