Robot Parts and Materials - Answer Thread

[Sheldon]

Hello - we used a single pair of AM-2256 wheels last year which appear to be ruled out specifically by <R04.d>. Will other non-tetrix wheels need specific approval by the forum this year? We are currently planning to use AndyMark am-2611 tread on AndyMark 4" performance wheels. By our evaluation they do not appear to damage the field soft-tiles, but we wanted to check before we centered our design around them.

A: The GDC has not tested all possible tread and tire combinations and therefore cannot answer this specific question. During Mechanical Inspection teams may be asked to demonstrate that their choice of tread will not damage the tile floor during a match when (if) the bot is pushing hard against a wall or another bot and spinning it’s wheels. The test will be to place the robot against an immovable surface (wall) and run the wheels at full power for 15 seconds. If there is any physical damage to the floor tile then the wheels will not be allowed. Discoloration or black marks alone are not considered field damage. Remember, the test must be made with the robot at the weight the bot will be at during a match since this will affect the degree of damage.

[Sheldon]

As a followup to post #20 which states that there are no restriction on wheel diameters this season, can you tell us if we would be allowed to use either of these

http://www.servocity.com/html/precis...l#.VCMWBvldUfA
http://www.servocity.com/html/4_90__...l#.VCMWM_ldUfA

Thanks

A: The wheels in question are legal providing they do not violate Rule <R04d>. See Post 21 for explanation of how to test whether a tread/wheel is legal.

[Sheldon]

Is a fishing snap-swivel like this legal:
http://smile.amazon.com/Nsstar-Barre...wivels+fishing

A: Yes, this is a legal COTS.

[Sheldon]

Under rule R04 (c) I see that hinges are allow and that springs are allowed. Are self-closing spring hinges allowed such as http://www.mcmaster.com/#1481a12/=tvjql1?

A: Yes, self closing hinges are a legal COTS.

[Sheldon]

This year would it be legal to use non-Tetrix hubs such as this one to mount gears and sprockets to Tetrix motors?
http://www.pololu.com/product/2674 The additional set screw is attractive.

A: Yes, this is a legal COTS.

[Sheldon]

<R07> allows 3D printing of team designed parts, but can we also purchase, download and print parts for use on our robot? We live in rural Alaska and instead of paying for and waiting for shipping of the part, we would like to print it ourselves. Is this legal as long as the parts that we print are legal COTS?

A: Yes, providing the parts are legal COTS and no other rules are violated.

[Sheldon]

In Q&A answer #3, you state that fan blades and fans made out of those fan blades are legal. Along those lines, our team would like clarification on whether an entire fan, such as

http://www.robotshop.com/en/12v-16cf...lower-fan.html, or
http://www.robotshop.com/en/sfe-air-pump.html

is allowed. In particular, would such a fan violate R04c prohibiting a COTS component with more than 1 degree of freedom? Or, would it violate RG10d prohibiting pneumatic devices? If a robot were to use mechanical switches to control or redirect the air current created by a fan, would the resulting system be considered a pneumatic device?

Thanks,

FTC team 8538 (LickRobotics)

A: Complete fan assemblies violate Rules <R04c> and <R09> and are therefore not legal. Team built devices that blow air and do not result in appreciable increase in air pressure are legal providing no other rules are violated.

[Sheldon]

We were wondering if rubber caster wheel (http://www.lowes.com/ProductDisplay?...llow&cId=PDIO1) was legal. We were not sure if it would fall under wheels (legal) or COTS (illegal due to 2 DOF).

Thanks!
5950 - The Bio-Bots

A: This caster wheel is a COTS and has more than one degree of freedom. Therefore it is illegal.

[Sheldon]

Are springs allowed? In the rules it made it seem like you could: if they were not compressed at the beginning of the match. Thanks in advance!

Best regards, Jesse and the rest of team 3805

A: Springs are a legal COTS. Rule <RG10c> allows springs to be compressed (or stretched) prior to the start of a match.

[Sheldon]

Howdy,

We wanted to know if the 4 inch hi-grip wheels that were legal last year are still legal?

http://www.andymark.com/product-p/am-2256.htm

Under the description at website they say they are not legal.

Thanks!
Robo Squad 5936

A: Rule <R04d> clearly states that AM -2256 wheels are not legal.