The Robot - Parts and Materials

[Administrator]

Answers to questions about Parts and Materials will be found here

[Raj]

Which HiTechnic IR sensor is appropriate for finding the IR beacons? I could not find one on the parts.ftcrobots.com website, but I found a few on the legoeducation.us web site.

Any IR Sensor is allowed, however we found that the IR Seeker V2 (Lego Ed Product ID: W991379 or HiTechnic Product ID: NSK1042) is very useful with the IR beacons.

[Professor Proton]

Our team, like many, is under budget and schedule constraint. We believe we can order some parts from second-source suppliers (e.g. Amazon or McMaster) far more quickly than from Pitsco or Lego Education.

Q1: The general case: May we substitute parts in the Tetrix system with another part from another source that is in the same spirit as the Tetrix part? For example, a motor encoder that matches the performance of the Tetrix part (i.e. 2-bit quadrature 400 bpr), or a servo that is continuous-rotation or 180-degree with similar form factor, performance, and identical electrical interface? In many cases we can source parts from Craigslist or community (R/C hobbyist servos, electronics, etc.) for a lower cost.

Q2: Our team's specific question: May we substitute a machinable-bore (1/4" unfinished) #25 16, 24, or 32T sprocket? Aluminum sprockets are harder to find, and ones with custom bores harder still. May we use a pre-formed sprocket constructed of a of a more-delicate material (Nylon), or may it be of steel?

A1: No. However, teams may purchase identical (manufacturer, model, etc.) parts from any source. For example, teams may purchase the HiTEC HS-485HB servo from Pitsco, Amazon.com, hobby shop, etc.

A2: No. The game manual specifies all of the allowed parts. Parts that are not specifically allowed in the game manual are not permitted.

[Professor Proton]

My team read the rules clearly and have a question about the amount of allowable material teams can use in addition to the kit of parts. The rules state that for example teams can use aluminum square tubing not to exceed 1" x 1'"with no maximum length. Our question is that since there is no limit of tubing as long as it meets the 1" x 1" requirement. We have design plans that if this is true will use a large length of square tubing. Please verify so that I may direct the team in the correct manner and we do not waste our build time on a rule breaking design.

Thanks,
1033

There is no limit to the individual piece length or combined total length of 1" x 1" aluminum square tubing used in robot construction; provided that no other rules are violated. For example, the robot in its match starting configuration is required to fit within an 18" x 18" x 18" cube as described in rule <R4>.

[Professor Proton]

During today's team meeting, questions were raised about Section 4.2, subsection <R5> part c (page 32-33) of the FTC game manual. <R14> mentioned parts modification allowed but left out majority of the parts allowed in <R5>. Can we modifications (drill, cut, machine, etc) allowable parts in <R5> (items 6-11, 29, etc) to construct functioning parts of the robot, i.e. grabber, harvester, etc?

Yes.

The intent of rule <R14> is to restrict modification of electrical components and prohibit welding, brazing, etc.

[Wil Wheaton]

Are teams allowed to use FTC acceptable parts to create a magnet to identify magnet balls?

A: In short, yes, as long as no other rules are violated.

In particular, be sure to read and completely understand <R5>.a.4 and <R5>.d.7 with respect to
powered circuits.

[Wil Wheaton]

Rule <R5c18> allows "All mechanical fasteners (nuts, bolts, screws, etc.) of any length, any thread type, up to 0.375" (0.9525cm) diameter." This is followed by a confusing statement of intention. Are ALL nuts, bolts and screws up to 3/8" diameter allowed? Wood screws, sheet metal screws, countersunk screws, barrel nuts, plate nuts, anything threaded (up to 3/8") goes?

A: The key phrase in <R5>.c.18 is "substantially the same as TETRIX fasteners". The intention is to allow other nut/bolt/machine screw type connectors, not any type of screw. Wood and Sheet Metal screws are NOT allowed. The various types of nuts you mention would be allowed.

[Wil Wheaton]

Thank you for addressing our question regarding rule <R5c18> earlier!

Could you please further clarify this rule...

Are socket head screws, cap screws, and machine screws of any head type allowed?
Are countersunk head screws allowed?
Does any thread type mean "any" thread type? Coarse, fine, SAE, metric?
Must all mechanical fasteners be steel or are other materials allowable?
Are any compatible nuts allowed? Acorn nuts, wing nuts, self-locking nuts, castellated nuts?
Can the wire rope of rule <R5c15> be used as safety wire?

Thanks so much!

A1: yes
A2: yes (really the same question as #1 )
A3: yes
A4: there is no rule that implies any particular material to screws/nuts/bolts
A5: yes, yes
A6: yes, <R5>.c.15 does not imply how wire rope is used. Just be sure not to
violate any other rules.

[Raj]

Under Material constraints it says: " 24” (60.96cm) maximum dimension on any one side" How would this be measured in the instance of a circle or L-shape?

A: For the circle, measure the diameter. For the L-shape, measure the side of the longest length (in typography terms: either the stem or the stroke)

[Wil Wheaton]

Rule <5>.c.17 states:
17. Unlimited length Threaded Rod (also known as All Thread) not to exceed 0.375” (0.9525cm)
diameter (e.g. McMaster Carr Part #94435A317).
Numbers 7-11 specifically state "aluminum", 17 does not. Does this mean we can use another metal all thread, as long as it is the same size?
Thanks.

A: Yes, as long as no other rules are violated.