[FTC]: Parts Question

[Monty Python]

Last weekend I saw this scissor lift at a championship. It was really impressive and could lift two crates 4.5 feet. They drove the lift with a threaded rod and a bronze thing. However, I could not find the bronze thing on the Tetrix website. Where could I get something similar to that?

[Madison]

It is an acme thread and acme nut.

I don't believe their use satisfies R5c18 and wouldn't allow them to compete, but I am not an inspector for FTC.

[Rainydaymaker]

Check out ruling #33 in the Forum. http://ftcforum.usfirst.org/showthread.php?355-The-Robot-Parts-and-Materials&p=2130&viewfull=1#post2130

[Monty Python]

That team won the championship and qualified for St. Louis using that design. What is the community norm for a situation like this?

[kz2zx]

"Any thread, any fastener".

TC0092
We are confused about the two answers that seem to be conficting. In The Robot Parts & Materials post #19 ACME threaded rod IS allowed. In The Robot Mechanical Answers post #2 a Lead Screw IS NOT allowed. We believe ACME threaded rod is a type of Lead Screw. If you go to McMaster and search for Lead Screw you get to ACME Threaded Rod.

Can you reconcile these two answers?


A: In light of the confusion and ambiguity that surrounds threaded rod vs. lead screw, the Game Design Committee has decided to allow any type of threaded rod/lead screw that conforms to the initial limitations (i.e. 3/8" diameter or smaller). This allowance also includes compatible nuts for the threaded rod/lead screw.

[Al Skierkiewicz]

The FTC forum answered that lead screws specifically are not allowed. This appears to be a lead screw from my experience. while they have won an event, I don't think it can be taken away, but inspectors at Champs may find a problem with it. If I was the team, I would think about an alternative mechanism. 3/8" threaded rod is allowed.

[Monty Python]

I found the actual post Al Skierkiewicz was mentioning. So are fasteners that are not similar to tetrix fasteners legal?

10-17-2011, 07:17 PM Originally Posted by FTC4356
We were wondering if the use of a Lead Screw with nut allowed as long as it is under the overall rod size constraint of 0.375in? Such as the lead thread that was included in the 2011 kit of parts for the FRC competition (PN: BZ8M16 x 15").
http://usfirst.org/uploadedFiles/Rob...%20Rev%20E.pdf
(bottom of pg. 13)

A: No, a lead screw is not All-thread. Nor is it a fastener.

UPDATE 10/25/11 - Lead Screws are now allowed. See Post #33 in Parts and Materials

[kz2zx]

Al, http://ftcforum.usfirst.org/showthread.php?355-The-Robot-Parts-and-Materials&p=2130&viewfull=1#post2130

Monty, any nut/fastener is allowed. Screws are limited to machine-type (not sheetmetal or wood-type, and I think self-tapping is also excluded).

Check out the entire Materials thread in the link above...

[Al Skierkiewicz]

Thank you for the update.

[normalmutant]

Oh hey that's our robot! Yes, we use 3/8" double-threaded (acme) rod. We got it from McMaster-Carr. I'm not sure what nut that is exactly, but we did have to tap it in order to attach it to our lift.