Compiling Outdated FTC Information On ChiefDelphi

[guineawheek]

From about 2013-2015, FTC gradually loosened its parts rules from one where you had to buy Tetrix kits and had limited quantities of outside parts to one where nearly anything goes provided it is sold with “one degree of freedom”

However, there’s a lot of threads here that predate the Open COTS era that still appear in things like Google results, confusing people with outdated information.

The idea of this thread is to mention these outdated posts here so a little note will appear linking back with more up-to-date information.

That said, you should double check with the current game’s Game Manual 1 and 2 as well as the Q&A before taking anything posted here as gospel, as this thread will eventually age as well.

As such, in no particular order:

Pre-drilled C-Channel and Raw Materials

Is this channel legal for FTC?

Nope. I’m not going to the rulebook to find the rule and quote it, but you’re only allowed to use aluminum parts other than Tetrix, Matrix, or Lego if they’re in raw form. The C-Channel from AndyMark has had holes pre-cut, and would not be considered raw, and thus illegal.

Pre-drilled (processed) metal parts such as C-channel are generally legal nowadays. This is what lets goBilda (for example) be legal in FTC.
Other solid materials are generally also legal if they are not hazardous.

The exact verbiage from the CENTERSTAGE game manual is:

Teams may use raw and post-processed materials to build their Robots,
provided these materials are readily available to all Teams (for example, McMaster-Carr, Home Depot,
Grainger, AndyMark, TETRIX/PITSCO, MATRIX/Modern Robotics, REV Robotics, etc.).

For more information, see the Robot Mechanical Parts and Materials Rules section of Game Manual 1.

Custom Axles (aka: What’s Better than Tetrix D-Shaft?)

[FTC]: Alternative to axles? Does hardening work?

Purchasing D-shaft is not legal, since the flat makes it a custom machined profile, and only round, square and rectangular profile metal bar material is legal. You have to buy hardened round shaft and grind (Dremel) the needed flats, for at least the lengths where the screws grip, if not the full length. We design to avoid, as much as possible, applying any torque through the TETRIX shafts, and to always have both ends of shafts supported when bending forces are present. Bolt the gears toget…

[FTC]: Custom Axles

Unless you are giving them away, I do not think it is legal for teams to do group orders for custom made parts. Also, I advise keeping the axle OD matching the bronze flanged sleeve bearings of the Tetrix parts line, since these sleeve bearings are usually what is supporting shafts and axles, and what fits with the Tetrix channel. For long shaft needs, you can get hardened shaft in .1875" and make that work by grinding flats where needed. For shorter needs you can also get extra long 10-32 ha…

Making your own axles or even doing group orders for custom made parts is legal. (Use FTC11468 for 5% off your next Fabworks order!)

Third-party D-shaft has also been legal for some time, and in general pre-machined parts are legal provided they are sold with one degree of freedom.

If you’re worried about shaft strength (a fair concern for Tetrix D-shafts), 12mm hex goBilda REX shafts have been available for some time. These shafts additionally don’t need set screws as hubs and spacers instead clamp to the shaft and are considered far more reliable.

Vex Parts

[FTC]: FTC vexmetal

See in the rules about vex motors. Double checking can we use the metal and wheels from the old vex kits also this year. Especially since they said something about predrilled metal

[FTC]: Motor encoders Love'em? or leave'em?

DavisDad, regarding the VEX mechanum wheels, I am not sure if their square axle material is considered legal for FTC. We also used these wheels this year and made 1st seed in our 1st regional, captaining the winning alliance. We also received a Rockwell Design Innovation Award (primarily for the drive system) at our second regional. Our robot was very consistently best positioned for flag winding and still able to get back on the bridge in correct location for executing a potential double hang…

Once again, pre-drilled metal is legal now, as are other build systems. The Vex mecanum wheels, square axles, and even 393 motors are legal.

However, goBilda, REV, and AndyMark all sell better mecanums, better axles, and better servos that don’t have a million degrees of backlash unlike the 393.

And perhaps most importantly, they’re also not Vex.

Wheels larger than 4" and Hi-Grip Tread

[FTC]: Can I add non-slip material to 4" Tetrix Wheels?

R5 o. Wheels of any type up to 4” diameter. Wheels that have exposed features likely to cause damage to field and/or game elements are not allowed. Emphasis mine. My opinion, in addition, is the non-slip makes the wheel larger than 4".

Wheels larger than 4" are legal now but hi-grip tread isn’t. Be aware that high traction wheels are subject to the field damage test.

Ball bearings

[FTC]: FTC Ball Bearings

Are we allowed to use ball bearings in FTC? Thanks!

COTS Ball bearings are very much legal nowadays. Please use them instead of bushings.

Partial vacuums

[FTC]: Using Vacuum instead of Pneumatics?

I just viewed a ‘How it’s Made’ about using a 12v vacuum pump, a latex balloon, some coffee grounds, and a showerhead to make a vacuum based gripper. I read in the rules that pneumatics were not allowed for FTC but nothing about vacuum operated systems to pick up the vortex ball. We are kicking around the idea of building a scissors styled extender with a vacuum system built in to hold the ball as it is extended. I like to keep things simple and robust and am thinking this is about as simple …

Partial vacuums were made illegal in the evergreen rules some time around 2020 for better or worse. Coffee grounds are not legal as they pose a delay-of-game risk. Vacuums did make some interesting designs when they were around though – for example, here’s a team that season who managed to cap the vortex ball mentioned in that post with a suction-based mechanism.

Casters, omniwheels

[FTC]: Caster?

I’m just a teacher, not an engineer and wanted to see if we could use a caster (360 degree mounting). Some of my sophomores had an aha moment and wanted to build a triangular shaped robot with a caster in the back to facilitate turning. I won’t crap in any student’s hat when they bring an idea to the table. Just wanted to know if this caster assembly would violate COTS rules of one degree of freedom. I’m thinking probably because it can rotate 360 degrees. If so, it should pass because it only…

COTS casters are still illegal but frankly you should be using omni wheels (explicitly legal) for this instead. Or you could print? your own casters.

Protecting Tetrix Motors

[FTC]: Max amps for DC motor fuse

We, like a lot of team I assume, have had a big problem toasting motors. A power distribution panel was recommended so we ordered and installed a RigRunner 4005. Know we are trying to find the optimal fuse size for our DC motor controllers. Each of thr 4 on the robot are I individually supplied by the RigRunner and 3 of the 4 power 2 v2 motors. I can find that the max stall amps for these is 4.55 amps. What I can’t seem to figure out is what size fuse I should use when current is going to 2 …

Won’t comment on legality but you shouldn’t need fuses between the motor and the controller nowadays. The battery fuse will trip if you are overdrawing current (this is a concern with 6 motor drive designs).

This posts exists as before the Neverest was released in 2014, FTC teams were stuck with motors made by Pitsco that lasted a grand total of 7 seconds under stall before breaking and such teams wanted to find ways to protect their motors.

Given you can’t even buy those motors anymore, breaking motors on stall should not be a concern for the vast majority of teams. However, the current REV control system has current sensing on the motor ports which can help avoid blowing fuses or be used for intake detection.

Servo Legality

FTC has looser rules on servos than FRC does as it lacks the $75 price cap. And in general, as long as the motor operates between 5-6v and is solely powered and controlled off of 3-wire PWM, it’s legal.

[FTC]: FTC Servo Stall ratings

Are there any other legal continuous rotation servo options? (besides the 1425CR) If we move away from hitech, that also means the spline count is likely to be different, or are there better ways to interface with Tetrix than the hitec servo horn?

It used to be a more common practice to remove the end-stops of servos to create continuous rotation servos but it’s been ruled illegal in more recent seasons.

Modern vendors (goBilda, REV, AndyMark) now sell dual-mode servos that can be switched between continuous rotation or absolute position.

LED Controller Liberalization

[FTC]: Functioning LEDs?

Now I know in FRC its becoming somewhat common to have leds that serve a function but in FTC what would you do with LEDs that served a side function besides looking good and how would go about it?

Functional leds are legal nowadays and led controllers (5v/12v) that can be commanded off pwm/i2c/dio are legal, provided you don’t replace the COTS firmware. The REV Blinken is a common example. That said, the HiTechnic Protoboard isn’t legal anymore

See Game Manual 1 for more info.

Discontinuation of Actobotics

Sparkfun Actobotics==> FTC like stuff?

I looked at it and at the Tetrix line, but it looks like they have incompatible hole spacing. So rather than getting a parts boost, it’s just another jumble of possible part selections.

Actobotics would go on to dominate a generation of competitive FTC from Res-Q (2015-2016) through Rover Ruckus (2018-2019). However, it’s been recently discontinued (succeeded by goBilda).

The End of Phones

[FTC]: phones for FTC

Is there any way of learning which phones/devices will be allowed for future FTC matches ahead of time? Our team is considering buying new phones for our robot controller and driver stations, but don’t want to spend a fortune if a new one will be allowed soon.

The REV Driver Hub is now legal. It’s also likely that phones for the control system will be made illegal in the future. Generally these announcements are made in mid-July with the release of Game Manual 1.

Motor Gearboxes

[FTC]: Legal Gearboxes for FTC?

RM02, the orange box specifically. As to VersaPlanetary gearboxes, I’ve seen them used but you’d want to consult their documentation.

When the thread was posted replacing gearboxes on FTC-legal motors was legal, but seasons prior had not let it be legal.

For a brief window between 2016-mid 2017, VPs were an attractive option as NeveRests only really had the 40:1 and 60:1 spur gearboxes (the 20:1s were super fragile and the only available planetary Orbital at the time was 3.7:1).

Nowadays, VersaPlanetaries have fallen a bit out of favor for the application as there are just better and easier to use alternatives these days. goBilda now sells a wide variety of Yellow Jacket motors with varying fixed planetary sizes, while REV sells UltraPlanetaries with HD Hex — equally configurable while not needing to replace motor pinions.

If you’re really desperate though, here’s a video tutorial on how to install a VP to a NeveRest.

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Feel free to link to more topics that could use a footnote here.

[Christopher149]

Not really CD, but the Legal and Illegal Parts List feels like a hold over from the TETRIX-only days and transition out, and even still explicitly lists a bunch of TETRIX parts. Its existence seem to prompt at least Q&A every year (including one this year asking if “V-Slot aluminum legal to use?”). Its lead paragraph may say “This document is to serve as a guide; however, it is NOT an all-inclusive list.”, but there’s always a few people who seem to want to treat is as all-inclusive.

[guineawheek]

Well, for starters i would replace the Tetrix unobtanium motor here with a Torquenado and the Modern Robotics/Matrix unobtanium motor with a more common goBilda example

[Zatack7]

We’ve got a bunch of these floating around our shop from back when we were an FTC team (Bowled Over! & Ring it Up!).
Also, cool thread.