We were thinking of using https://www.firgelliauto.com/products/light-duty-rod-actuator as an alternative to the DART actuators, but we weren’t sure if these would be considered legal. Anyone have insight on this?
We’ll start with “Does it meet the motor rules?” and go from there.
Is is powered by a legal motor? No. (Unless it is and they’re not saying anything.)
Can it be modified to use a legal motor? Good question. I’d say “possible” but you’d have to do your own engineering on that.
You would need to swap out the motor to an FRC-legal motor, but there’s no reason you couldn’t use the physical actuator mechanics.
These actuators also have build in end of travel switches that appear to actually carry motor current (or rather, interrupt current at the end of travel – watch the video). This would not be legal for a FIRST robot even it had a FIRST legal motor.
At least that is how I read the rules.
Dr. Joe J.
Thanks for the advice 
What rule are you referring to that would prohibit this sort of end-of-travel safety switch? I’m looking at the rules regarding motors and actuators right now and I’m not seeing anything regarding this sort of switch. Am I missing something?
Our team is hoping to buy a similar linear actuator and swap out the motor for a FRC legal one.
Thanks
It’s not a motor rule, it’s a control system rule. All motors have to be controlled by the control system, and nothing else.
I suggest you read the rules about the control system, and see if I’m right. I might not be!
but my guess is you have to re wire it so the FRC legal motor you install is connected directly to a speed controller, and the limit switches are connected to a digital input on the roboRio
CUSTOM CIRCUITS (like limit switches) can’t interrupt a power wire that feeds a motor. (R55) The switch would have to be wired into the RoboRIO or speed controller that has limit switch inputs.
R55
CUSTOM CIRCUITS shall not directly alter the power pathways between the ROBOT battery,
PDP, motor controllers, relays, motors and actuators (per R28), pneumatic solenoid valves, or
other elements of the ROBOT control system (items explicitly mentioned in
R66
).
Using a limit switch in the power path between the PDP and Motor Controller, or in between the motor controller and the motor, would be a custom circuit. Not allowed in the power path.
Limit could be wired to DIO as inputs, or to the motor controller directly as overtravel limits, and be OK.
Can you not just dissconect the Micro switches inside which are whats used to control end of stroke power shut off ?
Thanks for the info. I think I understand now.
Has anyone been able to successfully modify the firgelli actuators to be legal? We have four of them here that I’d like to use. We have darts coming tomorrow, but I’d prefer to use the firgellis because of the size. The darts seem to be considerably larger from the pictures.
Our team has successfully swapped the stock motor on this: https://www.servocity.com/html/25_lbs__thrust_linear_actuator.html#.VrEBX7IrKUk
It’s very similar to the firgelli ones by the look of it. We used a vex bag motor and it seems to have ample power. The hardest part is coupling the nylon pinion gear to the bag motor shaft, if you have a good machinist, it’s doable though. As stated above, the in-line limit switches have to either be disconnected altogether or wired up to the roborio to be legal. At this point our team has just disconnected them because they weren’t working as we had though they would.
I’ll try to get some photos of the inside of this in the next day or two.
Also, when we got the actuator working with the new motor, the in line limit switches weren’t connected (obviously) so we accidentally stripped out the nylon pinion gear, (I’m not sure what sort of pinion gear the firgelli ones use) Servo City customer support has been very helpful in ordering replacement pinion gears. Just be aware when you guys are messing with these actuators not to damage the pinion gears like we did, or anything else for that matter.
Sorry for not having more specific details or photos at the moment. I’ll try to update with more info soon.