Would the following Linear Actuator be legal for us in FIRST?
The motor that is part of the actuator is not legal. You can only use the motors listed in the rules. You could try to adapt a legal motor to it, but it’s probably not worth your time.
Agreed. Unless you can figure out the motor, and determine that it is form-factor compatible with one of the legal motors, probably way more effort than it’s worth. A few alternatives for linear motion:
- DART linear actuator
- pneumatic cylinder
- Linear Servo (from for example AndyMark or ServoCity - note the $75 limit in R34)
- A motor driving a lead screw, or even a threaded rod and nut.
- Chains or belts
Thanks for your replies. We will pursue other ideas. Looking at using pneumatics , maybe.
In 2018 we used an off the shelf linear actuator, but to make it legal all we had to do was remove the built in limit switch and replace the motor with a bag motor which wasn’t a lot of work (maybe a couple of hours preparing 6 of these things)
Do you have any pictures or more specifics to share? Thanks in advance
I’ve seen this multiple times. How it goes really depends on the actuator in question. Bag, RS550’s, and 775Pros are the most common replacement motors - it really depends on what size shaft the pinion gear requires and how much room you have for the motor. It’s definitely not something you want to have to do last minute, but can be well worth it if you plan ahead and do some investigation before it goes on the robot!
Yes, Jon actually helped us with this many years ago. Let me know if you’d like to know specifically what we did with this actuator. I wouldn’t recommend it if you have other options.
Edited to add: Okay, I don’t want to be that guy that posts a problem on the internet and replies, “Nevermind, figured it out!” without posting details, so someone comes along 8 years later with the same problem and can’t figure it out
Not pictured is the shaft that we cut off from the motor inside the linear actuator. We secured that to the second Lovejoy coupler, and used those screws you see sticking out of the actuator to mount a CIM motor. It was a freak show of a device, but it worked. There was very little clearance, so I seem to remember we had to cut the worm gear off the shaft of the linear actuator motor as close to the motor as possible to get the full length.
Now I know I’ve been doing this too long… I don’t remember that at all!
Of course you don’t remember it, because you didn’t almost have your team’s robot design invalidated a week before stop build day.
I thought we already had this discussion on Reddit?
This thread hasn’t been picked up for a year but I was wondering if anyone was watching it to answer my question. Is the linear actuator I have linked below work for the FRC 2020 season? Is it legal? Is the motor legal?
It’s halfway through build season and we had already ordered these actuators and we just learned about the legality rule which may be a problem so I’d like to get some insight. Thanks.
~ Team 2594
Unfortunately, the only legal motors in the FRC are the ones listed in the manual. You may want to see if you can either return these actuators or adapt a legal motor to fit them.
Our team encountered a similar problem in 2018 trying to modify an actuator to power our scissors lift. We used this one: https://www.progressiveautomations.com/products/heavy-duty-linear-actuator
The motor in it was basically a knock off CIM and we were able to take the thing apart and put a legal CIM motor in the actuator, although it required taking the motor apart and milling the shaft to fit. The motor on this actuator looks similar, and you might be able to swap out the motors to make it legal.