Hello Everyone,
I’ve been trying to research how to set up a window motor to control a leadscrew. I’m not having much luck. Is there anyone that can show me an example? OR if there is other ways to drive a leadscrew for linear motion I would be interested in seeing those examples too.
Thanks,
Tony
Don’t.
Leadscrews are most useful when a high-torque, non-backdriveable mechanism is required. Window motors are already non-backdriveable (they have an internal leadscrew), and are seriously underpowered.
I loved the window motor back in the day, but there’s really no use for it in modern FRC - especially not driving a lead screw.
If you describe your mechanism in more detail, people can probably give you sound advice on how to power it.
We do whatever it takes to avoid that kind of linear motion! because it is really hard to do effectively.
Seems we can almost always figure out a way to do it with an arm or 4 bar linkage of some type, usually actuated by a simple pneumatic cylinder.
Not knowing what you have in mind, though, it’s hard to offer more specific advice.
It’s going to be used to change the angle of a hinge mounted shooter.
Oh. We’re changing the speed of our shooter wheel to accomplish that. No hardware needed.
Do you need it to be infinitely variable? would a piston work for 2 position? or even a servo depending on the implementation might be of use
Yeah, the kids want to be able to control it’s angle from any distance. We thought about a piston, but not sure if we have the skill set to implement that at this point.
I also thought about purchasing a linear actuator. Essentially the the shooter the mechanism would need to push the shooter apparatus forward to tilt it up retract to lower.
You can adjust the speed the shoot from any distance within your range.
A piston is a lot easier to implement than a lead screw/linear actuator. Plus, you don’t have to worry about its position as much, because it’s binary. 254 did it in 2014, and 118 did it with a servo 2017.
Ok, i’ll research that a bit more. We are a very small team in rural NC. I’m one of 3 mentors at the moment, I’m the only mentor with any technical abilities, so I end up helping them with the mechanical build and programming. I don’t have a ton of experience with either, so all of this has been a challenge. I appreciate the suggestions so far!
Sounds to me like you are in a situation where you would be better off finding ways to NOT build extra mechanisms. It’s pretty late in the build season, you know.
If you’re worried about experience, I might recommend using a fixed position hood to start, and get velocity control running well on that. After you get that down, you could consider switching to a 2 (or infinite if you’re confident you can do it) position hood; that shouldn’t be a major change as long as it’s planned out in advance. With no bag you’ll have lots of time to adjust, make changes, and work on programming if you think it’s something your team could benefit from.
I’m very aware… But we are trying to get the design done… so i’ll continue to help them any way I can.
Thanks, i research that and see if it’s something we can implement over the next week!
Well, I don’t have much opinion on whether or not to use a lead screw for this mechanism; but if you want to do it, I’m pretty sure that’s exactly the application the Johnson Electric motor available this year through First Choice was designed for:
https://wpilib.screenstepslive.com/s/currentCS/m/kop/l/1164514-johnson-electric-plg-motor
I don’t have a lot of advice for how to achieve the connection to your lead screw, but perhaps someone on the forum has already done this and can chime in
I’d put a pulley or sprocket on the shooter hood and drive that with rotary motion.
What you are describing sounds a lot like a dart actuator. I have no idea when they will be available, but regardless I think this is a good example of how to drive a lead screw with a CIM motor (or neo or falcon). With a Vex pro Cimile, you could use most other motors too.
We have had luck in the past buying lead screws and nuts off of McMaster for mechanisms, and driving them with Andymark Hubs and pulleys. The new redesigned andymark hubs actually work really well in this application, because now the “Cim Hub” fits in the 42 tooth pulley. We have had success drilling a pin through the hub and the lead screw to hold the lead screw to the belt.
That said, a lead screw mechanism takes a lot of thinking, and some custom machining to get working right (at least with the design I described). It may not be practical for your application.
The dart actuator is very much what we have envisioned. Do you happen to know if it would be illegal to just purchase an aftermarket linear actuator similar to the dart actuator?
Someone please correct me if I am wrong, but I believe that you could use the mechanical components out of one (assuming it is under the $500 limit), but you cannot use the electric motor, because it is not FRC approved.
It is probably possible to adapt an FRC approved motor to the mechanical parts of a linear actuator, but that could prove to be difficult depending on your machining resources. VBX Bearing has some neat looking actuators that may be possible to adapt.
These gems exist too for low powered applications.
They could be used for moving a shooter hood depending on how you choose to do it
I can share some design ideas for implementing the Johnson Electric motor as a linear actuator but needs a bit of fabrication precision. At a sacrifice of some durability maybe a few things can be comprised. The adapter has an 8mm hole which fits many lead screws you would find on Amazon. A pin or set screw would lock the lead screw in the hex adapter.