hi,
I’m in need of 2 powerful Servos. will be moving a device that weighs about 40 lbs, rotating left and right, tilting up and down. anybody know how to make one or where to source for a good value? I have a handful of small ones (plastic gears) that maybe can be used somehow. thanks
np
Best bet for cheap might be stepper motors at that size. Hobby servos generally won’t let you adjust accelerations in the servo so moving heavy objects tends to be jerky and they bounce around the target a bit. Steppers would be cheap-ish, and you can find cheap drivers and run it from an arduino to tune it in. From the stepper you could use timing belts to get up to gears (cut on the multicam maybe) and finally use a curved rack/pinion arrangement to do the movement.
An option for the tilt might be a linear actuator, depending on the range of motion you want.
If you do want servos, these are some of the most powerful hobby ones I know of: https://www.servocity.com/tm-805bb-180-servo-gearbox
I need servos 
@michaelb Do you have any experience with something like this?
It looks like I could make a servo using a larger motor and a potentiometer but IDK
TLDR: Use stepper motors or get ready for big project
What do you mean when you say “servo”
Do you mean a motor with closed loop encoder control?
Do you mean a motor with an integrated gearbox?
Do you mean a motor with a built in motor controller?
Do you just need accurate positional control?
also 40lb is not enough info to help:
How big is the lever arm?
How much movement (degrees) is required of the lever arm?
How quickly does the arm need to move?
All that to say you are unlikely to find a one size fits all solution.
Depending on the performance requirements I would strongly consider stepper motors as @michaelb pointed out. They are cheap and easy to drive with COTS stepper drivers.
If you need closed loop control I would consider using an Odrive motor controller with a custom gearbox.
http://www.banebots.com/category/GEARBOXES.html
https://www.vexrobotics.com/versaplanetary.html
So it sounds like you ‘need a servo’ because you want to be able to control the position with an RC remote?
You’re right that the system will be a servo, but what you don’t want here is a standard hobby servo like something from ServoCity, HiTech, etc, that’s what I assumed you were asking for.
IMHO steppers are the easiest electrically because they won’t require any position measurement (like a potentiometer), but a wiper motor is likely the cheaper choice.
Since James presumably has all the code published, it shouldn’t be too difficult, the harder part is probably coming up with the mechanics to rotate the device, you won’t ever really find a motor you can straight up attach to an axle and spin the thing around on. It will probably require some sort of pulleys, gears, etc.
Edit: I’m pretty sure I know where this is going and I can’t wait to see it.
I’m using a microchip that has specific connections for servo motors. The software that works with the board is programmed for servo motors.
Is there a way to use stepper motors and have the chip control it still?
They guys store is shutdown but the design is open source, so you could make your own.
What about something like this?
Yeah if it’s hobby servo outputs then it’ll act the same as an RC controller. There would have to be an arduino in between, with the steppers or with the DC motors, but it’ll work either way.
I can’t watch the video now, but I think it’s working the same as the first video you linked? There’s not a problem with it just a bit more work to get the position feedback (potentiometer or encoder) integrated. I don’t mind helping out either way, if you need.