Motor and part design for lowering / raising golf simulator screen

Hi there, I’m building an indoor golf simulator, and as part of that, I have an impact screen (think large projector screen) that I need to raise / lower. I’ve got the screen mounted on a 2" diameter mild steel tube sitting in pillow block bearings - so it rotates freely. On the end of the tube, I have a sprocket mounted (30 Tooth 08B Simplex Taper Sprocket to suit 1/2 Inch Pitch Chain)

I’ll be raising and lowering a screen made of approx 750g/m2 fabric from the pipe down 2.7m to the ground. So when fully extended, the first rotations need to lift ~6kg of weight. So 58N, if I’m thinking about it the right way. And the radius (let’s assume 3” - 1” for the pipe and then 2” more for the fabric wound around it). So 0.076M x 58N = 4.48 Nm

I’m planning to us a chain around the current sprocket and run down to a [x] tooth sprocket that I can mount to the shaft of a worm gear stepper motor with grub screws to the shaft. (am I going to have a connection issues with grub screws? do I need to key the shaft?)

I want to be able to control speed and direction and start/stop as needed. I’m happy to hold button as it goes, I don’t need it to ‘know’ when to stop/start.

I want it to hold position without requiring power (so worm gear, right?)

Thinking something like this:

  • Nema23 work gear motor - https://www.robotdigg.com/product/567
  • But I’m trying to figure out the right size / power setup
  • call it 2.5” radius on average, 15.7 inch circumference. Need to lower 2.7m of fabric (106 inches) - so 6.75 rotations if I got a matching gear for the other side of the chain. More/less if I got a different gear to attach to the motor.
  • I’d say target 30 seconds or less to raise/lower = so 3-4 RPM. Or if I go with an 8 tooth gear on the motor, I’d get 4rpm at the 30t gear with 15rpm at the motor.

Parts list, as I see it:

  • Worm gear stepper motor - I’m struggling to find a site / way to search for something with the right combination of RPMs and torque - suggestions on motors or places to look?
  • I need some sort of button/dial setup for controlling it (guessing those can be had pre-fab without having to buy the individual elements?)
  • I need some sort of controller (raspberry pi/otherwise) - I’d guess this is a common enough application that I don’t need to actually code my own setup and can buy this prefab? I’ve done DIY coding with particle photos and built my own iOS and web apps, so I can if needed, but feel like that could be avoided?
  • I need some sort of power supply that I can connect to the mains (UK) power - what do I need for this sort of setup?

Overall, I’m a pretty capable DIYer but haven’t done anything with gears and motors, so am lacking a bit of context and examples. I’ve done a fair bit of research and reading on my own, which has gotten me to this point, but could use some experienced advice. Thanks!

Any type of gear really.
What you need is the holding torque to be high enough even with the power cut off.
Permanent magnet motors will help with in this case.