Spin Table for a big acrylic sculpture...?

Hey guys, sorry for the somehow noob question but after hours searching the web, only added more confusion to my already confused mind!

So basically me and my girl are doing a project together, she's an artist that creates acrylic sculptures, that are quite "spiky" if you can say so... And even though the project will have some other stuff (ultrasonic sensors, ableton live, choreographers...) i'm stuck in the most basic part of the project, how do i create a speed/direction controllable spin table?!

From what i've read, i should use a Stepper Motor, and a Big Easy Driver or a Stepper Motor Driver Shield, but the sculpture will be around 5 - 7kg and something like 50x50cm large and 1m tall (2/3 of an average person's height) i think, so i have no idea how can i ensure that the motor has enough torque to spin it and how to ensure it's stability, as i never used one before nor built something like this!
And besides that, any advice on how to built it? i'd love to use acrylic as well, to keep the theme...

Any help you guys can provide i will be forever thankful! :slight_smile:

first, how fast do you want it to spin ? the slower the better.

although I am a huge fan of steppers, they are not always the best choice. great for slow speeds, loose power as speed increases.

second, balance. if you can spin it easily with one finger, you can power it easily with a stepper.

alas, power is needed for larger loads.

I have not used the Big Easy, but that has more power. if you have a 2 amp, 24 to 30V power supply you have a good start.

a NEMA23 is a good sized motor, you can deliver 2A per phase into it. and this size motor is used on machine tools by the CNC crowd.

you did not say how you plan to spin the unit. if you have a main support shaft on thrust bearings that would handle the weight. the stepper could be belt driven, means you would need to buy pulleys and a belt. lots of places sell these bits.

the XL size belts work well with a NEMA 23 stepper. the MXL are very small in comparison.

if you are driving really slow, glaciallly slow, you could use a worm gear if you can cut the threads.
Steve Bedair's 9x20 Lathe Site you can make these HUGE you have have time. they take a LONG time to make.

I am assuming you want continuous 360 rotation. if you never go around fully, there are much simpler ways.

make a stand, hide the motor under it and it will look great.

Maybe just mount something like this at the edge of the platter to spin it around, vs a having the motor as the central shaft.
http://www.mpja.com/12VDC-22RPM-Gearhead-Motor-Recycled/productinfo/19378%20MD/

First find your bearing. This is the absolutely critical part. A bicycle wheel comes to mind.

You probably want a stand which conceals the mechanism, having a platform with a "skirt" around. If you can find something already made with precision - such as a wheel - you can "rim drive" it with a small rubber wheel inside that rim. This is how most basic record players were made. You use an arm holding the motor with a spring which presses it against the rim. Since you do not desire accuracy, driving against the platform disc itself, as long as it is mounted quite flat, would also work.

If, as I suspect, you want a slow rotation - once or twice a minute - then with a good bearing, a small stepper would work just fine.