What I mean by this is a motor with a large hole in the middle, instead of a shaft.
Some motors I found allow to easily remove the shaft, but the bore/shaft diameter I need (at least 4 cm) and RPM (700-900) are not even close.
Where can I find such a motor?

(the motor has to be small. Why it is needed: http://i.imgur.com/eoL79BU.jpg )

 

Google Hollow Shaft Motors, many leads pop up?
What technology does the motor have to be?
Max.

 

I did google "hollow shaft motor" first.
Just end up with ordinary DC, stepper or servo motors with the tiny shafts missing. I need a larger aperture (4cm +). The motor also has to not be very tall, otherwise the wide angle video beam will not pass through the bore even if the diameter is 4cm+.

The motor has to be DC and the RPM controllable in some way.

 

The link appears to show a shaft of some kind?
A traditional DC brushed motor has to have an armature of some kind albeit hollow, the closest I can think of is Aerotech frame-less motors.
http://www.aerotech.com/product-catalog/motors/rotary-motors/s-series.aspx?p=/product-catalog/motors.aspx
But even these require something in the bore.
You may be able to use a hollow core shaft.
Max.

 

Try searching for "center bore rotary stage" or "center bore rotary table". The motorized rotary stages can get mighty expensive; thousands of dollars.

If you're trying to do this "on the cheap", you might just use a commonly available bearing, like the inner front wheel bearing from a rear-wheel drive automobile, and then use a small DC motor to rotate the bearing using a rubber band around the motor shaft and the outside of the bearing. Glue the bearing between a couple of flat pieces of wood product (like 1/4" pressboard/Masonite/MDF, even plywood)

 

Hm, there seems to be something else similar I just found, "hollow rotary actuator": https://www.google.com/search?q=hol...ved=0CAYQ_AUoAWoVChMIwdC_vb6ZxwIVxRUsCh2RlQJt

Anyone heard of these?

I'm beginning to wonder whether a belt setup instead of gears would work. Gears will make a lot of noise at those speeds I'm guessing. And don't know how long they will last for a project like this where it needs to rotate the whole time the device is on.

PS. Can I change topic title? I just need something which will allow me to rotate a disc shaped object around its center while having a large hole in the center. It doesn't have to be a 'hollow shaft' motor only. The search results for these have been extremely confusing so far.

 

I suggest you first find a bearing suitable to hold that disc. Something like a thin sleeve that fits inside the bearing, with the disc somehow mounted inside that sleeve. As it seems you want this to be an optical device of some kind, so you will probably need a way to center the disk accurately and tilt it so the axis of the disk is parallel with the bearing axis with some arrangement of adjustment screws.

After you have that then you can use a belt or direct friction drive or a gears or magnetic propulsion or ... to drive that assembly.

 

How small do you want it?
http://www.researchgate.net/publica...lectrostatic_planetary-armature_microactuator
http://www.researchgate.net/publica...lectrostatic_planetary-armature_microactuator