Accurate movement on high torque motor

I am trying to find a motor that, when attached to some sort of turn table (like this http://goo.gl/zAZxr), will be able to make accurate discreet movements of around 6-10 degrees when a load of around 6kg is placed on top. The plan is to keep rotating the disk until the motor has rotated 360 degrees and returned to it's original position.

I assume this will require some sort of fairly high torque stepper motor, does anyone have any suggestions as to what would be the best solution?

Many thanks,

hcaw

I've had a look around and it looks like the "Big Easy Driver" is probably my best option for running the motor as it can handle up to 2A/phase. I'd like to find out how strong the motor will need to be though - guess I'll just buy the biggest one I can find!

The quality of the bearings will be the most important factor - for a horizontal turn-table with very good bearings
very little torque is required. The effective diameter of the bearings also matters.

You also need to have enough torque to accelerate the load, but you haven't said anything about how fast
you want to move it.

You might get the accuracy you want using a large sail winch servo.

hcaw:
I am trying to find a motor that, when attached to some sort of turn table (like this http://goo.gl/zAZxr), will be able to make accurate discreet movements of around 6-10 degrees when a load of around 6kg is placed on top. The plan is to keep rotating the disk until the motor has rotated 360 degrees and returned to it's original position.

I assume this will require some sort of fairly high torque stepper motor, does anyone have any suggestions as to what would be the best solution?

Many thanks,

hcaw

As stated by others make sure you have this well balanced and good bearings on it - the weight will then be fairly easy to manage.

I have this stepper motor and the easydriver from Sparkfun that i use in a chicken coop for raising and lowering the door - the door weighs 3.5Kgs and binds a little in its tracks so i think this would easily do what you want.

You want to be careful to not rely on the bearings of the motor to support the system - rather a belt drive would be better.

and this driver board

Craig

lazy Susan platform

http://www.homedepot.com/p/Shepherd-6-in-Lazy-Susan-Turntable-9548/100180572#.Uei7QinD_iw

zoomkat:
lazy Susan platform

http://www.homedepot.com/p/Shepherd-6-in-Lazy-Susan-Turntable-9548/100180572#.Uei7QinD_iw

Love it !! Not sure of the quality of the bearings though ?

Craig

craigcurtin:

zoomkat:
lazy Susan platform

http://www.homedepot.com/p/Shepherd-6-in-Lazy-Susan-Turntable-9548/100180572#.Uei7QinD_iw

Love it !! Not sure of the quality of the bearings though ?

Craig

Man i wished i lived in America - you guys have everything available just down the road !!!

So to the OP - get one of these and make a wooden base to mount the bottom to - cut out a hole in the centre of that base for access to the motor etc

Get another sheet for the top - can be anything that is dimensionally stable perspex would be good.

Now the key part is to find the exact centre of the sheet and then to ensure that the mounting points are exactly equidistant from that

I would then get a lovejoy coupler and use that to mount the stepper motor to the turntable- but a small bolt through the turntable and tighten it in place with nuts, then but one end of the lovejoy onto it and the other end to your stepper motor.

This will then give you the height for mounting your stepper underneath and you can fashion a suitable bracket

Craig

craigcurtin:
Man i wished i lived in America - you guys have everything available just down the road !!!

If only we had a place like Shenzhen just down the road...it would be perfect.

Very smooth, high quality lazy susan bearings such as this are available and even less expensive on ebay. I have used them and they rotate very easily under a heavy load. - Scotty

A small spring-balance can be useful for rough measurements of forces and torques - measure the force needed to
turn the platform well pulling on an edge, torque = force x radius. Then double the value to give a good margin
and make that your torque specification.

Alternative is a piece of string/thread over a pulley to a weight tray...

cr0sh:

craigcurtin:
Man i wished i lived in America - you guys have everything available just down the road !!!

If only we had a place like Shenzhen just down the road...it would be perfect.

Yeah it would be Heaven then !!

Craig