Spin machine

[Ian PParticipant @ianp]

Denise

All those motors are OK but…

The thing you are building will change and develop as you proceed, if you have a largish revolving disk of some sort then whatever else it needs it must almost certainly have some means of accellerating from a standing start. The motors in your links are all single phase and get up to running speed VERY quickly.

My suggestion would be to definately use some sort of speed controlled motor, probably a 3 phase motor with a VFD (Variable Frequency Drive). With a lightly loaded motor it will probably run slower than 100RPM (just a guess) but more importantly you can set parameters to limit the accelleration, so for example you can set it to take say, 30 seconds to get up to speed from switch on. Stopping time too is controllable.

If you have a variable speed motor then it might give you some artistic scope to get different effects, for example on one canvas you could apply paint (and whatever else!) at both high and low speed. If the unit you build is structurally robust then you might see some useful effect from applying paint whilst actually accellerating or braking.

Ian P

[WolfieParticipant @wolfie]

Interesting discussion. Reading through, I don't think the disc has to be 5 foot, merely enough to attach a canvas to which may or may not be 5 foot in diameter.

Looking at the link Denise posted, that one runs on a simple electric drill, so to scale up is it really necessary to get really technical. Whats wrong with bolting a decent sized motor on to some kind of frame and putting a similar disc and plank on to it and then start with a small canvas and then add bigger ones and see what it can handle.

Is there a local Model Engineering Club in your neighbourhood Denise?

[Les Jones 1Participant @lesjones1]

An old washing machine machine may be suitable as a basis for one of these spin machines. The drum bearings are quite substantial. A new speed controller would be required for the motor. This could be built using a TDA1085C chip. The applications notes on this chip would be a good starting point. There is also his ready made controller that may be suitable

http://www.calenterprises.co.uk/speed.html

This would allow the disk to be brought up to speed slowly.

Les.

[Denise ConnieParticipant @deniseconnie57857]

@wolfie thats right, the disc does not have to be 5ft but then a 5ft canvas seems dreams away now, I never even thought of finding a group nearby!

[WolfieParticipant @wolfie]

Actually one other thing to note. You may notice that some of those motors are called 'single phase' and some are called '3 phase' Note that a 3 phase motor will not run off a standard household supply without extra electronics.

[Denise ConnieParticipant @deniseconnie57857]

@Wolfie, can I get a variable speed motor to run off household electric?

@ Les thank you but that looks too technical for me.

@Ian P, you have read my mind as regards to the art effect i'm after!

[Ian PParticipant @ianp]

Posted by Denise Connie on 26/02/2012 20:05:42:

@Wolfie, can I get a variable speed motor to run off household electric?

@ Les thank you but that looks too technical for me.

@Ian P, you have read my mind as regards to the art effect i'm after!

Denise

The three phase motor and VFD might be your best bet. If you know anyone good with electrics wiring one up is straightforward. You can buy ready built packages of motors and drive but they tend to be expensive compared with rolling your own.

What about buying a motor and drive that you can sell after you have finished with it? People here are always looking for variable speed motor setups to put on lathes and mills so even if the initial cost was higher than you originally hoped for the end cost might not be too bad.

To get an idea of what power motor is required you need to have a clear idea of speed range, canvas size (corner to corner) and the weight of canvas and table/rotating parts.

Ian P

[Denise ConnieParticipant @deniseconnie57857]

Hi Ian, I've been offered a mechanical variator with a speed from 200-1000 for £200+vat, which I cannot afford, so buying a motor and drive seperate would be the only possible answer for me. I can get measurement and weights of the canvases but the rotating parts would have to be a guess until I have them.

[Billy MillsParticipant @billymills]

Why not use a scrapyard car starter motor and car battery? You can vary the speed by connecting and disconnecting the battery using a starter solenoid ( relay) from some way away for safety when testing the thing out. A rigid support may not be needed, when you spin the cloth from it's centre it will tend to go flat.

Harmonographs are easy with a digital camera pointing upwards at the bottom of a stairwell. Suspend a torch minus the reflector ( or just a led) from a cord above the camera, swing the torch and open the shutter. More interesting patterns if you attatch a small weight to the cord between the hanging point and the torch to make a compound pendulum. You can increase the pattern range by putting the camera on another pendulum.

Billy.

[Martin KyteParticipant @martinkyte99762]

Conceptual leap sideways. How about a free spinning disk spun up with an airline running on the periphery (or even the outside ;0) )

Martin

Edited By David Clark 1 on 28/02/2012 09:18:42

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