Looking for mechanism...

[Externet]

Hi all.

Trying to find in the market a motorized mechanism that sweeps an angle of chosen magnitude; can be even a toy or toy part. There has to be something available.  Ideas please ?

Wheel W turns pushing and pulling a link L that moves forth and back a part continuosly sweeping an angle A.  + are pivots.  Varying radius R changes the angle A swept.  There may be dozens of different approaches, sketches to produce the same.

[pzkpfw]

Could you just use a servo?

If it doesn't need to be too strong, you might find a cheap Arduino kit with a servo.

Then easy to program, for how much sweep you want.

This kind of thing (skip right to near the end to see in action): 

 

[Externet]

10 hours ago, pzkpfw said:

Could you just use a servo?

Thanks.  Yes, a servo does work but strongly prefer something electronically simpler as geared motor with no circuitry as will have to work in corrosive hard-to-reach enclosure and no stepper motion but analog smooth.

[sethoflagos]

2 hours ago, Externet said:

Thanks.  Yes, a servo does work but strongly prefer something electronically simpler as geared motor with no circuitry as will have to work in corrosive hard-to-reach enclosure and no stepper motion but analog smooth.

Are you looking to operate another mechanism with it?

What's the desired amplitude, cycle period and torque?

How much space is avaiable?

Can you be more specific about 'corrosive'?

[MigL]

Sorry, but the first thing that came to  mind is an oscillating lawn sprinkler.
Powered only by water pressure, and manually selectable angle of coverage.

[Externet]

1 hour ago, sethoflagos said:

Are you looking to operate another mechanism with it?

What's the desired amplitude, cycle period and torque?

How much space is avaiable?

Can you be more specific about 'corrosive'?

Thanks. 

No, stands alone.  10 to 270 degrees;  10 degrees/second; 30 seconds, no load (no torque).   20cm x 20cm x 20cm.   No.

[sethoflagos]

 

2 hours ago, Externet said:

Thanks. 

No, stands alone.  10 to 270 degrees;  10 degrees/second; 30 seconds, no load (no torque).   20cm x 20cm x 20cm.   No.

First port of call would be a windscreen or headlight wiper mechanism from a car scrapyard. 

The cheap ones, not the ones with reversible motors.

You might get the required sweep and cycle time by tinkering with the linkage, but incorporating a reducing gear might be more productive.

[studiot]

Suggest an old fashioned mechanical metronome.

 

They can be had second hand very cheaply since electronic ones took over.

[swansont]

A stepper motor might be (part of) the solution..