Mechanism to Rotate and Hold a Plastic Strip in Place

I would think stepper motor for this, in lieu of various mechanical schemes. (But I wouldn't rule out some mechanical ideas such as solenoid-driven stop pins with a friction drive for rotating the workpieces.)

There is also a device called a "Geneva Mechanism" that might do what you want.

Let me clarify the drawing.

The positions and color of the plastic rectangle was just to show the movement.

It is the same piece rotating over the bottom circle. I checked your 'geneva mechanism' ... does not fit the movement of what I want.

I will check out the 'solenoid-driven-stop-pins with a friction drive'

thanks

I am updating/clarifying my request:

I am looking for a mechanism that will permit me to rotate a thin piece of firm plastic over the x-axis.

I need to move the plastic up-and-down and make it stop wherever.

When I stop, it should not fall down. It should stay where it was stopped.

Thanks

I like the stepper motor option mentioned earlier. Do you see a reason to NOT use it? Steppers with 200 steps per revolution are common, and higher resolution is available, if not by half-stepping, then by gearing or spending money on a larger diameter/lower step-angle motor.

... could also use a 1.8°/step (200 step) motor with a microstepping drive. 4000 steps/rev is easy enough to get (though the angular accuracy of the microsteps wouldn't be quite as good as a precision gearbox (very expensive!)). I agree that a stepper is the obvious solution for this app.

coolxtrader: What are your specifications? (speed, accuracy, resolution etc)?

Hi Everybody

Sorry for the late reply... Kids graduating

I apologize if I am misleading you on this request. The suggestions so far are out of scope for me.

I am looking for Non-electrical; simple mechanical solution -

* like spring assembly OR some combination of gears that will keep the 4"x10" plastic in place as I move it up and down over the x-axis

I have very limited space to put this contraption. It should fit in a space of 3/4" dia and 3/4 to 1" long.

Thanks

Local hardware store, 1/4-20 bolt, nut, 2 metal washers, and 2 friction washers.

Thanks mjb... will get to the store tomorrow and give it a try. Will update you all.

Thanks

Magnets? What else from here, Ky.

I like magnets and their uses... can you expand on your suggestion.

I tried permanent magnets... the pull force is great to hold the plastic; BUT

when the magnets are held vertical; the plastic rotates without any control. I cannot stop it where I want.... very disappointing

can you expand on your suggestion.

I could, but not in the environment of a thread and with not knowing what the end result has to look like and what it does when, where, how fast, operated by whom, how often. It would be a different matter if we were standing at a workbench, preferably my workshop with a couple of beers and a few magnets and the missus not in sight.

I could elaborate till the cows come home but in the end it is you who is doing this for a reason or two. You have to supply more details about what you are going to be using it for. A piece of string is 43,58mm long and the color can not be shown because it is inside a dark box (your use, application). Hope I haven't over looked this somewhere.

Be congratulated to your tenacity and friendly demeanor. It does seem important to you but only curiosity is in it for me. Grab me a beer Mate, lets have a look at this.

Good luck, Ky.

Springboarding off mjb's answer, how about a #10x1" pan-head screw with an O-ring under the head for compressibility, then a nylon washer for friction contact with the plastic rectangle?

Thanks Tornado... will get the supply tomorrow and try you suggestion.

Thanks

After 9 replies, you still have not provided enough information.

How fast does the strip need to move? How quickly does it need to stop? How often does it need to move? How long does it need to last? Are you moving it manually, or does some device move it? Does it need to stop in exactly the same position(s) every time? Does it move back and forth between two set positions, multiple set positions, or continuously variable positions? Is the 60° shown the limiting rotation? Any other limitations ...

How fast does the strip need to move? Slow (up or down )

How quickly does it need to stop? The moment the user stops the move (up or down)

How often does it need to move? Anytime the user wants to

How long does it need to last? Not move up-or-down, until moved again

Are you moving it manually, or does some device move it? Manually

Does it need to stop in exactly the same position(s) every time? Nope, Anywhere the user wants to(within the 60 degree limit)

Does it move back and forth between two set positions, multiple set positions, or continuously variable positions? Continous variable positions (within the 60 degree range)

Is the 60° shown the limiting rotation? Yes

Any other limitations ... You have covered it all

Thanks for your questions, I hope that expalins my situation.

Ah! I now understand your problem! I like some of the simpler suggestions, such as the 1/4" - 20 bolt and washers. However, I'd use a spring for tension and fiber washers for friction.

Thanks Bill

I will give these options a try today and update.

Will you rotate the plastic part by rotating the pivot pin or will you grab the end of the plastic to rotate it? Is the grade of plastic used prone to stress cracking?

I will be rotating the part by "grabbing the end of the plastic"

Is the grade of plastic used prone to stress cracking? Yes

In addition to the bolts and nuts suggested, you could add a piece of PVC tubing as a collar, cut with a notch to act as a stop to the ends of the 60 degree rotation.

Thanks usbport... will keep that in mind... yes, that will limit the rotation to what i need.

Thanks to Everyone who has tried to give me an idea.

I was out of town and could not work on it. I am back now and will update you all soon when I try out some of the ideas.

Thanks again.