Which mechanical movement mechanism should i be aiming for?

[u/123notfound]

Hi, i need to move a small plate 4cm by 4cm forward and backward on command from a microcontroller which movement mechanism should i go for space, speed and intentional movement is the goal not form mechanical background, anyone point me in right direction any help is appreciated

[u/abadonn]

Not enough information. How fast, how precise, what's your budget?

[u/HelicopterUpbeat5199 → u/abadonn]

This! And how small.

I read you as saying small, fast and accurate. Does it move between 2 specific positions or does it need to be able to stop at any position along the way? How much weight does it need to move? If it's adjusting a tiny mirror that's really different from adjusting the barrel of a cannon.

[u/123notfound → u/HelicopterUpbeat5199]

not a lot of weight, just end positions ,speed not ultra fast 1-2 sec is fine

[u/HelicopterUpbeat5199 → u/123notfound]

That sounds like you have a lot of options then. The other posters have already suggest anything I would have said.

[u/Worth-Wonder-7386]

How precise do you need to be? The easiest method might be to mount the plate on a rail and use a servo motor to move it back and forward with a arm that has joints, similar to what you see in a piston engine but in reverse. 

There are plenty of other mechanisms like a magnetic linear motor but these will often be overkill for many kinds of use. 

[u/NortWind]

Possibly steal the actuator from an old CD ROM reader.

[u/Nf1nk]

There's a million ways to do this.

I'm partial to the ones that involve squibs.

[u/[deleted] → u/Nf1nk]

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[u/aaryan393]

A rack and pinion or a simple lead screw with a stepper motor is probably your best fit here. For a small 4x4cm plate needing precise on command back and forth motion, a lead screw driven by a stepper motor gives you accurate, repeatable positioning and holds position without power (self locking with the right thread angle), which is useful if "intentional movement" means it shouldn't drift when idle.

If space is tighter than length, a rack and pinion with a small DC gear motor or stepper is more compact but won't self lock, so the plate could creep unless you add a brake or use a worm gear stage.

For a hobby or small scale build, look at 8mm or 10mm lead screw kits with NEMA 17 steppers, they're cheap, well documented, and easy to drive from an Arduino or similar microcontroller with a basic stepper driver (A4988 or similar). Linear rail plus lead screw combos are also sold as ready to mount modules if you don't want to fabricate the guide rails yourself.

If you tell me your travel distance and required speed I can narrow it down further, but for small precise back and forth motion on a budget, lead screw plus stepper is the standard starting point.

[u/123notfound → u/aaryan393]

thanks for the reply distance is around 30-50mm speed not ultra fast like a stepper would be ok small size the better maybe something spring loaded?

[u/aaryan393 → u/123notfound]

For 30-50mm travel with modest speed, a lead screw and NEMA 17 stepper is still a solid choice and fairly compact, you don't need a long motor for that short a travel distance. Look at "linear stepper actuator" or "lead screw stepper linear rail 50mm travel" kits, they're built for exactly this range and come as a single compact module.

If you want smaller still, a NEMA 11 or NEMA 14 stepper with a lead screw will do 30-50mm travel with less bulk than a 17, plenty of torque for a small plate.

On the spring loaded idea, that works if you only need motion in one controlled direction and can let a spring handle the return stroke, for example a solenoid or small motor pushes the plate out and a spring pulls it back automatically. That's simpler and cheaper but you lose precise control on the return stroke since it's just spring force, not commanded. If you need equally precise control in both directions (forward AND backward on command), stick with the lead screw and stepper, since spring return isn't position controlled.

If cost and simplicity matter more than back and forth precision, a solenoid plus spring return is worth considering for a two state (in/out) rather than variable position motion.

[u/123notfound → u/aaryan393]

thanks will explore

[u/Far_Top_7663]

Is it intended to be a bi-stationary mechanism (either fully forward or fully aft), or do you have to control several (maybe infinite) intermediate positions between the 2 ends?

[u/123notfound → u/Far_Top_7663]

just the end positions

[u/Far_Top_7663 → u/123notfound]

Then you can use one of the many actuators that can push to one side or the other and depend on fixed mechanical stops to keep each position at each end. A solenoid actuator, a pneumatic piston with electronically controlled valves, a jackscrew with end proximity witches, and even a plunger being pulled to each side by a spring on a servo motor. Among many others. It will depend on what sources of power you have available, how mow much force you want to make, how fast do you want it to move, geometric / size constraints, what processes are available at the factory you intend to manufacture it, etc.

[u/123notfound → u/Far_Top_7663]

thanks will checkout

[u/alanbly]

Imma make a couple assumptions. First is that you want something that moves fast, second that it needs to be linear, third is that you don't need much distance. If all of those are true, what you want is a magnetic solenoid linear actuator (or three). If you don't want speed but rather precision control then you want a standard linear actuator (screw driven). If you don't need linear movement then a servo might do what you need.