How to move a robotic just arm up and down?

[deweyusa]

Hi

I'm building a "grabber" project of sorts that moves a vacuum suction cup on top of an object, then moves it to another place.

I haven't addressed how I'm going to make the general frame of this thing, or even the X-Y movement either (any hints would be appreciated). I'm starting first with trying to find a way to move the head up and down, and putting that part of the device together first.

Any idea what I could find, preferably pre-made, that would lift and lower a suction cup relatively quickly, just in the Z direction? I don't need an articulated 6-axis arm or anything fancy. I just need to move up and down. Preferably, whatever it is would be able to be relatively easily mounted in a fixture to later apply the X-Y movement.

A motor attached to a long straight piece with teeth in it for the motor to push against is about the closest my thinking has taken me, but I'm stuck there. Anyone have any ideas or sources to find parts like this?

Thanks for the help
-Dewey

 

[Sceadwian]

relatively quickly

Is not a metric anyone can design for...

My first thought is a simple worm drive.

I see this kind of post frequently on this forum. No one can suggest anything of value to you until you specifically define what the rate of movement and torque required is.\, let alone any other constraints you might be under.

 

[deweyusa]

Good call. Thanks for the point of clarification. I'd like it to be able to travel 5 inches in about a second.

I got to snooping the web, and although it'd add the complexity of an air compressor, I found pneumatic cylinders, which seem like they might be a good fit too.

 

[Sceadwian]

Then you mean up and down to absolute deadstops without positional awareness?

 

[deweyusa]

Well, I'm trying to suction-grab pieces from the top of a pile of paper with a vacuum attachment on the end of the arm, so I'm thinking I'll need to slow down when I get close to the pile of paper. Since the pile height will change as paper is picked up, I think I will require a sensor at the end of the arm to at least slow it down when it gets close, maybe in addition to a switch of some kind on an extension that rides right next to the vacuum cup to sense when the cup has touched the paper.

(Think of those videos of the US Treasury picking up sheet after sheet of $100 bills and moving them around).

 

[Sceadwian]

Think mechanically not just electrically it makes things much simpler. If you use an absolute up down to dead stops with decent force actuator which is very easy to control electrically you can adjust for the changing paper height and add a damping factor with a simple spring of the proper length and wire thickness, perhaps more than one to allow stiff absorption with a heavier spring to prevent mechanical shock from the dead stops and a finer one that would add more buffering and allow the actuator to adjust to the paper height.

I keep all the springs from things I take apart, never ever throw any out. I have everything from the most delicate springs that would deflect from the weight of a piece of paper or 10 or 50, to recoil springs from the hinges of lidded chests that keep it from slamming with dozens of pounds of force.