Quote:
Originally Posted by thesuperfez
We are looking to build a very similar mechanism to the arm used in the JVN bot, and dont really know too much about pneumatics. Could you tell us what the optimal bore and stroke length would be? or if anyone could explain what these things do and what they affect so that we can figure it out on our own.
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Without knowing your arm's geometry or weight it is difficult to recommend a optimal bore or stroke length.
The first thing to think about is levers. If you look at the JVN intake from the side it is basically a stick on a pivot-- a lever. A door is also a lever. If you push on the door close to the pivot point it requires much more force than if you push close to the doorknob. The same goes for the intake - the further out from the pivot you attach the pneumatic cylinder the less force you will need to move the arm.
The other factor is the angle that you push at. When you push on a door you are pushing roughly perpendicular to the surface of it. The closer you get to pushing perpendicularly to the lever the less force it will take. Think of the JVN intake in a side view again. Draw a stick version of it on paper if that helps. Draw a dot where the intake pivots, where the pneumatic cylinder attaches to the intake, and where the pneumatic cylinder connects to the chassis. You should form an angle. The closer that angle is to 90deg the less force it requires to move the arm.
That should give you a baseline to create your own setup. The JVN robot used 7/8" bore cylinders which were overkill. If you stick with that bore and keep the above two paragraphs in mind your final design should definitely have enough force to go up and down with some gusto.
Cheers, Bryan