solenoid
I've been looking for ideas on how to launch a ping pong ball a small distance (< 1 metre) for a game. Solenoids look like they might be useful but I'm not 100% on what force/type I need. I can mount it under a base and have the balls roll over it, with a pin pushing the ball up a ramp to it's target.
As it's only a ping pong ball, it should be light. I was considering something like this:
http://www.adafruit.com/product/412
Am I along the right lines? Or should I go back to the drawing board.
The behavior you're describing (denting stuff) is a function of pressure not force. I could dent a bowling ball with a few grams of force if it was in a small enough area.
I'm not just being pedantic, it's a key to thinking of what you want to do. 24oz of force (yes, it is at a specified current) can be increased over small distances using levers, or you can get a smaller force over a longer distance, again using a lever. Force is just part of the equation; you need to consider the Work that Force will do.
No.
Yes.
:-).
The solenoid will "insist on pulling in" as it is built.
There are solenoids which can be made to repell the armature from the core, but they need permanent(usually) magnets in the core to work.
BUT
You can get essentially the same result by adding a non ferrous* extension to the core so that when it travels inwards the extension moves outwards.
See diagrams below:
Diagrammatic -
As typically implemented:
The above images are from this page.
If the coil end at the "pushing" end is open it will be relatively easy to insert something which can b pushed. If it is closed you may or may not be able to add a hole. Be careful not to drill through coild or wiring.
Many images from Google - most will be push solendoids - each is hot linked to a webpage.
Many for sale - some of these may LOOK like genuine push type but it is almost 100% certain that they will be pull type with an extension.
Dismantled:
Best Answer
A solenoid could work. Another thing that could work is using compressed air. A ping pong ball in a tube that's slightly bigger than the ball's circumference with an electrically controlled valve could do it. You would basically want to replicate a t-shirt cannon on a small scale, and use paintball air tanks to get multiple shots before having to recharge. Changing the length of the tube would also let you have fairly good control over how far/fast the ball goes (longer tube = longer time that the force is applied to the ball and so greater acceleration). I think a solenoid would be a simpler option though. I would get some large ones and experiment with the repeatability and power needed to get the ball where you want to go.