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Mechanics and Construction => Mechanics and Construction => Topic started by: PhatNinja on April 11, 2012, 12:43:19 PM

Title: Best 5lb-ft (or 30 N-m) linear actuator for paintball?
Post by: PhatNinja on April 11, 2012, 12:43:19 PM

Hey all,

GOBLIN manufactures a single shot paintball marker (http://www.goblinpaintball.com/product-description (http://www.goblinpaintball.com/product-description)). If you look on the right hand side of the page, third image down, there is a picture that shows kinda how this works. Basically the silver "round" is the CO2 storage tank AND the valve to release it. A person fills up the silver round with CO2 prior to using the marker or gun, pulls the trigger and releases enough CO2 for a single shot.

I want to use silver round idea in an R/C tank. I didn't want the big marker and CO2 tank, since it wouldn't look right and I didn't want to shot a whole lot of paintballs, just one or two.

My problem is figuring out the best way to push the valve open in a small space without having to put a big battery on it.
I like the linear actuators, but their cost can be a bit high. I saw another post on this forum for making a linear actuator out of a servo, but the servos don't seem to get enough torque without approaching a linear actuators costs.

Is there a way I'm not thinking of? 

Specs on the problem -
Force to open valve : 5-8 lb/foot or 30-40 N-M
Space : 1.5" W x 1.5" H x 10"L

Thanks in advance!

Title: Re: Best 5lb-ft (or 30 N-m) linear actuator for paintball?
Post by: Robot Attack on April 26, 2012, 02:07:52 PM

I am assuming you have to push on the canister with a pin or something in order to trigger the valve. If that is the case, what is the force required to open the valve? The values you have listed are torques.

Remember that you can always trade speed for torque by using reductions (gears are a primary example of this). In your case perhaps a simple solution would be to have a linkage where the motor pulls on the long arm and a pin is held in the short arm (This is what a trigger essentially does - using a long stroke at a low load to compress a stiff spring a short distance until the firing pin is released).

Once you determine the linear force you require, you can design your linkage around the largest motor you are willing to accommodate.

On the other hand, for this application what you might not want to use a motor at all, but a solenoid instead. Solenoids are electromagnetic linear actuators.

See: http://www.societyofrobots.com/actuators_solenoids.shtml (http://www.societyofrobots.com/actuators_solenoids.shtml)