Is it possible to make a pneumatic chain bar? and has anyone made a really compact regular chain bar using 2 motors for the mobile goal? my team is having difficulties creating a chain bar using pneumatics because we wanted to use pneumatics on our other mechanisms we have on our robot. Any help is appreciated.
Yes, it’s possible. I prototyped one but I never actually built it.
I think it really depends on how much rotation you want to get out of it. If you want around 90 degrees it shouldn’t be an issue but 180 will be a bit more tricky.
Hi there! Making a pneumatic chain bar is possible, but it’s quite difficult. You need to remember that the piston stroke is just 2," so making a chain bar rotate 180 degrees or greater requires rubber banding that makes the chain bar almost weightless at all points and rack and pinion gearing. The way I’ve seen it done is with a rack gear mounted to the end of the piston, and a pinion gear driving the chain bar.
To rubber band the chain bar, you need do something unconventional such that it is nearly weightless at all points. Aeden from 6007 and I had 2 different ways to do so in this thread , Aeden’s being the more linear of the 2. You will probably want to use his method if you construct this.
Finally, you need to take air consumption into account. According to robot mesh, you get 45 piston actuation from 100 to 25 PSI. This means that if you have a pneumatic intake and a pneumatic chain bar, assuming the chain bar using a double acting piston, you can only process 15 cones before going down to 25 PSI. Thus, you will either need pressure regulators or a limited piston stroke to save air, both of which restrict the amount of torque your chain bar receives.
Given all of these factors, I’d say to slap 2 motors on the chain bar rather than relying on a piston, but if you think you can make it work, go ahead. Alternatively, you could try a horizontal “swing arm” like 185A in skyrise. 2015 VEX National Championship Match Team 185 Alpha - YouTube
This method doesn’t require any vertical motion, so it’s much more realistic to achieve with a piston. No matter what you decide to use, good luck with your design!