Release Mechanism

[rwkling1]

I have looked for a thread or posts on this on CD, but I haven't found any yet, and if someone could post a link that'd be great, but how is your team releasing your shooter? I've heard some different ideas, but what is your teams plan?
Thanks!

[joelg236]

Standard way (from what I've seen e.g. Ri3D) is a sprocketing winch with a dog gear to release.

[cadandcookies]

There was also some interesting discussions on using a gate latch and pneumatics for a release like many teams apparently did in 2010, or shifting to a neutral gear from an existing shifting gearbox.

[Dan Richardson]

Team Ri3D 1.0 used a one way drive quick release gearbox on our 3 day bot. We uploaded the cad for the gearbox here: http://www.robotin3days.com/ri3d-1-0-winch-shift-to-neutral-ratcheting-gearbox/

Robby talks about it during the 3 day build here: http://www.youtube.com/watch?v=SWO9OE8JZZk&list=PLpJRpRT0xvIgKI1JFG1EBsIGLxVsJdhL5&feature=c4-overview-vl

We are also doing a sort of CAD tutorial on it's construction as we were pretty happy with it. That should be posted tonight.

There are other forms of release mechanisms but this design worked well for us.

[Ether]

I really like the over-center linkage that Team JVN used, if your team has the resources to make it.

http://youtu.be/Gm96S8gdhR0?t=3m2s

[rwkling1]

Thanks for the replies!

[Jibsy]

I have looked for a thread or posts on this on CD, but I haven't found any yet, and if someone could post a link that'd be great, but how is your team releasing your shooter? I've heard some different ideas, but what is your teams plan?
Thanks!

The above mentioned options are all good, but they make it a bit tricky to have multiple launch settings.

We're looking at using something like a volleyball crank with a pneumatic piston to release the lock. This means you can draw it back as many or as few clicks as you like.

Hope that helps!

http://epicsports.cachefly.net/images/40767/300/porter-volleyball-net-tensioning-winch-w/-hardware.jpg

[Ether]

The above mentioned options are all good, but they make it a bit tricky to have multiple launch settings.

?? Ri3D 1.0 has a ratcheting winch which can be programmed to stop at any point and be launched from there by disengaging the dog clutch.

[Alan Anderson]

I really like the over-center linkage that Team JVN used,...

The Team JVN "choo-choo" mechanism is essentially the same as the catapult wind-and-release used by the TechnoKats in 2006. It's very repeatable and reliable. (It's just a whole lot slower than we needed for a dominant robot that year.)

[rwkling1]

The above mentioned options are all good, but they make it a bit tricky to have multiple launch settings.

We're looking at using something like a volleyball crank with a pneumatic piston to release the lock. This means you can draw it back as many or as few clicks as you like.

Hope that helps!

http://epicsports.cachefly.net/images/40767/300/porter-volleyball-net-tensioning-winch-w/-hardware.jpg

quick question on the volleyball crank. When you press the release, does it have to spin the handle (which would be mounted to a motor) to be released? because if it has to spin backward, it wouldn't quite get all the power since you would be spinning the motor simultaneously.

[Dan Richardson]

?? Ri3D 1.0 has a ratcheting winch which can be programmed to stop at any point and be launched from there by disengaging the dog clutch.




This is correct. Ri3D 1.0 actually ran an encoder on the cluster shaft. We accomplished this by drilling a .249 hole into 3/8" hex shaft and pressed in a dowel pin. We then mounted the encoder on an encoder block.

Before the ratcheting wrench was installed, the encoder provided the necessary feedback to hold the catapults position.