Ball Puncher Fitting

[bEdhEd]

Originally Posted by AdamHeard

You can't really ask a question this vague w/o posting your geometry for others to play with.

Otherwise, you get an answer like Damprobot said. Play with it until it fits. Switch off and on different constraints to get a feel for where things want/need to be. It's an iterative process for sure.

It's also sometimes nice to save the sketch you have, and give it to many people on the team. Tell them "make it fit", even if no one solves it, their iterations may inspire the eventual solution.

Sorry for not posting any pictures of my model. I was unable to at the moment, but we figured it out now, so there aren't any problems. When our CAD is mostly done, I'll post a picture.

[RRLedford]

Team 3135 has finished our linear ram shooter design. We came close to abandoning it in favor of a catapult approach, but we finally determined what was undermining our performance results.

It is all about the ram speed, when the ram travel is limited. Yes, the no protrusion beyond 60" vertical limit means a tougher challenge for a ram design.

We are using surgical tubing 5/8" OD X 1/8" ID and both pre-stretched ~6" and then full power stretched to 3X initial length. Our ram travel is about 11" Our entire mechanism will be under 30" length.

We started out with too massive a ram and thought developing some ram speed before it hit the ball with good tip penetration before losing contact with the ball would help, so we left a gap. This was so wrong.

We now use a 4" Omni wheel as the ram tip for contact with the ball and our ram is 20mm Bosh t-slot framing ~24: long. The ram slides on a 2" X 1" length base element of 80/20 t-slot frame with a linear bearing block based on this SUPER useful nylon accessory item:



Every FRC team needs to have a dozen or more of these on hand at all times.
They are a fantastically easy way to implement smooth, precise linear motion on your robot using off the shelf 1 x1 aluminum framing.

I will be posting a thread on our shooter soon. Our gate latch trigger also slides behind the ram on another slider block that a very low RPM output gearmotor winch winder retracts. After shot is triggered, winder reverses and trigger block is pulled forward by thinner light duty surgical tubing to reengage with rear of ram. Winch then pulls both back to whatever desired shot power level we want, stretching out the surgical tubing accordingly.

-Dick Ledford