Slip Gear Puncher

VEX V5 General Discussion
#1

So we made a prototype of a slip-gear today, since our working model broke due to a faulty stopper. I’d like to get some suggestions on the following questions.

  1. What’s a good way to stop the slider
  2. Is direct drive or geared drive better for the slip gear? We are running speed motors
  3. I’ve seen some very fast punchers. If anyone has knowledge on how this is done full-field, we’d like to use it on our puncher
    (Pictures are appreciated! We’d love to incorporate other ideas.)
#2
  1. We use braided string, and a nut and bolt on the linear slides to stop the launcher
  2. If you want your launcher to be fast, use direct drive.
    3.Use 4 inches of linear gear to make your launcher fast
#3

Thank you for the input! We’ve seen various view points concerning the braided string as a stopper and we have a few questions:

  1. Is the string the only stop, or is it auxiliary?

  2. How often does the string need to be replaced? In other words, can we depend on it throughout an entire tournament?

  3. If it is not the “secret sauce” of your robot are you willing to share just a picture or video of how the braided string stopper works?

We fully understand you wish to keep any details confidential.

**just one more question: What sized slip gear works full field for you?

#4

I can upload some pics for you tomorrow at school. The string is a stopper as well as a screw and nut on the stationary part of the launcher and on the slide that moves. You should be able to use one string throughout an entire tournament.

#5

How do you keep the string from getting loose? We use nylon as string and it will get completely loose after only around 32 balls

#6

Same, we’ve tried a few knots, but not even the vibration proof hitch is working.

#7

@Samuel Crouch (7842D) did you try 7842B’s approach? that is use spacers at the rear of the launcher to provide a “cushion” that absorbs some of the shock. we have yet to have a problem with it coming loose.

#8

Yes.
That’s not the problem.
Our knots come a little more loose every time we fire. even with knots that are designed to do the opposite. There’s just so much force involved.

#9

I’ve seen teams use a bunch of solid Teflon spacers in a row, foam on both sides, or lots of friction mat. The general idea of a stopper is to a.) distribute the force as evenly as possible along a large surface area and b.) provide a cushion of some sort so that the puncher doesn’t get damaged. For this reason, I would recommend foam.

To increase the fire rate, 3-4 high speed motors should do the trick. A high speed motor turns at a little over 2 revolutions per second, but of course this theoretical speed is decreased quite a bit by rubber bands. So, like @4361T said, direct driven should work fine. Depending on how much you reduce friction and how many motors you use, your fire rate will likely be around 0.5 - 0.7 seconds.

Good luck!

#10