Puncher help (specifically 574c

So on our puncher we have 1 100 rpm motor pulling back 8 rubber bands (4 on each side) the motor bruns out after around 20 shots (we have v5) what are some things we can do to fix it. (574C inspired us at the night at the museum signature event on sat and we have a competition on sat so we took apart our double catapult and started building this but we are having trouble. That’s the backstory. 574c if you remember we were the volunteers that stalked you.

gear ratio, use a 12 tooth pinion (motor) to a larger gear (slip gear)

or, with my puncher, we can hit high flag from full field, and more (in the event we fall out…) we have two high speed v5 motors with 3 blue (im not sure of the brand, dm me tomorrow and ill try and remember to check) rubber bands on each side

our team only needs 3 on each side to hit the flags have you tried that ?

Ya but it turns it halfway only

@dchoi77 Did you follow their tutorial or did you design your own ?

I followed the tutorial and made little changes like number of teeth on slip gear

Did you add lithium grease ?

I don’t have any but a team member of mine is bringing some tomorrow at practice

That might fix it. Try to reduce the amount of friction the slide has to encounter.

Ok thanks I will let you know after I try it tomorrow morning

You could try going down to 3 rubber bands on each side and stretching them out more that might work to stop your problem with burning out

Hey! The guy from 574C you were talking to Saturday.
Some easy tips to improve your puncher:

  1. Make sure the puncher is lubricated and that the slide moves freely.
  2. Move the standoffs that hold the ball as far away from the puncher to increase the amount of momentum the slide rail gains before striking the ball (in the tutorial I put the standoffs 1 hole too close).
  3. Make sure the rubber bands run parallel to the slide rail.
  4. Reduce the number of rubber bands (full field shooting is overrated anyway) we use 5 total, 8 bands is overkill.

edit: also don’t do a gear ratio, a 1:1 the puncher should be able to hit the top flag from the back starting tile with 6 bands or less if you get your angle right

Should we use the same number of teeth as you guys used in your tutorial? We shaved 3 more.

Shaving those three teeth means that it pulls less overall. This required you guys to put more rubber bands, and which therefore, meant that you burnt out alot more. Probably better to follow the tutorial exactly if you want duplicate results

You want to maximise the number of teeth on the slipgear. More teeth means a longer drawback distance, long drawback means more power, more power means less rubber bands needed, less rubber bands means the motor doesn’t struggle as much.

3 teeth doesn’t sound like a lot, but it could be the difference between toggling a flag and only half toggling.

1 Like

Do you have any recommendations for a team using the “v4” cortex system? We have a 1:3 gearing and we run 6 bands but what would you recommend? It currently takes it a total of 2 seconds to pull back.

@dferguson10 Try reducing the amount of rubber bands. We use 5 on ours and it worked on a 1:1 cortex motor. Just make sure the cortex motor is 100 rpm.

The girls followed the 574 video pretty closely but drive the 36 tooth skip gear with 2 torque motors, rather than 1. I think they have 4 rubber bands on each side. Lately they have been having trouble with the unit not shooting as far, and sometimes it just doesn’t make it all the way back when retracting. At our last event we were talking about taking it apart and checking for issues, and probably need to realign and relube it all.

We also have noticed that after a while, the rubber bands need to be replaced. They get weak after a while and don’t fire it as far as it should. They have had no trouble shooting from behind the platforms.