The Spring

Finally got our spring today. We cut it to length and thought we’d share our experiences / images so other teams could find comparable items since FRC has a habit of cleaning out worldwide inventories of things.

We found the spring deflects about 7/32" when the gear is placed on the end. Here’s some pictures: http://imgur.com/a/FGELI

It’s pretty stiff and holds the gear, even when it’s on the very end. Good luck teams!

Very helpful. Thank you!

We got our spring in as well. See link for video showing it is in fact “springy”

This is an E-41 spring from Century Spring cut to length. Specs match the McMaster p/n supplied. (http://www.centuryspring.com/extension-springs-e-41.html)

It is sitting on a spring post made per drawing with exception that the diameter is a tad undersized as the diameter called was difficult to get in the spring (calls for 0.66" when spring ID is ~0.60 )

On that note, the drawing doesn’t specify at all how the post is attached to the carriage. I can assume there’s a 1/4" bolt and nut holding it in place, but this isn’t shown. We also came across the attached picture which shows a clamping shaft collar which isn’t shown in drawings or field model. Frustrating when you’re trying to make field elements as real as possible.





We have had the same results as Justin when testing our spring. We foresee a lot of teams missing this part of the game. If teams follow most of the RI3D designs many teams when placing the gears will have them drop to the floor.

… and without ground pickup they will block that lift

Hey, is that the real spring that will be used in competitions? If so is it possible for you to post a video of your spring and the gear being put on the spring in different ways. There is a huge debate in my team about the springiness of the spring, and I’m sure other teams are in the same situation. We’ve ordered the spring but it will be while before it gets here.

We have the real spring, if you tell me what your looking for or if anyone else is questioning something I could post a video in about a hour but probably a little longer.

I agree that this would be a huge help. Justin’s post above was a bit troubling considering the amount of bounce the gear will receive if placed on the end, or even dropped on the middle for that matter.

Isn’t that exactly what Justin’s post above shows?

As Justin mentioned in his post, the spring shown in the video he posted matches the specs of the McMaster-Carr spring used on the official 2017 fields.

Replicate EXACTLY what Justin Ridley did in his video above. I would love to see how the spring behaves when subjected to a gear dropping.

That’s what we are looking for too. I’ve seen evidence of teams with springs like Justin Ridley’s and teams that claim their springs are opposites of that. We just want to know what the springiness of the *actual *gear is.

I’m still not sure because some teams are claiming that their spring is complete opposite of what Justin’s post showed and we just want to be sure. Hence asking for a video of the real spring that will be used on the field. No offense to Justin, but this spring has become extremely shrouded in mystery.

I’m still not sure because some teams are claiming that their spring is complete opposite of what Justin’s post showed and we just want to be sure. Hence asking for a video of the real spring that will be used on the field. I’m imply that Justin’s post is wrong, but this spring has become extremely shrouded in mystery.

whoops meant “I’m not implying”

Hey Jalaj, I have the spring that matches the field part right now. I am cutting it down in to separate pieces that match the field size tonight and will be leaving one of the pieces at FIRST Chesapeake Command Central in Mechanicsville tomorrow some time after 10 AM. I’ve already given out the rest of the pieces to teams outside of the city (need to meet a guy halfway between here and Charlottesville tomorrow or Friday to play the hot potato game) but 384 should definitely head over to test it out for themselves if they want some hands-on time with it if y’all get a chance.

I agree that it’s concerning that droswell’s pictures seem to indicate little bounce (though they’re static images of a static load) while Justin’s video of a spring with identical specs shows that if the gear doesn’t get placed at least halfway into the spring there’s a good chance it’s coming off, and if you knock the spring as you’re placing it it might come off too. I hope it’s not just due to a wide tolerance in the manufacturing of the spring.

I think this would also make me weary of any strategy that is dependent on a totally passive gear manipulator - where the human player is lifting it out of the robot.

I’m all for some video of a “McMaster” spring. If springs folks are getting from other sources behave differently, I’m sure we all want to know.
Thanks!

We’ll put together a video shortly and post it.

We received our Mcmaster spring last night and have not mounted it yet. With just playing with it, Would say the video is reasonable.

Here are some pictures / videos from 319 playing with the spring at kickoff. Not sure what to take away from it, but the spring at kickoff seemed much sturdier than the one posted above.

4 GEARS on spring.

Dropping a loaded spring from ~2ft.

Some big oaf bending the spring by hand.