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!

Re: The Spring
 

Very helpful. Thank you!

Re: The Spring
 

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

https://vimeo.com/199933366

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

Re: The Spring
 

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.

Re: The Spring
 

... and without ground pickup they will block that lift

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

whoops meant "I'm not implying"

Re: The Spring
 

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.

Re: The Spring
 

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.

Re: The Spring
 

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!

Re: The Spring
 

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

Re: The Spring
 

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

Re: The Spring
 

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.

Re: The Spring
 

I am just wondering where the teams are located that are receiving springs from McMaster Carr. We are in Washington and the response I get from MC is that they will be shipping in the last week of January.

Are you guys from a different part of the country?

thanks

Re: The Spring
 

Re: The Spring
 

Here's our spring testing video: https://www.youtube.com/watch?v=I4XiDYRmNRE

Re: The Spring
 

We bought springs within the hour after kickoff and got ours last week. I assume people who ordered later in the day/weekend are getting theirs now. If you didn't order until last week you're probably not getting one for awhile.

Re: The Spring
 

Ordered on Sunday of kickoff, still ~1week out

Re: The Spring
 

Hi Bob

Miss being in the PNW.

We ordered at kickoff and got it today. We went for overnight, not cheap, but it took a week.

Re: The Spring
 

We have ours and have found that it is in fact very flimsy. We initially thought it was only a spring instead of a rod to prevent robots from breaking it by running into the side, but now we think that the gear must be all the way "on" to stay on the spring.

Re: The Spring
 

Justin,
I do not have a video yet, I will get one posted but we ordered the spring 3 of them 36in each from Essentra Components. All of the spring characteristics match the spring provided in the game manual, but it does look stiffer than what you have posted. I will try and recreate what you did tomorrow at our meeting and send you some videos. If you want I can also give you some of this spring and we can compare the ones you have and the ones we do.

I am also really interested in the difference!

Re: The Spring
 

Point of reference for those waiting on the McMaster Carr spring. I ordered ours the Monday after kickoff. It shipped out of the Atlanta wharehouse yesterday.

Re: The Spring
 

Our McMaster one came in today. I took it over to the Robonauts so we could do a direct comparison between the century one they got with identical specs to the mcmaster one as far as I can tell (https://www.mcmaster.com/#9664k68 vs http://www.centuryspring.com/extensi...ings-e-41.html) They behave very differently.

Foreground picture is the century one, background one is the mcmaster. Heading over to FIRST Q&A now to ask if they're only going to source the spring from McMaster. Aw man, just missed being the cheesy poof question: https://frc-qa.firstinspires.org/qa/255

Re: The Spring
 

Seems like the pilots will need to be careful with how they lift the gears. A gear which is decidedly "on" the spring when the Pilot starts pulling could easily bounce off.

Re: The Spring
 

Wow. That's really helpful to know. Though another thing to consider: While at the beginning of the season all the springs may behave like the McMaster spring, by the time champs rolls around, it may be an entirely different story. A Lift spring that has become damaged will hopefully be replaced. But a Lift spring that has become slightly stretched out and more likely to drop a Gear? We can be sure they'll still be in use.

Re: The Spring
 

We have a local spring manufacturer that offered to send us a couple for free... will post a video of our results when we get those to compare to century and mmc.

It looks like there are a few different ways to mount the spring (peg, something with screws, shaft collar?). Has anyone tested the shaft collar?

I remember reading that spring manufacturing tolerance is +/- 10% for the k value. Is there some math that determines how this affects the "bendiness" of a spring? How would one even measure the "bendiness" of a spring?

The field drawing specifically calls out a 1/4" long rod (like 0.625 OD or something) that the spring very snugly fits over. The tour video shows a shaft collar not called out in the drawings. I asked about the shaft collar in my question on frc q&a

Sent from my SM-G930T using Tapatalk

Re: The Spring
 

Have you tested the "initial load" "Minimum Load" of these, or the spring constants? Those would shed some light on the different behavior.

Re: The Spring
 

The initial load of the mmc spring is almost 25lbs, while the century spring is only 22lbs (according to sites). That might be a significant factor when combined with manufacturing tolerances.

Also the century spring seems to be carbon steel, while the mmc one is spring-tempered steel. Not sure what the difference is really though.

Gear peg spring stiffness
 

Our spring that came in was much less stiff than we had assumed. I am not sure how far off from the true spring it is (got it locally, very similar but not identical dimensions).

But, as a practical example, our gear falls off very easily if it is not put down at the very back of the spring. Anyone see this behavior as well? Anyone have the real McMaster part and have practical examples of how to get the gear on without slipping?

Re: Gear peg spring stiffness
 

Re: The Spring
 

I've merged a couple of threads on this topic.

Re: The Spring
 

Andymark has them in stock now.http://www.andymark.com/Spring-p/am-3557.htm

Re: The Spring
 

Does anyone know if these are sourced from McMaster or somewhere else? It seems springs with supposedly same specs are significantly different. Being AndyMark, they'll probably be the ones on the AM fields for districts, so hopefully it's the same source as FIRST.

Re: Recommending "Hidden Figures"
 

What I want to know is, if you drive into it and the tip of the spring hits one of the spokes of the gear, will it flex/deflect into one of the open spaces on the gear to allow for a successful hook or is it rigid enough that it acts like a solid dowel?



EDIT:

That merge really threw me off, I swear there was only one reply to the thread I posted in when I hit "Save".

Re: The Spring
 

Emphasis mine

Re: The Spring
 

I'm sure that's simply to play CYA if the springs end up being different.

Re: The Spring
 

Re: The Spring
 

We have about 300 of these "similar" springs. We have one of the McMaster springs. This spring is stiffer. The od (7/8") and the wire diameter (0.135") are both the same as the McMaster spring, but the spring rate is higher. We had these made in Logansport at Myers Spring. It's not a standard part for them, but they can make more.

The reason why we started listing this spring is for international sales. International FIRST teams have a difficult time purchasing from McMaster, from what I hear.

As for "AM fields for Districts", this is definitely not the spring. The field-specific items for Steamworks comes from FIRST, not AndyMark. Both the Districts and Regionals receive approximately the same Steamworks items.

I will set up a display much like what ahartnet did in a previous post to show the difference.

Sincerely,
Andy B.

Re: The Spring
 

QFT. Maybe FIRST can remember that for field pieces next year.

Re: The Spring
 

Here are pics showing an AndyMark spring with a gear and a McMaster spring with a gear.





The McMaster spring deflects 1/2" more than the AndyMark spring, under the same load of a 10 tooth plastic gear.

Sincerely,
Andy B.

Re: The Spring
 

Interesting that your McMaster Spring seems to deflect more than Ahartnet's does. One manufacturer listed a 10% tolerance on the spring rate, is it possible (probable?) that all of these springs are within tolerance and we could see a varying amount of stiffness at competition?

Re: The Spring
 

Is there reflective tape on the spring / peg?

Re: The Spring
 

The barb is black. There are reflective targets on the back board. The rules manual is your friend.

Re: The Spring
 

Check section 3.13 on page 37 of 126.

yes - there is 2" by 5" tape on each side of the peg. more dimensions for H&V placement in the game manual.

good luck..

Re: The Spring
 

It is very probable.

It is also very probable that the spring rate will change as the regional / district event goes on.

I would state that teams should EXPECT the spring to be different (hopefully within reasonable tolerance).

Re: The Spring
 

We ordered ours at 3:36pm on January 9th, I just checked, and it's been shipped as of 5 minutes ago, expect tomorrow.

Re: The Spring
 

I ordered on Sunday morning after the kickoff. Latest from MC is that it ships "next week"

Just got ours in from MC today (January 24th, Tuesday)
Anyone in the Seattle area that needs one of these please contact me....I have some extras

Re: The Spring
 

Team 747 just received the spring today. we are only going to use 12". If anyone could use the rest just send and address and we will ship it out free of charge.

George

Re: The Spring
 

Team 5547 could use the remainder of the spring. IT would be greatly appreciated!!

311 N. Washington
Hale, MI 48739

Again thank you
The Talons

Re: The Spring
 

Are you guys going to use all 24" of that spring? Team 3630 would really love to have 12" if you don't want all 24". DM me if you have any extra.

Re: The Spring
 

My question was answered on FIRST Q&A. There is a collar on the spring (and field drawings are being updated to show that, and all field springs are being sourced from McMaster ( https://frc-qa.firstinspires.org/qa/255)

Re: The Spring
 

You guys going to use all 12" of what you get? My team would love a spare quarter inch or two. Then we'll just need 47 more teams to agree and we can easily build our own Franken-spring.

Re: The Spring
 

At what point is your spring more welding rod than spring?