Field Element Shopping List

Hello! Is there an official field element shopping list? I thought shopping lists were provided in the past by FIRST but I can’t find one. Thanks!

I didn’t see a shopping list for everything, but each of the 4 elements has a Readme with materials and cut lists. Playing Field | FIRST

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I put it into a spreadsheet. Assuming I copied it over correctly:

Count Item
3 4” x 4” x 10’ Lumber
22 2” x 4” x 8’ Lumber
5.5 4’ x 8’ x 1/2” Thick Plywood
1.5 4’ x 8’ x 1/8” Thick Hardboard
1 12" 1.5” Diameter Wood Dowel
82 no8 Wood Screws x 2.5” long
60 no8 Wood Screws x 1.5” long
78 no8 Wood Screws x 1” long
26 no8 Wood Screws x ¾” long
2 ¼-20 x 3.5” long bolt
2 ¼-20 Wing Nut
4 50lb Cable Ties
2 3/8” x 4-1/2” Lag Thread Eye Bolt (Home Depot #319949429 or Lowes #1572529)
4 Galvanized Post Cap for 4x4 Nominal Lumber (Home Depot #206059722 or Lowes #1944519)
6 2”x3” 12 Gauge Galvanized Medium L Angle (Home Depot #308149435 or Lowes #1944288)
2 Carabiner (McMaster 3216T41 or similar)
1 Grade 43 Zinc Plated Chain, 1/4" Trade Size – Approximately 108”
2 1-1/4” Schedule 40 Black Iron Pipe 8"
1 Piano Hinge – 14” Piece
8 ¼-20 x 1” Flat Head Bolts
4 ¼-20 x 2” Bolt
4 ¼” Washers
4 ¼-20 Nylock Nuts

I’m questioning why only 3 4x4 for the stage, I think it should be 4. There are three upright posts, and 4 cross bars. The cut list only shows two pieces from each 4x4, so I think you need 3x10ft and 1x8ft to get that last piece.

OMG thank you!

Can we talk about the Team Drawings for the stage?

I think getting this element right and having as much fidelity as possible when practicing will be key to mastery here. The team drawings scare me, in the sense that if more than one robot is hanging from that chain and there is a lot of chaotic motion, that practice element as laid out is gonna move. A lot.

TIG welding aside (and we’ve done our fair share of that, anyone want to buy a slightly used Charging Station?), and knowing that entertainment truss is super-expensive, we have had good success making our own wooden entertainment truss from 2x4s. Critical to success here is a nice big 1/8" steel plate at the base of each truss, 4 vertical 2x4s, and internal 2x4 truss segments made in such a way to prevent racking. We found this to be much more successful than sheathing the 2x4s in two ways- the sheathed truss didn’t age well, and was much more subject to instability as it was hit; also, Internal block sections allowed the truss to better mimic sight lines.

While we’re talking about Team Elements too… We’ll likely be following the GE vs. TE versions for the Source as well. We like the thin profile of the actual element, and we have enough HDPE laying around to mimic the friction coefficient of the slot (okay, it’s a cut up plastic folding table… but hey, slightly textured HDPE is HDPE right?).

Bottom line of this long-winded post is that the Team drawings this year are less than adequate for fidelity in our opinion. More work is warranted by teams to have a good practice experience, if resources, time, and logistics allow.

The team elements are always different from the competition elements in some ways.

Two years ago the climb had a similar problem to this year’s stage. We had to have mentors holding our field model as our robot climbed. We may have the same issue this year. We have to build ours so that we can quickly put them up, take them down, roll them down the hallway through a doorway and store them. For the stage, I’m planning on making the two wings fold together on a hinge and then hanging the trap on it with pegs. So ours won’t even be as sturdy as one built assembled with screws.

We are also thinking of lining some of ours with the same materials as the real ones in places that the game pieces touch.

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THAT was the year where we developed our wooden trusses. So many teams had shield generators fall… and the trebuchet-like TE plans were again, fine, I guess for testing a climb but just nothing like the competition apparatus. I remember seeing makeshift shield generators consisting of one 2x4 for each leg!

Nobody expects the wooden elements to approximate the GE elements to a T. Especially given the restrictions there must be on liability alone. But some are certainly better than others.

EDIT: Maybe the shield generator was three years ago. But we ended up using the same legs for the Hangar for our world championship year in 2022. We had the hangar built week 1 since we just used the shield generator piece-parts. We even used the wooden truss on a parade float before we retired it due to chewed-up verticals after hundreds of robot hits.

Would you mind sharing more information/pics of your wooden trusses? Some cursory googling is telling me that I won’t be able to build a stage out of off-the-shelf metal truss structure for any less than $3000 (conservatively). Weight isn’t really an issue for us, but I’m trying to see if we have any options other than buying a ton of steel box tubes and just welding the entire structure together.

And I agree, this year’s wooden field models are ridiculously bad, especially for the stage. The ones released by REV are actually pretty good as long as you have a large router or waterjet to cut out the plywood pieces, and they all slot together nicely for the speaker, amp, and source. I’m skeptical of the strength of their stage model though.

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Sure thing! They’re pretty simple and built to minimize racking. Here’s a picture from when they were used for the Hangar in 2022:

which was made almost completely from the recycled Shield Generator from 2019:

They’re very simple- the vertical 2x4s are attached to the required heavy 1/8” steel plates on the bottom via two 12” horizontal blocks. The “truss” supports consist of 4 blocks each- two 12” and two 9” in opposing rotation. 8 construction screws affixed diagonally (so they don’t split along the grain) attach each truss support to the verticals. It required a lot of repetition to make our 28 or so truss elements and to affix the 8 screws for each. We made the 4-block assemblies first, then attached them.

This year we are re-making them since ours got so much use in 2022 that our robots just chewed up the legs. We are going very conservative this year and creating all 12 5’ truss segments using 5 truss block assemblies each- one on each end and three in the middle. Luckily we kept all 4 of our steel plates so we only have to buy 2. We will ultimately create the “triangle” in the middle using Simpson Strong Ties and 2x4s. Oh! We are also recycling the polycarb from the Charge Station for the Flap and the central subassembly on a Stage.

I’m posting this in the hopes that anyone creating the Stage and deviating from the supplied GE and TE plans does so in a conservative, safe fashion. We don’t need more Shield Generators falling during practice/scrimmages! Stay safe, everyone.

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I wonder if the field element readme docs are final. There a comments in the cut plan that I am not sure have been resolved:

Our team is building the field on Saturday. I’m not printing out any cut lists or plans until we see if there are updates on Tuesday.

The back upright post is made of two 2X4s cut and combined to accomodate for the back joints/plywood as an alternative to having to cut a chunk out of a 4X4.

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I’m making the following substitutions in our field build:

  • Carabiner → 1,540 lb. 5/16 in. Zinc-Plated Quick Link @ $3.98
  • Iron pipe trap counterweight → the charging station hinge from last season
  • Wood dowel for microphone → 1.25" inner diameter PVC pipe (just about 1.5" outer diameter, and saves a few $)
  • Plywood → Hardboard (in non-structural places where it won’t get hit hard by the robot)

We are adding all 16 april tags to our field build. We’ll build signposts for the ones that don’t go on field elements.

For the record, my spreadsheet is here 2024 Field Build - Google Drive It has notes about the modifications we are making, costs, and Home Depot links for materials.

With the items that I’ve been able to reuse or substitute, the field build will be around $350 for us this year.

We have the same issue with needing to store our elements at the end of each practice.

I’m strongly thinking of just some kind of base, and 4x4 for each side of the stage (& chain between the 4x4’s). With a mentor standing on each base, we should at least be able to practice climb. (I doubt we are attempting the trap, anyway). Someone standing holding upright an appropriate length of old PVC pipe should be good enough for MIC practice.

Truss me guys, you don’t need aluminum!

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To be clear too, we are adding diagonals to each horizontal, well out of robot’s way. Traps are cut, doors ready to be affixed. Each leg is about 50 lbs… each top runner about 30 lbs. and everything is connected via thru bolts- meaning we can break it down in about 5 minutes and set it up somewhere else.

We wanted the top to have the same visual fidelity as the comp element otherwise we would have went with something simple like a 4x4. Also, 2x4s are cheap. Fun fact: no 2x4s were purchased this year to make this and its twin apparatus. All material was gleaned from the previous years’ salvage piles, some dating back to 2016 season. Note to those using old lumber… pre-drill.

1,540 lb. 5/16 in. Zinc-Plated Quick Link have a lip that is just a smidge to large to fit through the chain links. I took them to the grinder to remove the lip on the sides so that they work.

Any chance you could share a rough sketch or cut list? We are trying to decide between something like this and the single panel version.

Each truss is comprised of:

4 2"x4" nominal, (1.5"x3.5"), 60"
10 2"x4" nominal, (1.5"x3.5"), 12"
10 2"x4" nominal, (1.5"x3.5"), 9"
2’x’2’x.125" rolled steel plate (3 needed, one for each vertical truss)

We recreated the triangular truss segment with 6x 2"x4" nominal, 12" cut at opposing 60 degree angles, assembled into two triangles and made into the appropriate shape with three 12"x12"x.75" plywood squares. We were liberal with construction adhesive (liquid nails) in center triangle construction.

We will ultimately secure each horizontal truss further with two diagonals off the vertical legs. We’ll do this when we add the apparatus that supports the trap, and the lower bracing assembly.

Each Stage is therefore roughly 50 2x4s, 3 steel plates, and a smidge of plywood… this is before we start bracing and facing it for the trap section.