Practice Field

When people build not entire field but like the main pieces out of wood for example, the vault, switch and scale, how is it done. Like what wood is used how long does it take etc and is it worth it?

There is a link on the First Website under the game and season materials that has plans and diagrams.

As for your next questions, “How long does it take and is it worth it?” That depends.

We usually find that it is worth it to build the field elements that we are focusing on, but sometimes the wood versions do not behave in the same manner that the actual field does. Depending on the game and if you choose to build all of the filed elements it can be fairly expensive and take a good amount of time.

All the materials are listed in the “team versions” of the field element drawings (in fact, they provide a pretty complete bill of materials for you). Typically there’s a lot of 2x4s and plywood used for most elements.

As far as time, it depends entirely on how many people you have working on it and how tight you hold to tolerances.

I’ve seen teams who get a small army of people and assemble all the main field elements in a single afternoon (some even have them done the day after kickoff). I’ve also been on teams that don’t finish their first field element until week 5 (only to discover they made the completely wrong drive system choice 5 weeks earlier).

In general, I think there’s a huge benefit to getting field elements built as early as possible, since it helps with prototyping, calibration, and later, practice. That said, like with all things in FIRST, you have to work within the capabilities of your team. In you have enough people, building field elements can be a great task for mechanical/assembly students and mentors who aren’t interested in the design phase of the build, but if your team is small and doesn’t have the resources to spare, you might be more selective in what elements you build and they might take a bit longer. Sometimes this is also a great opportunity to get parents involved, since many (at least in my experience) are happy to help cut wood for a meeting or two.

–How is it done

Quickly, and with precision. In recent years drawings have been published for dimensions on representative mockups of key field elements. Example: Buyer beware, not all functionality is represented (see 2017 climb/rope setup)

–What lumber is used

Whatever you have around. Or from the local big-box home store. Really, any lumber will do, as long as it meets the dimensions. Construction screws, a circular saw, maybe a jig saw, and a power drill will probably be all ya need.

Usual “good lumber” things apply - straight, dry, not super expensive… don’t buy outdoor rated lumber unless you want to keep your field elements outside in the rain (?).

Bricks or Sandbags are very useful too for keep things from moving.

–How long does it take

Depends. How good is the person assembling it?

We had a professional carpenter (parent turned mentor) do it one year. Small elements were completed in a matter of hours. Less experienced folks might take a couple days.

The switch was a big thing this year, that alone might take a few days.

Really just depends on the size of the thing, and the experience of the builder. However, assuming someone is dedicated to it and FIRST HQ doesn’t throw anything super complex at us, I’d be surprised if they couldn’t crank it out in a week of evening meetings.

–Is it worth it

It is imperitive for any team that desires to be high-performing to have access to a practice field. If you didn’t have at least mock-ups of the field elements, I’m not sure how you’d test your robot (other than in your first match, which is generally not the best option). It’s easy to do (just follow the prints given). Anyone with basic hand tool experience can do it. Yes, your team should do it. Get some parents to work on it in the background so it doesn’t take time away from robot design.

First always has a “team” field version. How close it is to the actual field version varies year to year. The closer you get to the actual field the more effective your practice will be. But has others have said, you have to within your budget.

As with all things FRC, it depends on your situation. In our case, we have three mentors* build these things. This year, two or three of them worked each Saturday in build season** to make an exchange, a scale, and a switch fence. Because we were behind on the robot, we didn’t get very much drive time, so this year’s efforts might have been better spent in other things. If we had did drive practice with them as in previous years, it would have been worthwhile. The main thing here is to sync up with the robot design and build team, and build pieces according to the priorities that the drive team will need.

  • But they didn’t get to do much mentoring this year.

** They had rather minimal equipment for this endeavor. We looked into a panel saw, but realized we don’t have anywhere to store it. I think I’ve figured out a portable plywood cutting table that should help next year. As it happens, we’re doing a dry run with this table today converting a golf cart into a Mardi Gras float with air cannon.


Absolutely. Look at the dimensions that matter to you (the parts your robot or the game piece interact with) and get those right. The actual field doesn’t always match the drawings either, but this is the best you can do short of going to Manchester for kickoff.

From a programming standpoint, having a practice field (or half of it) can be very useful for testing autonomous, doing driver practice, etc.

As mentioned above, there are some differences when you build elements from wood. For example, we had problems with the “bounciness” of the scale – we found the scale on the real field at competition to be more “bouncy” and therefore had some problems with some cubes falling out during auto.

However, I definitely think it’s a worthwhile investment that will help tremendously if you have the resources.

We are lucky enough to have a full practice field, but this applies to individual pieces as well.

We’ve learned over the past few years that if you have the ability its always worth it to use the official field drawings to engineer your own “team” versions.

Too often are the dimensions wrong (ex. the climbing bar on the scale this year) or are challenges misrepresented (ex. the davit from last year and visibility of the switch fence cubes this year).

When we already need to cross-reference the field drawings to ensure accuracy, it just makes more sense to make our own.

(we used the team versions at first this year, then changed to our own scale ~week 4 of competition)

We built the field this year. It was about $650 in lumber, glue, and screws and a week and a half of thee adults and a couple students working on it. It was really a lot of lumber and a lot of cuts this year. None of it was particularly difficult, but it really took some time. The saw horses, table saw, and circular saw were all used quite a lot. A track saw probably would have been helpful. Having a large space to build this stuff and a large space to store it is important. We got an additional 20’ cargo container to store material which was helpful, but it wasn’t enough to store all the pieces once assembled. I think we saw the benefit from having it to practice with, and we’d probably do it again.

It is very worth your time and effort to build the field elements that your team will be interacting with. Note that this does not necessarily mean following the drawings provided by FIRST. The team I worked with in 2013 was only going to climb on the lowest rung of the pyramid so we only built something to approximate just one lower rung and did not bother building the rest of the pyramid. The only dimensions we used were the diameter of the rung the height from the floor.

As Gus noted, be careful about the resources you allocate to building the field elements. A friend who mentors a local team said that many of the main mentors for his team focused too much on helping to build the field elements and the team members and other mentors building the robot “lost the plot” and diverged from the strategies they chose after Kickoff.

While the links to the field drawings and bill of materials are intended to be helpful, they should come with a bit of disclaimer.

The drawings that FIRST publishes are next to useless for actually building the field out of wood and the bill of materials is usually 20-25% higher than it needs to be because FIRST does not publish layout drawings or even consider a cutting plan.

I’m sure the engineers who produce the drawings are quite competent engineers, and follow good engineering practice… but they clearly aren’t cabinet makers, and really don’t seem to understand (or aren’t given the time) to figure out how someone might actually cut the plywood and lumber to create the parts they have designed.

For the past couple years I have produced cutting diagrams and shared them here on CD. This is a link to this year’s thread…

It would be fabulous if someone… anyone… talking to the FIRST HQ team could get the practice field design team to actually try building a field using their own drawings. (And then try it again starting from a cutting plan!) I’m sure if they did that, then they would be able to understand the importance of the cutting diagrams and produce them as part of the official field package. It just saves SO much time and reduces so much waste wood to start out with a plan!

So… anyway… there are drawings, (and they are wayyyy better than they were 10-15 years ago where there were many errors and examples of poor drafting practice) but to actually make them useful and efficient requires about 8-10 hours of AutoCAD work.


+1, field drawings are great but still require sensible construction. Make the parts of the field match the necessary measurements and ignore the other measurements in favor of structural integrity. It really helps if you have mentors and/or students with woodworking experience, and also helps to have awesome resources like the one Jason linked above.

This can be a way to draw in new mentors and team members who “don’t know anything about robots” but have built a deck on the back of their house.

Last question first: Is it worth it?
Answer part 1) You have to consider the fact building field elements will take resources: materials, drawings and labour. The answers above provide a disclaimer as to the limitations of the field drawings provide by the GDC. Also, those resources you will assign to the project will not be available to do other tasks. So, you may want to wonder if there are outside resources that could be called in to help, the earlier in the build season the better to support prototyping, design, build and calibration tasks.
Answer part 2) You must wonder whether you need ALL field elements. The answer to that one will depend on your game strategy. If you intend to build a “low game” robot, any investment in the taller/higher field elements will not serve much of a purpose. You may also not require to build a complete field, but perhaps only half a field. This should be one topic on the first things to-do list at the very beginning of the build season;

Second question: How long and when?
Answer: If the field element build is going to take more than a week, considering the entire build season is only 6 weeks, you should wonder whether you really want to do it, IMHO; Following your team strategy session, you may be able to identify what field element may be need to support prototyping, design and calibration tasks and when in the build season you need to have the element available. Don’t forget this exercise will take resources away and you don’T want that to jeopardize other, perhaps more critical, tasks.

First question last: What materials?
Answer: Those field elements will only serve for 2 or 3 months and not suffer the abuse of full competition repeat games. Materials should be inexpensive yet of good enough quality to make the elements sturdy enough and useful. Plywood and standard 2X2, 2X3, 2X4 boards should suffice;

My two bits…

Is it worth it building the elements?

Well some of them. Most of the time. Often you can mock up something simpler than the official design that will suit your purposes just as well. Choosing what, exactly, you want to build and what aspects of it are critical is part of an iterative process that will take place as you plot out your game strategy for the season. Last year, for instance, if you were going to focus on the vault and low beam, you didn’t need to build the high beam. If you were going to focus on the high beam, then you probably only needed one side of it… and could perhaps build a platform that attached was braced by a wall in your shop rather than an entire scale. Or balance. Or whatever the high goal was called. (I don’t get too into the official terminology any more…)

On the other hand, having the full scale replica around can help give a sense of the size and can sometimes identify unusual quirks in how the field elements are going to behave. Like everything else, you’ve kind of got to do a cost/benefit analysis to know what is right for your team.

Since I’m no longer a coach, but rather a kickoff coordinator and field builder, I try to have all the parts ready to go at the BC kickoff. (Field builders gain early access to the drawings, subject to a strict NDA… and we have no information on what the parts are going to do or what the game piece is. So I figure we have to pretty much build all of them since we don’t know which ones will be the most significant.) We have students assemble them right there, and then distribute the parts to the teams. That way everyone gets to see the “real” thing once and have a better idea of what they will need for optimizing their build season… and some of them start out with a field element right on day one. I’m still evaluating the return on investment for that… it adds a bit of pizzaz to kickoff day, but not without a considerable amount of volunteer time in the week leading up to kickoff. If you’ve got a kickoff coordinator near your team, and some volunteers who aren’t closely attached to a team (and just happen to have access to a wood shop) you might be able to talk to them about doing something similar.


Please be very careful with the bold. Had someone place a support on the Rungs this year in such a way that at least one team at a pre-bag event stated that they could not climb, at all, at that event, even though they were designed to be able to climb on the competition field.

It’s surprising how many “necessary measurements” can be overlooked…

The better translation is: If a robot can interact with it directly, build as close to spec as possible. (Using wood instead of metal/lexan, obviously–unless there’s a performance issue noted on CD in which case get some THIN metal/lexan for testing.) Otherwise, make it strong enough. A prime example is 2014’s Truss–for testing, two ropes/PVC tubes/aluminum rods/anything long stretched at the right height would be near-perfect for “we’re not going to run into this” or “we can throw over this”. Not “build this box of plywood and 2x4”, but “Gimme that rope!”

Also, know what you don’t need extra of. Teams didn’t need to build the Portal and the Exchange this year, if they build the Exchange they had a Portal too. (Just migrate it from side to side to center as needed for practice.) In 2016, teams didn’t need to build ALL the Defenses, just the ones they planned on going over.

This is exactly what I meant about the field element group staying synced with the robot strategy. Unless you’re making a full practice field for multiple teams, build the field elements your team needs, focusing on the dimensions which are critical to your application. If your robot is built in phases (e.g. phase 1, we’ll work on task a and b, then add task c in phase 2 and task d in phase 3), build the field elements needed for tasks a and b first, then c, and then d.