FRC 95 2018 Build Thread

We’re starting a little earlier than in previous years for a few reasons.

First, we would encourage other teams to start their own build threads! We’ve learned a tremendous amount and helped a large number of teams with our build threads. More must be better, right? Please consider publishing your own build thread, we’d love to read it!

Second, I’d like to share a few things about how we approach kickoff, rules, and brainstorming before it actually happens.

In the last couple of years we haven’t been treating the rule book as a set of “rules.” Instead, we’ve been treating it as a product definition manual. This does a few things for us. It puts us in the mindset of working with FRC rather than against them. Just like working with a customer in the professional world, it has been beneficial to approach the FRC product definition manual in a constructive mindset and not an adversarial one. It can help with justifying those occasional weird rules (it’s what the customer wants) and explains a large number of other rules. When asking questions of the product definition manual it’s about clarifying what the customer wants so that we can make a better product, not seeing if we can exploit some twisted version of what is written.

As a side note: I’ve started writing product definition/requirements documents like FIRST rule books at my job and it has been tremendously effective. Vendors like the style because they get maximum creative freedom to solve the problem, and my bosses like the style because the problem gets solved.

During kickoff and the few days afterwards we talk about ‘how to play the game’ i.e. what functions should our product have to meet our customer’s requirements. Like 1678 notes in one of their many excellent videos, there is no discussion of ‘how’ things are done, just ‘what’ things are done. We assume that no matter what we chose to do we can figure out how to do it later. This has proven to be a good assumption.

We then use a weighted decision matrix to pick a particular strategy. I won’t go into how a weighted decision matrix works, that’s been done ad nauseum by numerous great sources. We consider categories like scoring ceiling, growth-over-season potential, technical difficulty, independence from alliance partners, and rarity factor. We aim to go for a competitive design, but with some sort of creative twist or feature that few other teams have. This has usually guided us well in selecting the right strategy to pursue.

As for how our build will go this year, we have on-boarded our first fabrication sponsor in many years, if ever: Progressive Manufacturing in West Lebanon, NH. They do phenomenal sheet metal work and will be making a majority of our sheet metal components this year, freeing up our time to test, develop, and design. We have a preseason chassis with components made by Progressive MFG that I will be publishing soon.

Thanks for reading!

Hyped for this. By far one of my favorite things to follow each season now. Best of luck! Extremely excited to see you guys at granite State!

Neat.

It should also be pointed out that we’ve decided that, for moral reasons, we won’t be using 1/2" hex shaft, or hex of any kind, in this years robot. In fact, just to avoid the appearance of impropriety, we won’t be using hex head bolts or socket head cap screws. Wing nuts and Phillips for the win.

Every team is different but, for us, we feel it’s important to make a stand.

Could you go in more detail as to why? It’s an interesting stance to take.

Hex shaft privilege is something that Andy feels morally opposed to. The gentrification of drive styles in FRC put Andy’s dad out of business as a keyway maker.

While we all digest the new game, here are some pictures of our pre-season drive base project.

Our initial points analysis and strategy analysis is done. We anticipate changing most or all of the numbers in the next few days as we brainstorm and rethink everything.

I really love the weighted analysis by idea/archetype. Are you guys going to mention in this thread what the archetypes are that you evaluated? I love the names but I have no idea what is going on in that table :stuck_out_tongue:

Thanks! A criteria for creating a strategy/archetype is a good name.

I do not intend to list out what those strategies are because I do not want to skew how other teams might select their own strategies and/or archetypes. We just want other teams to see that weighted decision matrices exist and that other teams use them.

Edit: just in case anyone wanted to make their own, this is the simple math that goes into computing a value quantity from a weighted decision matrix. (Pro tip: while a cell is highlighted in an Excel or a Sheets equation, hit “F4” to automatically insert $ in the column and row values to make that cell address absolute instead of relative.)

Yeah I think it’s a great resource for teams on seeing weighted objective tables done with this game! Not revealing the names now makes sense. Though if you don’t mind, I definitely would like to ask you guys later in the season to see if some of my guesses for some of those weird names are right.

Absolutely!

CAD of the chassis is complete!

It is the next evolution of our sheet metal chassis.

Critical information:
Flat 6WD
4x1.5in Colson Wheels
7/17ft/s Ball Shifters
6X Mini CIM
#35 Chain Drive

We’ve decided that a bellypan mounted to the top of your chassis is called a brainpan. Yours looks like a fine example!

Bahaha. Love it. I think we’ll use that term in lieu of ‘deck.’

Looks good. I assumes this means no drop center? Have you guys played around with that at all? From experience 3467 ran into issues with this after our chassis was machined.

Thanks! You are correct, no drop. We used a flat 6wd last year and absolutely loved it, even geared for 17ft/s single-speed with 6 CIMs. We used Colson wheels, which have a nice rounded edges. I imagine using a flat 6WD with a wheel that has a sharp corner or flange, like a plaction or hi-grip, the edge might dig in and make turning awful.

Credit where it is due: 125 used a flat 6WD in 2014, which gave us confidence to try it, and the FRC Design Calculator Rev 0 was used to calculate turning FoS ahead of testing to make sure that we were not asking for the impossible.

Nice that it worked for you guys. We drew inspiration from the same place that year (125 in 2014), but ended up shaving down our outer Colsons 1/16th.

At least that was an easy fix!

It’s also worth noting that we were well under-weight: 95lbs before bumpers and battery. <120lbs with.

This is the biggest advantage to using Colsons IMO. “Drop tuning” as we like to call it. Amount of needed drop can vary wildly based on wheelbase foot print & CG, so having the ability to do that quickly after the robot is all together is a huge benefit.

-Brando

We’re expecting chassis parts to be complete by this Tuesday, much earlier than anticipated.

Prototyping of power cube intakes has yielded interesting results, and we’re going to pursue a design that we haven’t seen in any of the Ri3D robots. But more on that later.

Our general power cube related CAD is progressing, taking heavy influence from 254 in 2011, our own 2015 robot Lovelace, and 1519 in 2016.