FRC 95 2018 Build Thread


#5

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.


#6

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


#7

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.


#8

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:


#9

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.)


#10

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.


#11

Absolutely!


#12

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


#13

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


#14

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


#15

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.


#16

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.


#17

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.


#18

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.


#19

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


#20

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.


#21

The SUMPRODUCT function is an even simpler way of doing this math.


#22

Latest CAD screen shot. The tower is coming together, as is a 4-bar linkage to move our cube collector. Still outstanding is the cube collector geometry, which has been subject to pervasive prototyping; the spool assembly for the lift; and our solution to climbing, which has finally left the concept phase.


#23

How tall is your robot? It was brought to my attention by 3005 to watch for Center of Gravity on the Cable Protectors and the Ramp, and while the height limit is 55 inches, a SCALE with OWNERSHIP is only 48 inches of clearance.


#24

Great looking build. I noticed the Pneumatics on the underside of your robot. We were thinking the same. If those were for CLIMBING from direct contact with the PLATFORM, Q134 of the Q&A was explicit in the clarification for CLIMBING.