Build season week 1

[GeeTwo]

I realized that it is not clear from my earlier post, but our week 1 prototyping was primarily for the purpose of determining the "difficulty" of various manipulator approaches. Of course, we always want to remember the key points were from these efforts!

As I read through the responses, I realize that someone should more clearly state that the design process should generally run:

1. Understand the rules (requirements)
2. Plan your strategy (that is: which requirements/rules/scoring opportunities take priority)
3. Prepare two or more designs
4. Evaluate designs against your strategy and priorities; pick a design.
5. As problems emerge, evaluate proposed design changes against your strategy and real-world findings

Most teams should probably be in step 3-5 overall at the end of the first week; we have been both significantly ahead of and significantly behind this in various years. We currently strive to be at step 5 for the drive system and step 3 or 4 for manipulators by the end of week 1.

[Alan Walker PE]

Originally Posted by GeeTwo

I realized that it is not clear from my earlier post, but our week 1 prototyping was primarily for the purpose of determining the "difficulty" of various manipulator approaches. Of course, we always want to remember the key points were from these efforts!

As I read through the responses, I realize that someone should more clearly state that the design process should generally run:

1. Understand the rules (requirements)
2. Plan your strategy (that is: which requirements/rules/scoring opportunities take priority)
3. Prepare two or more designs
4. Evaluate designs against your strategy and priorities; pick a design.
5. As problems emerge, evaluate proposed design changes against your strategy and real-world findings

Most teams should probably be in step 3-5 overall at the end of the first week; we have been both significantly ahead of and significantly behind this in various years. We currently strive to be at step 5 for the drive system and step 3 or 4 for manipulators by the end of week 1.

This is my fourth year in FRC as a mentor and my first post to Chief Delphi. My team started using bike chains last year. Why shouldn't we be using master links? Forgive me if I have not searched on "Master Links" before asking this question. I've never had much success with Chief Delphi. Earlier today, I learned at a local FRC workshop that for the best Chief Delphi results I should login, use the advanced search, and look at the date of the search results.

[GeeTwo]

Originally Posted by Alan Walker PE

This is my fourth year in FRC as a mentor and my first post to Chief Delphi. My team started using bike chains last year. Why shouldn't we be using master links?

The most recent thread to cover this ground is Chain vs Belts?

The bottom line on master links is that they are the weak point in a chain. Even when they are mechanically as strong, they are a bit wider or thicker, and are more likely to get struck or snagged on other items. Shock forces seem to occasionally disassemble them.

In lieu of master links, we now use a tool which can build the chain in a seamless loop.

For #25, the Dark Soul Chain Tool is the only one I've found. I recommend getting some extra pins; one of our students broke the extractor pin while learning to use it (most likely improper alignment).
For #35, we use this tool.
Similar tools are available for larger size chain, as well.

These tools can be used to assemble chain "in place" if the run is long enough and there is enough access space, or to assemble the loop on the bench (preferred when you can). The #35 tool shown includes a holder to help "in-place" assembly.

Note that the Dark Soul tool is sized for "regular duty" #25 chain. With a bit extra torque on removal of the first pin or two, you can expand it to work on "heavy duty" chain, but once you do, you will not be able to use it easily on regular duty again (it will be too easy to push pins completely clear of the far plate).

Edit: Responding to Cothron's comments below: There are teams which use #40 bicycle chain. (Example: 364, Team Fusion of Gulfport, MS). While #40 bicycle chain and plate sprockets are easier to source locally than #25 and #35 (at least here in Slidell), interfacing these sprockets to FRC wheels and gearbox shafts requires machining precision that is beyond many teams, and often not worth the extra time for those who do have the capabilities.

Edit2: Another thing we do early in the build, though usually week 2 or 3, is the "design presentation". In the early weeks, most of the build chains spend at least a few days waiting on parts to arrive. At the point when we think this is at a maximum, we stand down for an hour or more to recalibrate the team. As technical director, I prepare the top level brief describing key game rules, our game & design strategy, and our design,to the level it has been determined. For items still working with a couple of options, we brief everything still on the table. We encourage questions to be asked as they arise, rather than waiting for a "questions window", to reduce the chance that questions will be forgotten. While I organize, I get the sub-teams to present the briefs when they are comfortable doing so, and to answer all but the simplest questions. The main point is to bring the team's understanding of what we're doing together. To do this, they need good gouge*.

*Good gouge is a US Navy term for "information and/or advice straight from the real experts (that is, those with real world experience) which has not been 'normalized' into what leadership thinks it ought to be". In the interest of full disclosure, I was never IN the Navy, but have worked as a federal employee FOR the Navy for over 28 years. If an actual sailor wants to tweak or replace my definition of good gouge, please do so!

[MARS_James]

After we get everything settled at the kickoff we host, our break down usually goes like this:

1. Watch the kick off video again (Repeat about 3x)
1B. While watching we are printing out copies of the game manual
2. Begin going over the simple parts of the game (What Scores Points)
3. Establish the robot limitations (Height, Weight, Size)
4. Go over more important details of the game (How many game pieces can we hold, how many game pieces are on the field at 1 time, do game pieces circulate (2016) or once scored are they done (2013)
5. What is the ranking criteria (Average Score, QP, Win Loss)
6. Go over game play rules (Where are the safe zones, what areas are off limits, how long is autonomous)
7. Go over specific robot rules (Bumper rules, Extensions out side frame perimeter, expanding beyond starting size)

Once we have gone over that depending on time we either break for the first day or go into ranking what is important for the robot to do. For 2016 it went something like:
1. Move.
2. Manipulate boulders.
3. Cross 3 defenses that can be on the field at any time.
4. Score High Goals
5. Climb

After the first day usually I go back over the rules and create a power point to outline some of the specifics of the game (along with visuals) to help everyone understand the game better. We then either go back over the list of importance or we make it the first time depending on if it was made on Saturday. We then discuss what we think is the best drive train archetype to use (Tank, Mecanum, Swerve) and then begin prototyping drive trains as well as manipulators and scoring mechanisms (both CAD and real world prototypes are used) until about the middle of the week. We then meet discuss the competing ideas for the robot, vote on which way we are going to focus our efforts on, then prototype some more of the design we decided on.


That is usually our first week of build, the only thing that we have the advantage on is that we already have the team built field done to look at (Which we also have open to anyone who wants to come down through the entire build season). But once a decision is made we order parts ASAP and begin manufacturing what we need to.

[Cothron Theiss]

Originally Posted by Alan Walker PE

This is my fourth year in FRC as a mentor and my first post to Chief Delphi. My team started using bike chains last year. Why shouldn't we be using master links? Forgive me if I have not searched on "Master Links" before asking this question. I've never had much success with Chief Delphi. Earlier today, I learned at a local FRC workshop that for the best Chief Delphi results I should login, use the advanced search, and look at the date of the search results.

One trick of Chief Delphi is learning what search terms will yield the discussions you want to read about. Chief Delphi threads tend to wander off of their original topic, which is what I'm about to do.

When you say you started using bike chain, what pitch is the chain you're using? Modern bicycle chain is a narrow ANSI #40 pitch, or 1/2" pitch. The vast majority of applications for chain in FRC can be better solved with #25 or #35 chain, and the major suppliers for FRC stick with #25 and #35 sprockets and chain.

[Type]

During the first day of Build Season, we go over all the rules, and see the best way to score points. We don't meet on Sunday but we meet on Monday and finalize what we want our robot to do, and start figuring out what mechanisms that it will take to achieve this. So for example, we decided what type of drivetrain would be required to get over the moat, the rockwall, CDF, etc. We did that for every aspect of the game. We intended to be able to do everything but when we did the math and weight came down to a concern, we abandoned the idea of scaling and we later learned that we only have about 1 to 2" of ground clearance on our robot so ramparts and the rough terrain weren't an option.

[Eric Scheuing]

In the past couple years, we've shied away from doing any actual robot design for the first couple days. We typically take a day to digest the game, understand the rules, and determine how to play most effectively. This leads into discussion of robot design, usually starting with drivetrain and building up from there.