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Originally Posted by Zebra_Fact_Man
- Use the KOP frame. It's actually really good.
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Everything I've read here is spot on. Get local help. Keep it simple. Have a project plan. Finish far enough in advance of bag-and-tag to have some driver practice. Consider designs "not invented here". Keep everyone working on something useful. Build field elements. Go COTS (Commercial off-the-shelf) whenever you can afford it.
I'll go on a bit more detail on the chassis and materials and strategy about strategy:
We used the KOP chassis our rookie year and again this year. We opted out of the KOP chassis the other two, and in both cases we would have used the KOP as a starting point and modified in much less time and headache than we had. Remember is to think any changes to the chassis through before you pick up a saw or drill. Our rookie year was Rebound Rumble where you had to pick up nerf basketballs, and we cut open the front of the chassis to bring them into our feeder. We never did get the frame square again!
Watch the weight limit. That slotted extrusion is great for prototypes, but it just gets too heavy for competition. We use 1/8" aluminum stock for most of our framing and 10-32 bolts to hold it together, with steel angle braces from the hardware store at junctions which must stay square.
Use hex shafts for your gearboxes and other shafts if you can afford it - we've lost several matches and many hours due to missing or lost keys. Buy twice as many shaft collars as you think you'll need - at $4 a pop, you don't want to have to wait for it to be shipped to you at the last minute. Buy spares. High-end teams run their motors and parts hard, and need to have enough spare parts on hand to build two more robots, but most teams can only manage about a quarter of that, so we have to be more careful.
Do the math. Find someone who can read a motor performance curve and understands a gear ratio - two would be even better. Use the motor calculator and other resources on this forum. If you can't figure it out, or want someone to check your math, start another thread here - it's a rare question that doesn't get a useful response within a day, especially during build season. Story: Our rookie year, we built a device to push down on a field element (bridge) that was underpowered by about a factor of ten because no one calculated the weight of the bridge until we got to our regional and it didn't work. We also built a ball launcher that could throw a ball full-court, but never put one in a hoop because we reached WAY too far in finesse.
Don't use pneumatic pistons for something that needs to stop at various points along its travel. It's possible, but you could work weeks getting it right the first time. Don't use a motor to hold something in place; motors are designed to spend most of their time running fast at fairly low torque. Figure out how much current you'll draw with each motor and other device to make sure you won't trip that breaker, or the main at 120A. The standard compressor is designed for a 7% duty cycle - if you're running it much more than that, find another compressor with the same cfm rating, but a higher duty cycle. Assign a battery manager - without fresh batteries, robots brown out, causing computers and other parts to shut down.
READ THE RULES! After you have a design, read the rules again to make sure you're in compliance. Any time you come up with a strategy that you intend to use, check it against the rules.
If you're in a regional that isn't the first week, watch some video the first week or two. See what does and doesn't work, and you may decide to adjust strategy before your regional. You may also find out that some of the rules are being judged differently than you read them. For example, we read the rules last year (3.1.4 C)
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A BALL is considered SCORED in an ALLIANCE’S GOAL if
A. a ROBOT causes one (1) of their ALLIANCE’S BALLS to cross completely through the opening(s) of one (1) of
their ALLIANCE’S GOALS without intervening human contact,
B. the ALLIANCE ROBOT last in contact with the BALL was entirely between the TRUSS and their ALLIANCE’S
HIGH GOALS, and
C. the BALL is not in contact with any ROBOT from that ALLIANCE.
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to mean that pushing the ball into the goal at ground level did not count as the ball was in contact with the robot as it passed through the goal. It did count; I can only presume that A and C were intended to be sequential rather than simultaneous.