[Ri3D] Help BOOM DONE. order stuff

FIRST General Forum
1

Chief Delphi Community,
I am in the process of ordering stuff for the 72 hour build.

I have a ton of questions and I can use your help.

What should I make sure I have on hand?

Provide suggestions below.

I think I have a handle on the basics (Motors, chain, bolts, gearboxes, aluminum…)

Teach me something new, or remind me about something I may not remember.

I will start things off with two questions about wiring.

Wire: I use RED & BLACK for the power IN side of the Talon/Victor and WHITE & BLUE for the power OUT side. To simplify things, I use 12g for all high current applications (no worrying about the extra weight - it isn’t that much and it gets the job done).

How much 12g wire of each color should I have on hand to be sure I don’t run out?

Connectors: The EEs on the team are not FIRSTers. They don’t like Anderson Power Pole Connectors for motor applications. I am inclined to have them use Andersons anyway since they are a popular choice among FIRSTers.

Two questions? Should I use Anderson Power Poles or not? If so, how many terminals and how many Red, Black, White and Blue housings should I have on hand?

Please share.

Joe J.

2

As you are not focusing on the ease of changing a failed component but rather fabrication it may be easier to use connectors the EE’s are more familiar/happy with.

We use Anderson connectors and zipwire (also called zipcord or bonded wire) as our go to power solution. It lets us be consistent in crimping tool usage for students and coupled with a ratcheting crimper has significantly reduced our issues with bad contacts.

If you use Anderson connectors on every motor/controller set each set uses 4 connectors and 8 contacts.

3

We plan on 8 speed controllers and 4 relays for motors on the robot. We then adjust as necesary.

BTW, we do not use the Anderson connectors on the motors and controllers. Over the 13 years I think I can count on one hand the number of times I really would have benefitted from using them during a competition.

4

I would order some banebots wheels. They have proven to work well for shooting mechanisms, intake maechanisms and claw mechanisms. You should probably look into the grippyness (there’s probably a better term but I can’t think of it.) of each type of wheel. The green ones have been very useful for picking up things like frisbees and inner tubes.
Here’s the link: http://banebots.com/c/WHB-WS

5

What else are they suggesting? I’ve been meaning to take some time to look into connectors suited for our purposes that don’t rely on crimping and if they have any suggestions I’d love to hear them. So far I’ve been investigating using the bullet connectors that I use on my quadcopters.

Things you probably aren’t forgetting:

Sensors are useful to design in. But they are much nicer to just have on hand. Having a half dozen limit switches handy is great, maybe a banner sensor or two (the old yellow trip sensors) for detecting when you have a game piece.

Pneumatics, if available, make for great alternatives to more complicated mechanisms. Maybe half on hand a couple of 8" stroke 1" bore cylinders, if you can also grab a few 3/4" bore ones for grabbers and the like. You’ll also need the appropriate hardware for these (fittings, tubing, tape, tanks, compressor).

6

Polyurethane cord has proven to be useful for making lightweight mechanisms to transport game pieces within a robot.

Typically, 1/4" diameter works well for many applications. You form it into a loop by welding the two ends of a length of cord together, using a small open flame to melt the ends of the cord, then placing them together, aligned, for about a minute. A little tricky, and takes a few tries to get the technique down. Use 4-6 parallel loops of cord strung around/between two spinning PVC pipes, one (or both) driven by a motor to make a conveyor. Some teams use two parallel conveyors, with the game piece between the conveyors, to move the game piece quicker.

Some teams use the flat ribbon form of the polyurethane extrusion, about 1" wide, 1/8" thick.

Recommend getting the cord WITHOUT the polyester cord reinforcement. The unreinforced cord has a few percent of stretch available, which can be useful in making the loop go around the PVC pipes which make the ends of the conveyor.

7

We used Anderson connectors for everything in 2011 and 2012. Was never really useful, honestly. If you want to pull a wire without unscrewing anything I would just use spade connectors or something. I’ll let someone else guess wire length for you, but you could always buy a bit too much and donate your unused wire to a local team.

For mechanisms, Banebots wheels are the right combination of cheap and useful. I’d get some VersaPlanetary stuff on hand since it’s an easy way to run a gear reduction with adjustable ratio. I’m sure you’ve got a good handle on what mechanical and structural stuff is good for FRC. I’d focus on stuff that is both easy to get and that teams are likely to have on hand.

8

My team used the hollow core belt with the quick connects without fault in 2012. Works well and the belts can be taken apart without cutting them.
Either one will work though.

9

A bit on powerpoles and proper usage would be nice. They are tricky to use and get right, we had that issue with them last season. If used properly, they can be highly useful though.

10

Bolts, nuts, washers and rivets. We use 1/4x20 bolts for the most part but also keep #10 and #8 around. Get various lengths I 1/4" increments. Make sure you have nylocks and washers. We also use 3/16" rivets.

Also, all those pesky wago connectors you need for the control system

We also keep plenty of shaft collars, 3/8, 1/2" around. Velcro is also handy to have, we stock 1" wide Velcro. Machine key stock is on hand as we’ll, 8mm, 1/8"

11

This is a great thread to read for teams as well.

I would also suggest:
surgical tubing
perforated PVC/Lexan for potential belly pan
encoders
gyro/accelerometer
extra wheel tread (can be used for grip on intake mechanisms, grip, etc)
bumper materials (cloth, plywood, pool noodles, staple gun)
variety of bearings

12

Very much looking forward to seeing the recommendations out there on tried and true Power Pole alternatives suitable for FRC.

13

For the power IN side of things, you really shouldn’t need too much - you want the motor controllers close to the PDB anyways. Based on the past few robots we’ve built, 20ft would probably be enough for multiple seasons!

For the power OUT side of things, though, it’s highly design dependent. If you end up building a forklift/elevator, you could need 10-20ft just to get from one controller to one motor! I would probably plan for 100ft, with the knowledge that it’ll probably end up being more than you need.

Connectors: The EEs on the team are not FIRSTers. They don’t like Anderson Power Pole Connectors for motor applications. I am inclined to have them use Andersons anyway since they are a popular choice among FIRSTers.

Two questions? Should I use Anderson Power Poles or not? If so, how many terminals and how many Red, Black, White and Blue housings should I have on hand?

We love the Power Poles. While you may not unplug them a lot at competition, they do make wiring the robot a lot easier in some cases. We always put them between the electrical board and the actual robot. That way the board is completely removable quickly and easily - it helps avoid getting metal shavings on the board! We also put them between any components that are designed to be removable - for example, in Rebound Rumble our shooter was removable. Having it wired separately made testing a lot easier - we could run it into a battery (through an old drill modified to plug into a robot battery and provide variable output to a pair of Power Poles) to run the shooter manually for testing. Having the power poles also means we can easily disconnect mechanisms during testing. Depending on design, this can be a big advantage - you can stick your head into someplace knowing the mechanism next to your nose isn’t going to move, giving you a better view of a different mechanism that’s having problems.

If they have better connectors they would prefer to use, I’d say go for it! Just because the FIRST community has mostly settled on one particular connector type doesn’t mean it’s the best, and it doesn’t mean we won’t love to see other types that might be better. They can change our minds!

As for quantity/color… Get a variety of colors and use them to color code your wires based on applications. For example, all the wires going to your shooter could be blue, going to the floor picker could be green, going to the drive train could be red, going to the climber could be orange, etc. Remember, if you put them in place once between a motor and a motor controller, you’ll need 4 connectors (2 for each lead, one from the controller, one from the motor). So as a base guess, I would say 4x the number of motors you anticipate would be the minimum you would need.

14

Joe, I have been using PowerPoles on all robots since 2006. I really like being able to replace motors quickly, and to insert a motor test circuit easily – the latter has helped frequently when trying to diagnose problems by isolating the issue to either the powertrain or the control system.

However, it might be even easier to get the same benefits by using Lever Nuts (AM-2575 and similar). Their rating is 32A, compared with 45A for the PowerPoles; however, I am not sure the de-rating practices followed to arrive at those figures were the same. [Any help here, Big Al?]

Just thinking about failure modes, the Lever Nuts appear to have an advantage. Getting reliable crimps with Power Pole contacts is not nearly as straightforward as I would like it to be, although with practice many students learn to do it well.

15

Here is what I try to keep on hand.

1x1 Aluminum Square 1/16" Wall - Metal Distributor $15/21’
1x1 Aluminum L 1/8" Wall - Metal Distributor $12/16ft

1/2" Hex Shaft - VEXpro
1/2" Tube Axle Stock - VEXpro

PVC, Plywood, 2"x4"s, Hardboard for prototyping

1/16" Lexan - Plastic distributor about $55 for 4’x8’ sheet
.09 aluminum sheet metal, we get scraps from one of our sponsors

#35 chain, master links, & half links

Bolts, rivets, lock nuts, we use #10-24 and 3/16 rivets

Wire it works well and is cheap, we normally use better 10AWG for motors
12 AWG Monoprice 50’ $16.58](http://www.monoprice.com/Product?c_id=102&cp_id=10239&cs_id=1023901&p_id=2816&seq=1&format=2)
18 AWG Monoprice 100’ $10.36](http://www.monoprice.com/Product?c_id=102&cp_id=10239&cs_id=1023904&p_id=4045&seq=1&format=2)
6 AWG wire for battery connectors emergencyelectricpowersystems. 1’ $0.84 http://goo.gl/ylnhQ (We actually used 4AWG last year for our 6 CIM drive)

PWM cables and connectors to make custom length wires normally from Hansen Hobbies but other places as well.

We use Anderson on every motor, but on the speed controllers we switched to the spade tabs and connectors
Mouser #571-42117-2 & 571-45204472

Polycord like others have mentioned
Conveyor tread like rough top, McMaster sells several varieties, good for grippers and rollers as well.

Zip ties, velcro, dual lock, double sided tape, gaffers tape, masking tape

Various plastic (ABS, Lexan, delrin, nylon) tubes for rollers and spacers

That’s most of our normal stuff, there is always other things around like constant force springs, and sheets of plastic or metal from other projects.

16

Did you guys ever replace any throughout the season?? or did they hold up pretty well.

17

We prefer flat belt polycord because it’s much quicker, faster, and lighter to make rollers. What we did last year is we got 1.25" OD 1.125" ID aluminum tube, and just cutoff at whatever length we needed. Bearings just press in and you can make hubs if needed. No need to groove either. You just wrap electrical tape where you want the polycord and the belt walks back into place if it ever moves. Also, it allows for a smaller gearbox ratio which further saves weight.

18

We have been looking into this as well. How do you go about welding it? We haven’t had much success in our limited attempts.

No we didn’t, we did have a few come undone because we didn’t make the wires long enough or didn’t strain relief properly.

19

We ended up buying the expensive belt welder in 2012. Before that with circular belt we had made jigs. If you don’t want to invest into the belt welder that is probably your best bet.

20

Colored electrical tape or wire markers, to mark electrical components and wiring.