I am making a list of everything that we should buy for next year for the electrical team and I was wondering if you could share with me an example of your own for equipment list
Head of electronics
Get this terminal crimper for the battery cables:
You won’t believe how well this thing works for $29 (although I don’t know how much it will cost in Israel).
We tried the yellow hydraulic crimper you’ll see sold under various names.
avoid this one like the plague
After 10 terminals it will leak a most foul smelling oil everywhere.
We prefer to make our own PWM and sensor cables. The commercially available cables may have improved over the past few years, but we like having the flexibility to make exactly what we need. Here are the part numbers for what we use (all Molex numbers):
Female contacts: 16-02-1114
Male contacts: 16-02-0114
3-contact housings: 50-57-9003
4-contact housings: 50-57-9004
5-contact housings: 50-57-9005
Crimper: 64016-0201 (sorry, $130!)
Use good 22AWG wire with thin insulation and at least 19 strand count. The 7 strand wire used in many PWM cables breaks after a few flex cycles.
You can get other colors of Power pole connectors at Powerwerx. We used them for canbus, sensors, just about everything. And you can key connections in different directions so they literally cannot be plugged in to the wrong thing. Powerwerx also sells the crimper, and have 15A, 30A, and 45A crimps. Great for offseason projects and test beds too.
Wire. Flexible type (high strand count) in several sizes (10 to 18 at least)
Wire strippers. The ‘kinematic’ type (like these).
Contacts and housings (depends on connections you use. Recommend Anderson Powerpoles)
Screwdrivers (very small blade-type to mid-size philips)
Pliers (including needle-nose)
A soldering iron (25 W) and solder
Electrical tape of good quality (black)
Heat-shrink tubing assortment
Crimp-type insulated spade, ring and 1/4" terminals in various sizes, and a RATTCHETING crimper for them.
Wire ties: 1/8" x 4-5", 3/16" x 12", 1/4" x 12". Hundreds of them.
Some spiral-type wire covering
Marking tape: colored tape or label-maker tape to mark ALL wires at both ends.
That’s what i can think of at the moment
Do you guys use the PowerPoles on your competition robot too? We had a couple issues with them coming off the wires or disconnecting during tournament, though that could be due to user error.
We have used them almost exclusively for the past 4+ years, and occassionally before then. We found the biggest problem with the wires being pulled from the contacts came from either the wrong crimp tool being used, or being used improperly. Through training and some simple QC (pull and wiggle test) we don’t see many issues.
If the connection is one that is unplugged frequently we have seen that the “locking” of the two plastic housings degrades. To help mediate the risk we simply place a zip tie around the connection.
TL;DR - we are huge fans of the Powerpoles for competition robots, practice robots, R&D projects, and beyond.
They work great with the proper process. A few things to make sure of:
- Use the proper size wire in the proper size terminal
- Strip the wire the appropriate amount and make sure that your wire cut is pretty straight and you don’t have extra nicks in the cable. Too much exposed copper can lead to bends and breaks, nicks can lead to breaks, and not enough copper can lead to power connections
- Do a pull test after EVERY crimp. Though the Anderson crimper really works pretty well where if you squeeze it down to the point where it releases on it’s own you’re probably fine
- make sure the metal tab is fully inserted with the tab going over the metal tongue in the plastic housing. If it doesnt click or can be pulled out easily after inserting the crimp into the housing you’ve probably done something wrong.
- Perhaps most importantly, have a proper strain relief/bend radius on your wires. Ideally you wires should be zip tied to structure somewhere shortly after it’s connection so that any strain on the wire is taken by the zip tie - not the connector.
- I like to have a consistent way that the andersons are connected. Personally I’ve gone with “red on the right” by looking at the connectors from what I consider top down. (I consider the metal tongue to be the bottom of the connector). This way the connectors should be consistent across everything.
If you’re having problems with the andersons disconnecting - you can get the 2 pronged tab that holds them together.
Ha! I decided to standardize “Red On Right” for my team too! I drew a handy illustration on the shop chalkboard to declare it to all.
If you want to use your own sensors/cables (we used in-wall style four-conductor alarm wire for encoders) I’d reccomend investing in a “PWM” or Dupont connector set and crimper. We got a set like this.
Starting with the basics:
- really good side cutters/snips
- a set of small screwdrivers
- tiny needle nose pliers
- good wire strippers
- the appropriate crimpers for whatever terminals you use (whether they’re spade connectors, ring terminals, or andersons)
- electrical tape
- heat shrink of various sizes
- heat gun
Some of the “nice to haves” but border on “necessary” to me:
- Anderson connectors for everything. I like to get green and yellow ones for mouser for our imagery
- lots of 15, 30, 45 pins for the andersons
- More of the 15, 30, and 45 pins
- “helping hands” alligator clips
- ^^ preferably with a magnifying glass
- a flexible light stand
- an electronics work bench. We got one from Harbor Freight for ~ $70 https://www.amazon.com/HF-99681-Multipurpose-Workbench-Lighting/dp/B006HVFPK6/ref=sr_1_5?s=hi&ie=UTF8&qid=1466025725&sr=1-5&keywords=harbor+freight+workbench
- your cable management of choice - probably lots of tiny zip ties
- Make sure you have good side cutters that can cut close to the end of the zip tie connector so it’s smooth and people dont cut themselves
- I’d consider getting the crimper and ferrules from cross the road electronics for the VRM. We tried some from Amazon that I thought were right, but we seem to have weekend our VRM Weidmuller connectors, and they snapped a lot
Once you get that, and if money is available:
- a good soldering iron, IMO at least 40 W (I dislike soldering irons with set screws).
- various tips for the soldering iron (small conic, large conic, large flat…the right soldering iron tip is critical for translating heat!)
- Really make sure you know how the soldering process goes. Too many people think you solder by “painting” solder on. You have to hold the tip in place to transfer heat and you should know what a good solder join looks like. You also need to know where the “hot” part of the tip is…it’s often not at the end of the tip.
- solder iron tip cleaner (I like brass wire sponges)
- solder wick
I would also suggest looking into stocking some basic sensors ahead of time as well.
1/4 inch shaft encoders
If your team also covers the vision processing, whatever camera and boards you plan to use.
+1. Was so busy thinking about the tools for electrical I didn’t think to include sensors. limit switches are something easy for any FRC participants to add to make their robots more robust/controllable; potentiometers, gyros, and encoders really aren’t hard either nowadays with all the WPIlibs.