Wires and connectors
We recommend using 22AWG or 20AWG multi-strand wires throughout your system. 18AWG wires can be used for power, but they may be hard to make connectors with. Your mileage may vary.
The power and communications board will need to be directly connected to the power supply. You will need to wire power to each of your boards from your power and communications board.
The signal wires don't carry much current, so they can be smaller than the other wires. You can usually find these wires pretty easily. Cables such as ethernet and phone cords contain multiple pairs of wires that are perfect for carrying signal... that's what they do! Simply crimp/solder on connectors to these and you're ready to go. Try to avoid solid core wire, particularly for cables that may move as the RepRap operates. Go for the stuff with lots of little strands inside, called - logically - multi-strand wire.
High Temperature Wire
This is often suggested for wiring up thermistors and resistors for hot ends.
- other uses?
- suitable connectors and connecting methods?
Making Cables (Housed connectors)
Tools You'll Need
- wire strippers (nail clippers work great!)
- needle nose pliers (small ones)
- 22 AWG wire
- crimp-on terminal connectors
- soldering toolkit
In order to hook up all the various boards and devices for your RepRap machine, you will need to make cables. Generally this is accomplished by taking raw wires, stripping the ends, crimping a connector on, and then inserting that connector into the connector housing where it locks into place. This sounds easy, but can sometimes be quite frustrating. Here are some tips.
Hold the Wire / Crimp Assembly Properly
As simple as this sounds, it can make a huge difference. These things are small, easy to drop, and tough to align. The proper technique can make this much easier. Using your dominant hand, hold it palm up. Take the wire over your palm, along your index finger. With your free hand, grab a crimp-on terminal, and place it at the end of your index finger. Using your thumb, press down on the wire which should be properly placed on the terminal. Most crimp terminals have two sets of crimp tabs. One set is designed to crimp onto the insulation, the other is designed to crimp onto the wire itself. The proper placement is then to have the insulation be just a hair past the first set of tabs, with the wire extending all the way in. Then, with your free hand, crimp the connector on.
Properly Crimping the Wire
If you have access to a crimping tool, you're set. Otherwise, use a set of needle nose pliers. First, crimp the tabs that are for the insulation. Once that is secure, then crimp the wire tabs. Doing it in this order will make it easier, as the wire crimp is the more important one and the assembly will be much more stable after the first crimp. Be careful to only crimp the tabs sticking out, and not the base of the crimp, as it will bend it out of shape and make it hard (or impossible) to insert into the connection housing. If you do this properly, your crimp will be strong and you won't have to solder it.
Optional: Solder Your Crimp
This little hack isn't exactly orthodox. Electronics purists will probably have a heart attack hearing it. I find that even a very crappy crimp can be made into a solid connection that can handle some abuse, simply by applying a bit of solder to the connection. Basically what you want to do is heat up the crimp connector (that is already crimped to a wire.) Take care not to burn the insulation off the wire. Then, when its hot, apply a tiny bit of solder, just enough to wet the wires and the connector. Its best to do the soldering from the top of the crimp-on connector, as the solder will be able to flow to the wires better. Take care that the solder doesn't go anywhere else. If it wanders down towards the terminal, it can make it difficult to insert into the connector housing, or even interfere with inserting the connector.
Insert Cable into Housing
The connectors that are sourced in the bill of materials have two important properties:
- They are polarized (meaning they only connect in one orientation)
- They are friction lock (meaning that a connector will generally stay connected)
There are three holes for each pin on the connector housing. There is a big hole on the top. This is where you insert the wire and crimp terminal. The crimp terminal has a metal tab on the bottom that sticks out. As the crimp terminal slides down the hole, eventually the tab pops out of the second hole in the housing, which locks it in place. This prevents the wire from pulling out of the housing. Because of this, it is very important you double check which hole to insert the wire before inserting, as it can be rather difficult to remove a wire after it has been inserted. Finally, there is a small hole on the bottom of the connector where the metal posts on the header enter to make contact with the crimp terminals.
Making Cables (Non-housed connectors)
Slide on heat shrink and insulate
Most hardware stores, hobby shops, and electronics places sell wires, but they will often be pricey and/or marked up. YMMV.
Alternatively, a simple google search for the gauge + AWG will give you some good results. Remember to get at least 2-3 colours to help you keep track of positive/negative. You may find that 6-core "security cable" is a cheap way of buying lots of different colours of signal wire