How to wire your smoothieboard
The main goals of this guide is to provide basic electrical knowledge to beginners and to share some usefull tips and ideas of how to achieve a nice wiring for your machines.
There’s thousands of awesome builders around the world with top notch parts and genius concepts but when it come to wire it often comes down to hide everything behind some panels and place two zip ties. While it will surely work, spending a few hours organizing and optimizing your wiring is a win-win. Your machine will be safer, cleaner and even you won’t need to hide everything anymore ;). It can save you time later debugging problems or upgrading parts without rewiring them all the way.
Table of Contents
This section is a basic summary of electricity. It will teach you how to safely wire your machine.
Basic electricity is not a really difficult domain. It’s dangerous if you don’t know what you’re doing and where is the danger. Remember that common sense is a great asset for not dying in the process.
First thing to mention is the fact that there is different electrical laws on different countries. They can be very (too) strict to irrelevant (dangerous), different units or different colors. This guide try to be as global as possible but it can’t be granted that everything apply in your country. If you have any doubts, please refer to your local rules.
Mains electricity is the general-purpose alternating-current (AC) electric power supply of your house. The nominal voltage is 110V (Volts) for North America, Japan and a few countries or 230V for most of the rest of the world. Most of our machines runs on single phase power. They should plug into a 3 poles electrical inlet composed of the following:
L is for live, also known as hot or phase. It carries the alternate current to your house. This is the main source of danger ! You should NEVER work on it while plugged. You shouldn't be able to touch exposed parts connected to L while plugged.
N is for neutral. It completes the electrical circuit remaining at a voltage in proximity to 0V. The neutral is connected to the ground (Earth), and therefore has nearly the same electrical potential as the earth. This prevents the power circuits from increasing beyond earth voltage, such as when they are struck by lightning or become otherwise charged.
Earth wire or ground (written GND, P or PE) connects the chassis of equipment to earth ground as a protection against faults (electric shock).
DC power are provided by power supply unit (PSU). Power supplies have input for the mains (L, N and PE) and a few outputs of DC voltage of a fixed value. Our machines usually use 12V or 24V PSU. %V PSU are often found for electronics. Co2 lasers have they own specific power supply.
DC power is at these voltages is not dangerous. You'll start to feel a small bite at 24V. By the way you should always work on your electrical components without power because the tiny circuit running on 3.3V isn't going to like to be touched by mistake by a 24V wire.
Earth them all !
As seen earlier, earth is for security. In case of default, by example from an equipement, a wire breaking or a screw coming loose, conductive parts of your machine may end connected to live ! And there's no way to detect it until you (or your kids, or your pets) touch it. As we do not like surprise BBQ, there's a simple way to prevent that; earthing everything.
Here's some examples of things to earth:
- your aluminium extrusion chassis
- your 230V heated bed support
- The metalsheet enclosure of your laser
Furthermore earthing those big conductive parts will helps with static electrical discharges and prevent them to damage your brand new smoothieboard !
TODO: How to connect earth, locking washer…
Your house has protection. They are different accordingly to your local rules. In case of electrical default they may be too slow to react so adding a fuse on the mains of your machine is a good idea. You can buy nice inlets with integrated fuse like this one:
TODO: how to
Need help ;)
How to choose your wires
Let's start our tour in cables jungle. Here's some basic tips about how to choose them. Some simple but nonetheless important notions because cables can overheat and potentially catch fire if they are sized improperly or wear out due to improper strain relief.
Thomas Sandalerer has made a great work resuming this chapter in this video:
Not much choice here, you got to choose between solid-core and stranded wire. Both have their pros/cons:
Solid-core or single-stranded are cheaper to make, stay in shape when bent and can be used in screw terminals without using ferrules. However they will break quickly if used on moving parts as stretching and compressing cooper too many times will break it.
Stranded wire are a bit more pricey but they are flexible and therefor suitable for movements. As they don't keep their shape you'll need a little more cable management to keep everything tidy. It's also a good idea to use ferrules on them when using screw terminals to keep all the tiny wires together.
Just make sure there are actually copper, as the cheaper copper-clad-aluminum wires will break way more easily under stress and fail over time in most connectors.
Another good alternative is silicone wire, as used in electric RC cars, it’s a good bit more expensive, but is actually a perfect match for the job.
Now that you know which type to use, we need to choose a wire size:
Wire's size (cross-section) determines how much current you can safely pass through. An under-sized wired will generate heat and isolation can melt leading to short circuit or catch fire. When I doubt, one rule: Bigger is safer !
There is different ways to speak of wire's sizes. The two mains are AWG (for American Wire Gauge) and mm2 (metric system). AWG's notation is followed by a number. Don't get confuse, a greater number indicate a smaller wire diameter and and a small number a bigger wire. You can find conversion charts between the two units online but what interest us more is how much amps each size can carry:
|mm2||Recommended amps||Maximum amps|
|0.5||0.5 A||1.5 A|
|0.75||2.5 A||5.0 A|
|1.0||3.0 A||10.0 A|
|1.5||6.0 A||15.0 A|
|2.5||15 A||25 A|
|4.0||20 A||40 A|
|6.0||25 A||60 A|
|10.0||40 A||100 A|
As a conclusion and using Thomas's video tiers:
Tier 1 - sensors, indicators, thermistors, small stepper (less than 1.5A like NEMA17) endstops, computer fans
can be wired in AWG20 or 0.5mm2
Tier 2 - Hotend Heaters, bigger motor (more than 1.5A like NEMA23), Mains of power supply, 230VAC heat pads
AWG12-18 or 1.5-2.5mm2
Tier 3 - low voltage heat pads (12-24VDC) or any amps-hungry element
AWG10 and more or 2.5mm2 and more
Color coding your wire is an easy way to identify them later by just looking at them. Color coding is generally ruled by electrical laws of countries. Here’s the most importants:
Brown, black or grey for Live
Light blue or white (US) for Neutral
Yellow-green for Earth
While our machines usually run at 12-24VDC, it’s a good idea to reserve at least the neutral and earth colors. Use at least a color for + and GND of your DC power
Example of common colors used in Switzerland:
N Light Blue
Lower AC XV Red/Orange
Lower AC 0V White/Green
Analog/digital data lines White/purple/blue/red
More informations: http://www.electronicshub.org/electrical-wiring-color-codes/
In this chapter you will find usefull components used in electrical cabinet to achieve nice and clean machines.The idea is to show you what exists on the market how it's called so you can source it.
You will be able to find this items either online on shops like aliexpress, bang good, ebay ect. or locally from electrician or best cabinets builders (right term?). Again take this as an insight of how we do thing in industrial electrical engineering.
Here's a few things you can use to manage your wires and cables but also pneumatic or water hoses, filament tubes, etc.
Also called cable ways, cable ducts. The slotted ones are very handy, wires can go in or out where you want. If you have a hot spot full of cables, you can cut somes parts to widthen the slot. Just cut to length and screw in place. They exist in many size of width and height, take some time to choose the right one. 20x20mm fits nicely on 2020 aluminium extrusion. Make sure to use if possible flat head screws or at least with no sharp edges who can damage your wires. The main downside is that you sometimes need to sacrifice space to place them, especially inside electrical cabinets or let's say the electronics area of your printer.
Mesh sleeves & Spiral wrap
Usefull to link moving parts over short distance like extruder carriages. They are no brain to use but once in place it's not the happiest thing to have to add new wires inside.
The holy grail for CNC routers but they fit perfectly on smaller 3d printers too. Like wire trunking they're available in many size by meter(s). Don't worry if the length is too long for your need. You can just remove some elements until you get the correct length. You will found two types, one closed, the other can be open all the way (to make you happier when adding new wires).
Terminals & connectors
You probably know well terminals as elements on your control board where you connect your wires. I'd like to introduce another type of terminals used in industry to simplify wiring job. They have similar function as screw terminals strips: connect circuits together. Where screw terminals have only 2 connection points these industrial terminals can have up to 4 connections points and can be are multilevel to save space. They exist in different size for different wire size. Standard size is up to 2.5mm2 (awg13) but your can find smaller ones capped for 0.5 or 0.75mm2 (awg18 or 20), again to save space.
Connection points can either be spring clamps or screws. Screw tend to be the "old" way while clamp is easier, faster and less prone to wire break (screw over tightened). Screw connections require crimping ferrules on flex wires.
On the left: 2 level terminal with 3 clamp connection points on each.
Each terminal or terminal's stage can be bridged with its neighbours (in red on the right). Bridges can be purchased at any special length from 2 to 10 or 20. The longer is the better since you can cut them afterward.
For example, make 2 groups of bridged terminals and use each to distribute power supply + and - easily from a single place and spare you the aweful spaghetti-thing going from a component to another to another to …
You can do that for every different voltage running on your machine.
Precision cutter plier
Soldering iron & solder
Screwdrivers 1 to 00
Lighter (poor's heat gun)
Zip tie gun
Crimping tools depending connectors used