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Your guide to installing Smoothieboard in a Blue Box Laser Cutting machine
( See also blue-box-guide )
« Blue Box » laser cutters ( sometimes also referred to as K40 ) are cheap Chinese machines basically designed for laser engraving of stamps.
The electronics and software that come with it are generally considered barely usable, and are at the very least very limited.
However, the machine itself, while cutting cost at all corners, and not being of the best quality, is a good option ( and the cheapest option possible ) for anybody looking at getting started with laser cutting.
These machines can be found for $700 or even sometimes less on eBay, and have become more and more popular as people have started replacing the internal electronics, first with Arduino-based boards, and now with Smoothieboard. This allows for easier use, more software options, and makes for an overall much better machine.
Their work area is roughly A4 size, and the laser power is about 40W.
This allows the machine to cut and engrave plywood, MDF, balsa, cardboard, paper, leather, cloth, and PMMA ( acrylic ), up to about 5mm thickness.
This is a step-by-step guide to connecting your board to the various components of the laser cutter, configuring everything, from the beginning to actually cutting material.
This guide is a [community](http://smoothieware.org/irc) effort, and this page is a Wiki. Please don't hesitate to [edit it](#_editpage) to fix mistakes and add information, any help is very welcome.
About this guide
This guide is specific to the « Blue box » model that is very commonly found, but the information it contains should be useful for most Chinese laser cutters.
Larger Chinese models have higher quality, and function on basically the same principle ( except they use external stepper motor drivers ).
There is a more general guide: the Laser Cutter Guide. You should read it before you read this guide, as it contains much information you need to be familiar with to do things properly.
This guide is based on Stephane BUISSON’s blue box build log.
Safety
Lasers will make you blind. In an instant. In the blink of an eye, quite literally.
[!DANGER] Never look into the beam or at any surface the beam might reflect off of. Never have the machine powered while the door is open.
You are responsible for your own safety.
Eyes cannot be replaced.
If the machine does not come with a switch on the door that turns the laser off when the door is open, this is stupid and dangerous. Please install that switch.
If you leave your machine alone even for a few minutes, this can happen to you:
They can burn your house, and they can burn your eyes, be careful.
Comments:
- Converted the callout to a markdown alert/callout.
- The image source was kept as is, assuming the path will be corrected during the website migration.
- The HTML div tags were kept for the centered text, as markdown does not support text alignment.
Warnings
Before you start wiring your machine’s elements to the board, there are several things you need to keep in mind and be careful about during all of the assembly.
Make sure you read this. Seriously. Not kidding. Do it. It’s important.
[!DANGER] Polarity
Note the inversion between the 5mm and 3.5mm connectors
Always make sure the polarity is correct when wiring in power inputs (coming from the Power Supply). Reversed polarity can damage or destroy all or part of your board. Polarity is indicated on the board itself by the + and - signs. Double check. On older versions of the board, markings are partially hidden by the connector, making it confusing. Rely on only the diagrams.
To check the polarity of your power source, attach your multimeter probes to the two wires of your power source respectively. If the voltmeter reading is positive it implies that the red probe is connected to the positive wire (+) and the black probe to the negative wire (-).
The main (labeled VBB) power input has a reverse polarity protection, however, it will not hold forever. As soon as you notice something is wrong, turn the power supply off and check again.
[!DANGER] Disconnecting
Never disconnect or connect stepper motors from the stepper motor drivers while the board is powered (i.e., when the Power Supply is turned on).
The drivers have very good protection against most possible problems and are very hard to destroy accidentally. But it is possible.
[!WARNING] Shorts
Be careful that nothing metallic ever touches the board while it is powered on. Falling screwdrivers, nuts and bolts can cause shorts and destroy the board. Check the board before powering it on. Do not press the reset button with anything metallic, as you could slip and cause a short, use a plastic screwdriver or the like.
[!WARNING] Use the right connector
Always check the schematic before connecting power sources (coming from the Power Supply) to the board. Connected to the wrong connector can destroy components. A common example of this problem is plugging a power input cable, into the connector for an output, or plugging the limit switches in backwards.
[!WARNING] Crimping
Make absolutely sure of your connections using crimps or screw terminals, from wires to any type of connector, are very careful and well done. Connections (to the stepper motors for example) lost while the machine is running can destroy your board.
[!DANGER] Markings
In the case of the VBB power input, be careful. If your board came with connectors pre-soldered, the 5mm connector is present, and the polarity of that connector is that of the large traces in the wiring diagram to the right (red is +, blue is -). On some boards, the marking on the boards may be hidden by the connector itself, so for VBB, do not rely on the markings on the board, but on the diagrams on this page. However, if you did not get your connectors soldered, and want to solder a 3.5mm connector instead of a 5mm connector, also note that the polarity is the opposite.
[!INFO] USB v Ethernet
USB can, in some setups, be subject to interference, which causes disconnections, and can ruin your work. This is very hard to prevent if it happens even in normal conditions. Ethernet, on the other hand, does not have this problem: save yourself the trouble, and use Ethernet right away. It’s very nice. See Network for information on how to set it up.
[!WARNING] Destroying your board
If you receive a bad board, you will get a replacement. But if you destroy your own board, your only options will be to fix it yourself (which can be quite difficult), or get a new one.
This is why it is very important you make sure you do not destroy your own board. Smoothieboard is reasonably protected, but there are still things that will destroy it. The general idea is: if a part of the board gets too much power, it will get destroyed. Here are some common mistake users do that cause the board to get too much power and die:
- Plugging 12-24v (motor power) into anything you are not supposed to. Like the 5V line, or an end-stop or thermistor input for example. Problems with the 5V or 3.3V power are not as much of a problem as the board is 5V-tolerant, so wrong connections and shorts should be okay as long as they do not last too long.
- Shorting 12-24v to anything else, which is essentially the same as plugging it into a place you are not supposed to (see above). This can happen by dropping a metal object onto the board, bad soldering, loose wires, un-protected wires, etc …
- Using an inductive load (like a motor, fan or solenoid) on a MOSFET, without a diode across (see Fan documentation).
The general idea here is: always make sure everything is clean, and double-check everything before turning the power on. You can not learn by making mistakes here, as mistakes will likely cost you your board.
Electrostatic discharge can also destroy your board : make sure you properly ground everything.
[!DANGER] Heater safety
If your machine contains any heating element and uses the temperature control module to control it, please make sure you read the section about implementing all safety measures here, and implement as many as you can. Fires will kill you if you don’t.
[!DANGER] Grounding
Make sure your machine’s case and electronics are properly grounded, also make sure your location’s electrical installation’s grounding is correctly done.
See for example:
[!WARNING] Environmental hazards
Be aware of your environment: it’s not just the machine itself.
- On a laser cutter, the machine vents large quantities of toxic smoke and gas, make sure it is very well evacuated to a place where no-one is breathing them
- On a CNC-mill, dusts, like wood dust for example, can be explosive if they come in contact with a flame, be careful and take measures to limit dust in the air
- On a 3D printer, the acetone used to clean things is very flammable, and the sprays used to increase bed adherence are explosive, store them adequately and be careful when using them
In particular, you are even more in danger if you are using your machine in a confined space, always be on the watch for safety issues.
For a good read about safety, you can refer to the RepRap Wiki documentation on the subject
To properly understand some of the safety instructions in this documentation, basic knowledge about electricity is required. See this page for a refresher on the basics.
Inside the machine
If you look into your machine, you will see two main electronics items:
Basic power
First things first, you need to provide power to your Smoothieboard.
There is a 4-pin 5mm connector on your Smoothieboard with a VBB/GND and 5V labels.
You will want to connect 24V power to the VBB input on the Smoothieboard, 5V power to the 5V input on the Smoothieboard, and ground to GND:
Once this is wired, if you power the laser PSU, the Smoothieboard should turn on, and both the red VBB LED, and the orange 3.3V LED should light up.
Controlling the stepper motors
Once you have located each set of 4 wires, separate them from the rest, and for each, make a 4-pin connector using the connectors and crimps that came with the Smoothieboard.
Note: The stepper motor wires come on ribbon cables, and are arranged in a specific order. You need to keep that order when connecting them to the Smoothieboard, you cannot connect them in a random order. If you lost the order, look at the laser cutter guide, it has detailed information on how to figure this out.
Then connect the X stepper motor to the M1 stepper motor driver, and the Y stepper motor to the M2 stepper motor driver.
Finally, in your configuration file, change alpha_current and beta_current to the value 1 ( for 1 Ampere ), and change the alpha_steps_per_mm and beta_steps_per_mm to the value 157.575.
Once this is done, connect to the board via USB using software such as Pronterface or the web interface, power up the machine, and you should be able to move the stepper motors, and therefore the axes, using the controls in the software.