Your guide to installing Smoothieboard in a Red Box Laser Cutting machine

This is an in progress guide / log of my conversion of a 60W Liaocheng city Dongchangfu District Branch painted laser equipment Co.(LCJBDZ) CNC laser cutter to run a Smoothieboard. They're the red box lasers available for very little money on Amazon.

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« Red Box » laser cutters are cheap Chinese machines that perform surprisingly well for their price, they're popular in maker spaces with limited budgets.

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 for anybody looking at getting started with laser cutting or looking to upgrade from a bluebox-guide.

These machines can be found for $2300 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 500mm x 700mm, and the laser power is about 60W.
This allows the machine to cut and engrave plywood, MDF, balsa, cardboard, paper, leather, cloth and PMMA ( acrylic ), up to about 7mm thickness. They can also etch glass, heat-discolor titanium, and activate cermark spray for marking metals.

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 effort, and this page is a Wiki. Please don't hesitate to edit it to fix mistakes and add information, any help is very welcome.

About this guide

This guide is specific to the « Red box » model that is very commonly found, but the information it contains should be useful for most chinese laser cutters.

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 M@ Dunlap's red box build log… okay, let's call it what it is, this guide is my red box build log…

Safety

Lasers will make you blind. In an instant. In the blink of what used to be an eye, quite literally.

Never look into the beam or at any surface the beam might reflect off of

Never have the laser powered while the door is open, there's already a glowy red switch on the side for exactly this reason.

You are responsible for your own safety.

Eyes can not be replaced.

While this machine does come with a safety switch on the door, it also comes with a bypass switch that obviates the door switch and has a counter intuitive label that might lead people (not naming names here) to keep the switch in the unsafe bypass position thinking that it is in the safe non-bypass position. This is stupid and dangerous. Unplug the bypass switch unless you know you need to use it.

Also, the seams around the door aren't protected and there's a set of vent holes in the front of the door. Plug all of these, both to improve safety by preventing people from looking in and to improve exhaust air flow (by forcing it to come in from the bottom). Some soft window insulation and some aluminum tape (respectively) work beautifully for these tasks.

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.

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Polarity

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 :

For a good read about safety, you can refer to the RepRap Wiki documentation on the subject

Endstops

The red box laser uses Fotek PL-05N inductive endstops only at the rear-right corner of the laser bed. This is problematic because it means that if the machine skips steps it can slam mirror first into the frame of the machine without passing over an endstop. Given that additional endstops are readily available and $6 each as part of this build I'm going to be adding at least one endstop in addition to the two it shipped with.

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Important Note The PL-05N uses the black wire as a signal wire NOT as ground. Ground is blue… for reasons. Don't mess this up or you could (probably, although I haven't tested this) fry your smoothieboard.