Cheap 40W Laser Engraver from China

Posted on 19/06/2015 by brassfly

I have wanted a laser engraver for quite some time but the price has always been prohibitive for me. Recently though, I found some engravers from china on Amazon for about $500.00 USD and free shipping. Plus, I contacted the vendor and found that the unit would ship from California. I read all the reviews and they all agreed that the machine is great. However, the downside of these machines was the software that is included. After carefully considering all the relevant information I decided to purchase one.

The machine arrived in two days and to my dismay the packaging was damaged. Upon unboxing the machine I discovered that the window was damaged. I contacted the vendor and they offered to give me $50.00 back and I keep the unit, or I could return it and they would send another. I told them that I would test the unit out and then, if there were no other issues, I would decide which option I would pursue. In the end, everything worked well and I decided to keep the unit and accept the partial refund. Below is a picture of the unit.

Using acrylic glue, I was able to mend the window well enough. It is not easy to see in this picture, but the crack is significant. The next hurtle was the Moshidraw software that came with the unit. It was an abomination! I spent weeks trying and countless hour researching on the web. But alas, it was hopeless. It seems that there are a multitude of versions out there and I could not find a solution that would work for me. I decided to remove the interface card, which only works with the Moshidraw software, and use an Arduino Uno with GRBL 9i to run the machine.

Luckily for me others had already done all the heavy lifting when it comes to reverse engineering the machine. I found the most helpful information at Adventure in DIY Engineering, http://3dprintzothar.blogspot.com/2014/08/40-watt-chinese-co2-laser-upgrade-with.html, though I did do a few things differently.

I started by removing the Moshi card from the machine and scavenging the connectors from that board. Below is a picture of the Moshi board.

If you look closely you can see where I removed the connectors from the left side of the board. The folks at Adventures in DIY Engineering (ADE) used an Arduino Mega with a Ramps 1.4 and a version of Marlin that has been modified for the laser engraver. I elected to use an Arduino Uno and my own homebrew stepper driver breakout board with A4988 drivers installed. Below is a picture of my setup.

So you can see in the picture above the Uno is on the far left, in the center is the driver board, and to the right is a proto board that provides a breakout for the power supply connetions. On the proto board is a 2n2222 transistor that serves and a buffer between the Uno I/O pin and the laser drive control.

One of the things that I did differently from the folks at ADE is that, instead of using the test fire button input turn on and off the laser, I chose to use the same laser control that the original Moshi board used. This has several advantages, first and foremost, I retain the test fire button which is useful for aligning the mirrors. Secondly, I retain the manual laser enable button, which is very useful because it allows me to run a g-code program with the laser disabled to verify it will not do something stupid with the laser on. Basically, the way that I modified my machine it retains all of the original funtionality of the front panel.

Below is a sample cut that I made with the machine after the modification. I am very pleased with the results thus far.

When I get some time I will work on drawing a schematic for my build and post it. I have many more modifications planned for the future, but for now I am just happy that i can finally do something productive with the machine!

As always, thank you for listening and I welcome all comments!

Edit 12/30/2015:

Above is a drawing of how I wired my laser engraver. I did not include the connections for the stepper motors as this information is available at the link listed above. This drawing represents the things that I did differently from the folks at Adventures in DIY Engineering. As mentioned before the stepper driver breakout board (shown with the black background) is one that I created myself and accepts A4988 driver modules. I used this instead of the RAMPS 1.4 board that the ADE folks used. It is a very simple board that I isolation routed on my mini cnc mill. I can provide the Eagle files if anyone really wants them.

Using the system the way that I have it setup comes with special challanges. For instance the software that I use to generate G-code is CAMBAM and it requires some manual editing after generating the code. This is because I have to change the Z commands to M codes to turn on and off the laser. I use the spindle speed command Sxxx to control the laser power. Although the S command is capable of a range from 0-30,000...in this application S1000 represents 100% laser power and increasing the spindle speed above 1000 has no additional benefit. S100 = 10%, S200 = 20% and so on up to S1000 (100%).

I use my machine for cuting out shapes and it works very well for that. I have not spent any time trying to etch raster graphics, so I dont know how well it will do for that. In any case I hope that this information will be helpful!

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Cheap 40W Laser Engraver from China

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