Lasersaur

Written by Suhayb Zeqlam

The Lasersaur

Introduction

To start, for the full experience please visit the OSF site. There you will find an easier reading experience, as well as files for configs and documentation. The Lasersaur is a CnC open source laser cutter. This is NOT a guide to built the Lasersaur, this is to transfer information from the current group to future groups. The main goal of the Lasersaur project is for students and faculty to have access to a laser CNC on campus for them to use for various projects. Most of the Lasersaur at this point has been built following this guide. One thing to make note of is that previous members did not build this but was built by a start up that the Open Source Hardware Enterprise purchased. Now, most of the machine is built close to what is specified by the guide but some parts are different and custom, some of these will be discussed later.

Goals

Our goals for the semester were described by our project specifications that the Lasersaur team defined at the start of the semester and can be seen below.

Our team were able to complete all the functional requirement goals. For value-added goals, the team started looking at costs for replacing the side panels that were more damaged and smaller with bigger cleaner ones. The Lasersaur can now be interfaced using a laptop that makes it easy for users to use.

Specifications

The laser that the machine uses is a C02 laser, documentation can be found in files. The main brain of the computer is the smoothieboard V1. There is a wiki page for the smoothieboard online and is probably the greatest resource for this specific Lasersaur. This wiki page contains everything from actually wiring the laser and saftey switches to gcode and configs to change in order to make sure this are running properly. When starting I recommend strongly reviewing this site and understand the insides and outs before continuing. That being said you will find majority of what you need here. Of course, just like the lasersaur guide, not everything matches to a T so pay attention to the details.

What did ours look like

As the semester ends, the Lasersaur has a lot of work to do but had a large focus on safety. An emergency stop was installed onto the front, limit switches and trying to close gaps where stray lasers could escape from. We were able to make interface with the entire system using laserGRBL. LaserGRBL has configuration setting built for smoothieboard, although it is still a work in progress and not perfect. The laser was not fully functioning for us but was receiving a PWM signal from the board. It was never tested but may work with LaserGRBL. Reasons it may not have been working is the laser is “expired” and has leaked out too much C02 or the wiring is wrong. The mirrors reflecting the beam are scratched but should only affect how focused the beam gets. WARNING WHEN TESTING THE LASER MAKE SURE NOBODY IS IN THE ROOM AND PEOPLE WHO ARE HAVE PROPER EYE PROTECTION YOU WILL LOSE YOUR VISION WARNING. Pictures for how we have the Lasersaur can be seen below and should be reasonably labeled. The config file can found with other files in the OSF.

What is there laying around

Since the Lasersaur is quite prehistoric there is quite a bit of stuff laying around. If you look under the Lasersaur, you will see right away that there is a good amount of materials that can serve as replacement to the chassis. In the drawers and cabinets there is a some test cuts, connectors, and other spare parts such as a motor and replacement mirror. There is two pairs of glasses that are properly rated for the laser, except one of them has a cracked frame (might be repairable with the 3D pen but not sure if thats a great idea). There is also a 3d printed chassis with an LED inside that fits perfectly on the end of the tube for the laser and helps adjust the mirrors to focus the beam without turning the laser on. It should be noted that the wires are broken on the led, but should be easy to replace. There is also a space mirror sitting around for reflecting said beam, those mirrors can easy cost anywhere between 200-300 dollars and we are unsure about the complete specs for the mirror. There is cheaper versions that can be found on Amazon although we are unsure if they are the exact ones.

picture of the reflective mirror

What’s left to work on

This is not a said and done list of what should be done before the Lasersaur is complete. This is an open source project and changes can be added till the enterprise deems it complete. The Lasersaur should be completely sealed off so no stray beams from the laser can escape the build of the machine. Next, the system should be safe of any possible failures. Safety switches should be working effectively, the cooling system works properly, and there is proper ventilation in the main chamber. The machine should be well secured and have parts that move around that should not be. The Lasersaur should be ready to cut but there is still some unknown issues with the laser.

Control

In order to communicate with the lasersaur there is two ways to go about it. You can use the arduino method, which is very primitive and should only be used to send Gcode to test the lasersaur. Any “higher level” actions such as homing, actual cutting and so on should be done in the LaserGRBL. Either way the baud rate that is being used 115200.

Arduino

As mentioned, the Arduino method of communicating with the Lasersaur is extremley primitive and should only be used to test gcode and test basic functions, such as movement, in the Lasersaur. In order to communicate with the lasersaur, connect to the smoothieboard with a laptop and select the proper com port, from there enter the serial port in the Arduino IDE and you should be ready to send code. If Arduino sends OK back after sending code your connection is good, otherwise check your baud rate, com port, and power to the Lasersaur.

LaserGRBL

Now, there should almost be no reason why Arduino is used to communicate. The Lasersaur has been set up to automatically work with LaserGRBL. Similar to Arduino, you connect to the smoothieboard with a laptop, choose the proper com port, and hit the connect button instead. BEFORE CLICKING CONNECT make sure LaserGRBL is set up to work with smoothieware, as guided by the LaserGRBL site. Once LaserGRBL is connected it should look like the image below.

Screenshot of LaserGRBL

From here, is it possible to send Gcode, home the device, test the laser, and move the axis. The yellow box on the right will show you the location of where the focus point is located compared to the 0,0 homing point. Although, the focus point might end up leaving the scope of the box, which the sizing can be fixed in the settings, under “Smoothie”. The arrows in the bottom left are for movement, where you can change steps and speed as well. The home button in the bottom left will take you to home while the button with the house and magnifying glass will home the nozzle. LaserGRBL will also show you progress of your cut in the top left, status in the bottom right and what Gcode has been executed can bet seen on the left. When searching for a way to communicate with the Lasersaur this was found to be the most effective method.

Laser information

To make abundantly clear, documentation for the laser and the power supply can be found in the files section. Again, the smoothieboard website also has it’s on documentation on properly wiring the power supply to the laser and board. The wiring as of now should theoretically work but when tested nothing happened.

A few things to make note of, the there is a PWM signal that goes from the smoothieboard to the power supply that has been assigned to P1.23, as defined by the config file. Now, the power specifies that it needs 220v input as well as the PWM is required to be ±5V. The smoothieboard should be outputting that but 5V, but as previous test cuts prove those should not be a big issue.

When controlling the laser, you can use GCode or LaserGRBL. How to control the lasersaur using laserGRBL can be found other the “Control” page. Underneath is some Gcode commands that can be found helpful for testing the laser. In the config file, the lasers maximum power is set to be 80%.

G-code to help test the laser

Speaking to some optics professionals who work at Michigan Tech, we have compiled a short list of reasons why the laser is not firing. This list, in no particular order, includes and is not limited to:

  • List item The tube has slowly been leaking over the years
  • List item The PWM signal may need to have a DC offset to keep the laser excited.
  • List item the mirrors and lens are too scratched up or not positioned properly to focus the beam.
  • List item Wiring issues between the power supply and smoothieboard.

Some of these issues might not be as serious, such as the PWM signal which could be handeled by the power supply but not easily tested due to having a very high voltage. The mirrors might be out of focus and can easily be refocused using the laser diode, but the scratches should not have any effect on how the laser cuts.

Dr. Oberloier (Shane), said that in the Spring semester of 2023 will be doing some quick testing to see if the problem is code or electrical related. I will be there helping them and if any new findings are found it will be reported in this document.

Wiring

Below you will be able to find pictures of how things were wired. Things that are confirmed to work are the motors that control the axis, the limit switches, emergency stop, and power to the Laser. It is unconfirmed if the laser can actually fire but the wiring, in theory, should work. Most of the wires should be labeled and easy followed.

In terms of improvements, wires should be rewired to avoid touching anything related to the laser as the temperature of the tube can reach high temperatures. Wires should also be managed properly so that they are out of the way of the focus point and cannot be done. We currently have a temporary solution but 3d printed clips that follow the beams of the chassis are a great solution. Currently the emergency stop is wired to turn off the laser power. In order to improve safety, the e-stop could be used to control the entire systems power and an improved 3d print for the lid limit switch holder to control laser power. A way of wiring the limit switch to the lid can be found in the smoothieboard guide and should be safe for the user and power supply.

One thing to point out is that all the pins can be found can be found on the smoothieboard website along side how the configs file can affect it.

One thing to note is that no pictures for the wiring for the motors and limit switches; the wiring on those are fine and should note need any work if using the LaserGRBL program. To note, if there is an issue with the “maximum” limit switches use the M119 code and investigate the config file to see if they are set for proper conditions.

The Universal Dc supplies are used to power the motors as well as the board and laser power supply. The one on the left sits at 5 volts and the one on the right is 25 volts.

Pictures:

Wiring for smoothieboard, DC power supplies, as well as the relay.
Picture of the other half of the back.
Wiring for the laser power supply.
Drawing of the e-stop to turn off the power to the laser power supply. I apologize for the image being vertical.

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