This instructable is how I went about creating the pictured T-REX model using my MPCNC CNC Machine and a 3.5 Watt L-Cheapo Laser bought from Endurance Lasers originally. This really does show what can be done with a Laser Diode instead of having to go for the bulkier CO2 Laser setups.

Step 1: My Equipment

Hardware

Custom CNC (MPCNC with Ramps 1.4 running Marlin)
L-Cheapo 3.5 watt bought from Endurance Lasers
LASER PROTECTION EYEWEAR (Yes, this is essential, A Laser will blind you, do not use your laser without the appropriate eyewear)

Software

AutoCAD 2018
Estlcam V11
Repetier V2.05Host
Notepad++

Step 2: T-Rex Plans

The plans I used are available at www.makecnc.com, this is a good resource for
Hobby CNC users, please note I have no affiliation with this company, I came upon them after a google search.

The plans come in several formats, for me I used DXF so I could import them into AutoCAD.

Step 3: Modifying Plans

My first steps was to modify the plans for use with the
current wood stock I had available which was sheets of 3mm – 3.4mm Plywood at 300mm x 210mm.

In AutoCAD I drew a rectangle of 300mm x 210mm to represent the wood stock, I then placed all of the components into one of these rectangles, in my case I needed 4 rectangles.

Step 4: Estlcam Settings

These are the settings I use within Estlcam for Laser Cutting

Step 5: Estlcam Engraving Setup

In Estlcam I opened the DXF file saved from the Modify Plans stage and imported them on a scale of millimeters.

In Estlcam I used the Engraving Tool set on Centred with Automatic Object Detection and clicked on each object I wanted to create a cutting path for, please note I did not cut the rectangles, they are only used for reference.

I zeroed my CNC 10mm x 10mm from the corner of the work piece, each rectangle represents a single work piece so these are done individually, I could have done all 4 at the same time, but decided to do one piece at a time.

My tool path depth is set at 3.4mm and my Laser Depth per
Pass is set at 0.43, which will work out at 8 passes per object dropping my Z Axis height 0.43 mm each pass.

When I was happy with my Estlcam setup I then saved the CNC program and Estlcam converts everything into GCODE.

Step 6: Editing GCODE Within Notepad ++ (May Not Be Required)

This next step may or may not be needed, I am just new to Estlcam and if this option exists great, if not my way works. I cannot find out how to turn a laser on and off within Estlcam so I put the codes in manually by editing the GCODE within Notepad++

So for each engraving I insert my Laser Start and End Codes, for me using Marlin and Ramps 1.4 my Laser On is Code M106 S*** *** represents the power to the laser 0 = off, 255 = full power and Laser Off Code is M107. Please see image, these codes are placed at the start and beginning of each Engraving Pattern.

Lastly within Notepad++ I do a find and Replace on my movement speed and change this from F*** (F*** being whatever speed it’s set to in the GCODE) to F200. Again being new to Estlcam I may be missing this option as it was easier for me to manually do the Feed rate than trying to work it out.

When happy I save the GCODE

Step 7: Repetier Host and Cutting

Using Repetier V2.05 Host.

To be honest this is the easiest part, only requires 3 Steps. First I click on Connect to connect to my CNC Machine, then Load to Load the GCODE file we saved earlier, then Print to Start the Cutting.

Before cutting please check your laser focusing.

Some info about my laser focus.

For me I found my laser was focused best at 65mm from top of cutting surface, so I would manually adjust my Z height to take into account the thickness of the Work Piece, in this case 3.4mm so I adjust my Z Height to 61.6mm, then the GCODE moves the Z Height back up to 65mm during operation, with a Z height decrease of 0.43mm each pass I found the focus to work great.

The only real issues I had with the whole cutting process was any kind of warping of the wood, since the focus is so precise warping does have impact on the cutting process where I found sometimes not all cuts passed fully through the wood. This was easily fixed by using a small craft knife to cut the parts that were not 100% through the wood.

Step 8: Photos of the Cutting Process

Few things to note.

I combined 2 of my rectangle sheets into one to save on wood. This is easy to do during the modify stage of the plans for cutting.

This is my first real project using a Laser Cutter on my CNC machine and my first Instructable.

I have to say I wasn't expecting much from a 3.5 Watt Laser Diode, but the Laser Diode went way above any expectation I had, as for lasers the 3.5 watt L-Cheapo bought from Endurance is a very good product that any hobbiest or model maker would benefit from.

Links

Endurance Lasers www.endurancelasers.com

L-Cheapo Lasers www.robots-everywhere.com

MPCNC https://www.v1engineering.com/

Estlcam www.estlcam.com

Repetier Host https://www.repetier.com/

Notepad ++ https://notepad-plus-plus.org/