- Take the X Axis assembly and place it into the case. Attach it to the Y carriages with M5 screws.
- I thought about how to build the cutting bed for a long time. The first iteration used a metal grate bought at the local hardware store. This worked fine, but left burn marks where ever the laser cut through and hit the grill. Professional machines use aluminum honeycomb, so I went looking for that. I found a reasonable price on Amazon and picked up a 12x24x1in piece. When I got it, I was surprised that, although 1in thick, it was still a little bit flexible… I would have to support it on all sides…
A little bit of time later, I came up with the following:
- Four lengths of 1in aluminum angle iron.
- 2 x 22.9 in
- 2 x 18 in with a 45 deg cut off one end
- I 3D printed the corner pieces, used them as a guide for drilling the mounting holes into the aluminum, then tapped the aluminum. I then used (Don't be mad, its what I had) #4-40 x 0.25in screws to secure through the plastic and into the aluminum. You could just as well use M3 or M2.5 screws.
- The whole assembly slides into the case and secures in the front with M5 bolts. The back is left floating, resting on the rear 2020 V slot.
Secure the Assembly
This is not a long section, but it is important. Now would be a good time to secure the whole assembly in the case. I found sliding the assembly all of the way forward worked well. I then slide it as far left as I could, leaving about 1/4in clearance between the outer wall of the case and the X axis motor. Run the head around a bit by hand and evaluate that it makes since in that location. When I was happy I used self tapping screws to come up from below through the bottom of the case, into the 1/2in sheet of MDF. This is also why you will see me assembling the unit on saw horses, I anticipated the need to work from below.
- I reinstalled the lids and bolted the two halves together, using an existing hole in the middle of the two halves.
- Then, I used some of the left over aluminum sheet from the bed and taped it in place with Aluminum Tape over the now exposed holes in the lid.
- I was putting this off. The first thing you may notice in the images above is that there is no longer any room for the electronics inside of the case. Luckily, I had a salvaged case that worked perfectly for my needs. I'm sorry I don't have a source for this part, it literally was pulled from a trash bin. You can see it mounted to the right side of my machine immediately above.
- First, I made a new face plate for the case. This face plate had an Amp meter, a Main Power and a Laser Power Switch. I cut this from sheet plastic by hand. The switches were salvaged from the original unit. The AMP meter was purchased from here: "Uxcell a11052500ux0047 0-20mA Analog DC Current Panel Meter Ammeter 85C1-A"
- Then, in the upper right corner of the case I drilled a 1in hole into the Laser Tube area. This hole served to route the laser power wires. I also drilled a hole in the lower right corner to route the motor and end stop wires.
- I then secured the PSU (I removed the blue film from the PSU, so now it is silver) and the Arduino Uno with GRBL shield.
- I then wired it as follows (A big thank you to http://donsthings.blogspot.com who has done a lot of research on these units and from which I based much of my work)
- In the above it is worth pointing out again the PWM signal. Using GRBL 1.1 the PWM signal was present on the End Stop -Z pin, not the Spindle Direction or Spindle Enable. I should also not that I tied the Laser Fire pin straight to ground to reduce the number of connections and complexity. I have not had an issue with this setup, but use at your own risk. I keep the laser switch off until just before I run a program. I also always turn the laser switch off before opening the lid. A recommended upgrade would be to place in series another switch to detect if the lid is open. I have opted to delay that upgrade.
- The end stops and motors were then wired as the GRBL shield was marked.
- You will also need to install stepper motor drivers in the X and Y axis and tune them accordingly. I leave those details to other sources that have covered it much better than I will.
Software and Firmware
Coming from using MARLIN and other 3D printer firmware, configuring GRBL was a refreshing experience. Most configuration for Marlin requires you to edit the source files. GRBL doesn’t really require this step for most 3 axis setups. I downloaded GRBL 1.1 and scanned the config.h file. In the end I only made one change to the file before uploading it.
I modified the homing cycles since my machine only has an x and y axis:
// REQUIRED: First move Z to clear workspace
#define HOMING_CYCLE_0 (1<<Z_AXIS)
#define HOMING_CYCLE_1 ((1<<X_AXIS)|(1<<Y_AXIS))
#define HOMING_CYCLE_0 ((1<<X_AXIS)|(1<<Y_AXIS))
//#define HOMING_CYCLE_1 ((1<<X_AXIS)|(1<<Y_AXIS))
Honestly though, this step didn’t seem to make much of a difference.
I uploaded the firmware via the Arduino editor and the instruction on the GRBL wiki. Then, using the Arduino Serial Monitor, I entered the following settings.
|Step pulse, microseconds
|Step idle delay, milliseconds
|Step port invert, mask
|Direction port invert, mask
|Step enable invert, boolean
|Limit pins invert, boolean
|Probe pin invert, boolean
|Status report, mask
|Junction deviation, mm
|Arc tolerance, mm
|Report inches, boolean
|Soft limits, boolean
|Hard limits, boolean
|Homing cycle, boolean
|Homing dir invert, mask
|Homing feed, mm/min
|Homing seek, mm/min
|Homing debounce, milliseconds
|Homing pull-off, mm
|Max spindle speed, RPM
|Min spindle speed, RPM
|Laser mode, boolean
|X Max rate, mm/min
|Y Max rate, mm/min
|Z Max rate, mm/min
|X Acceleration, mm/sec^2
|Y Acceleration, mm/sec^2
|Z Acceleration, mm/sec^2
|X Max travel, mm
|Y Max travel, mm
|Z Max travel, mm
I entered each one by typing the Setting number “$0=” followed by the desired value. You can then verify that the values have been entered by typing “$$”, which lists all of the configuration values. For more details, head over to the GRBL wiki.
Bill of Materials
The following is as complete a Bill of Materials (BOM) as I can generate. My build was completed with mostly items I had on hand from other projects and I spent a total of $5 in new hardware. Please also note, most of my links are to amazon products. I do most of my shopping there, so most of the items are found through my order history, but I also, by you using the links, receive a small cut that helps me keep my site active. If you decide not to purchase through these links, please consider donating the cost of a coffee so I can keep this site active and growing.