Small (but scalable) laser engraver/cutter

Introduction

I needed a laser cutter, but the space in my workshop is very limited and all commercially available cutters were too big for me. Therefore, I designed my own with a working area of 12 × 12 cm, using 250 mm and 200 mm ALU 4020 and 2020 profiles. The overall dimensions of my cutter are approximately 30 × 30 × 24 cm.

However, the design is fully scalable if you use longer profiles. I believe that the strength of the structure will be sufficient even when using profiles of double the length (then the working area will be around 35 × 35 cm).

I also developed my own small PCB for the electronics based on FluidNC software:

https://github.com/serych/Laser_Cutter_Electronics

Some parts are designed specifically for this electronics board and the power supply I used, so if you use a different type of electronics and/or power supply, you may not need to print them.

Parts needed

• ALU profiles

- 4020 – 250 mm – 2 pcs

- 4020 – 200 mm – 2 pcs

- 2020 – 250 mm – 1 pc

- Corner joints for ALU profiles – 10 pcs

- Screws and insertable bolts for ALU profiles – approximately 30 pcs

• Stepper motors and accessories

- Stepper motors 17HS2408 (or other similar NEMA 17) – 2 pcs

- Timing belt, 6 mm – 1 m for the small version (scale the length if you use longer profiles)

- Timing belt pulleys, 16T, width 6 mm, bore 5 mm – 3 pcs

- Flexible stepper motor shaft coupler, 5 mm – 1 pc

- Steel or aluminium shaft, diameter 5 mm, length 220 mm (scale the length if you use longer profiles)

- Ball bearing P625ZZ – 1 pc

- Creality printer POM wheels, diameter 24.2 mm – 12 pcs

• Other

- M2 × 15 mm screws and heat-set inserts for belt tensioners – 3 + 3 pcs

- M3 × 12 mm screws for NEMA motors – 8 pcs

- M5 × 40 mm screws for POM wheels – 12 pcs

- M4 × 8 mm screws for laser rail fastening – 2 pcs

- M3 × 10 mm screws for laser mount – 4 pcs

- Self-closing textile cable sleeves, diameter 5 mm and 10 mm – 1 + 1 m

(scale the length if you use longer profiles)

• Printed parts

• Laser

- Chinese laser of your choice, something like: "Laser Module 450nm 40W"

Assembly instructions

Start by mounting the main frame using the corner joints. Insert four insertable bolts into the bottom rail of the rear shorter profile, and two bolts into both the top and bottom rails of the front shorter profile. These bolts will later be used for mounting the feet, electronics, and power supply, but they must be inserted at this stage.

The shorter profiles should be placed between the longer ones so that the resulting frame is nearly square. Make sure the assembled frame forms a perfectly flat plane.

Mount the Y-axis motor on the `Motor_panel_R`, then assemble the wheels and one `Motor_panel_contra` onto one of the longer frame profiles. This step is a bit tricky, but doable. The assembled carriage should roll smoothly along the profile without any play. Then mount the belt pulley onto the motor shaft and the flexible shaft coupler behind it.

Similarly, mount the `Motor_panel_L` with the ball bearing inserted and the second `Motor_panel_contra` onto the opposite profile so that it moves parallel to the first assembly with the motor.

Mount the `Motor_panel_X` with the second NEMA motor installed, together with the `Motor_panel_X_contra`, onto the 2020 ALU profile. This carriage should also move smoothly along the 2020 profile.

Inserting the timing belts with their tensioners is a bit tricky. First, heat-set the small M2 inserts into the smallest printed parts—the belt tensioners. Insert one end of the timing belt into the small belt holder on top of the `Motor_panel_L` part. Then insert the X-axis 2020 profile with the carriage into the `Motor_panel_L` and attach the other side to the `Motor_panel_R`. Do not fasten the X-axis profile with corner joints yet.

Thread the belt under the wheel, over the motor pulley, and under the second wheel of the X-axis. It is recommended to loosen the pulley screws so the pulley can rotate freely on the motor shaft. Gently tension the belt by hand, take the belt tensioner, and place it on the belt so there is approximately an 8 mm gap between the end of the tensioner and the motor panel. Mark the correct belt length with a marker.

After measuring twice 🙂, cut the belt and insert the free end into the belt tensioner. Move the X-axis profile through the `Motor_panel_L` so that the tensioner can be inserted into the groove of the 2020 profile, then return the profile and insert it into the `Motor_panel_R`.

Insert the small tensioning screw and tighten it into the insert in the tensioner. Secure the 2020 profile on both sides to the motor panels using corner joints. Gently tension the X-axis belt and tighten the pulley on the X-axis motor.

Insert the shaft through the ball bearing, mount the second pulley onto it, and secure it in the flexible shaft coupler on the Y-axis motor.

The X-axis carriage should now be fully functional. The entire assembled X-axis bridge should move freely along the Y-axis profiles.

Thread, measure, and shorten the Y-axis belts on both sides of the frame in a similar (slightly tricky) way. Here, the belts and their tensioners are part of the machine feet. Insert the belts into the front feet first, thread them through the wheels, measure the length, cut the belts, insert them into the tensioners, and—by loosening the front feet—insert the tensioners into the 4020 profile grooves.

Then tighten both the front and rear feet and screw in the tensioning screws. Finally, tighten the pulley screws on both sides.

Tension all three belts only gently using the tensioning screws. It is always possible to tighten them further later if needed. Both the X and Y axes should now be fully functional.

I recommend first testing the electronic motor control using loose wires and only after thorough testing shortening the wires appropriately and securing them in the shrink sleeves.

My machine does not have hardware homing end switches. I use it placing the head to desired home position by hand before starting the machine. Homing switches could also be implemented by stallguard homing feature of TMC2130 motor driver if needed.