The process of constructing our DIY wood etching machine was split into 3 different phases, as we moved from assembling the main structure of the machine, to editing Marlin to equip the 3D printer with new wood-burning functions, and lastly fixing the main pyrography kit onto the machine.
#1 Main Structure
SKELETON
Being provided with a deconstructed 3D printer, one of our team members painstakingly re-assembled it over the span of 2 full days in the lab. Certain original components of the 3D printer were removed or replaced, such as the extruder, nozzle, and heater. Additionally, an Arduino board and LCD screen was also attached to the reconstructed 3D printer.
This presented us with a bare skeleton of a 3D printer which we could customise for our team’s specific needs.
PEN HOLDER
Secondly, a heated rod holder was designed based off a 3D-printed pen holder that was available in the MnT Lab. Taking inspiration from the original pen holder, our rod holder was redesigned such that the hole would be large enough for the pyrography pen and an additional spring loader to be attached for greater stability. Similar to the pen holder in the MnT Lab, the back of the pen holder was designed to be attached to the extruder carriage by screws.
Additionally, a spring loader was implemented into our design. 3 springs were added to two 3D-printed parts fitted to the pen as well as the pen holder, creating a spring platform. This allows for greater stability during burning of the designs. Furthermore, the springs will compress to prevent the pen tip from breaking upon excessive pressure.
EXTERNAL BOX
Thirdly, an external box was constructed, consisting of a metal frame reinforced with aluminium, as well as acrylic panels. This ensures that the external box remains sturdy. However, this is not just for the aesthetics. To counter the problem of inhalation of fumes during the burning process, we purchased an external fume extractor, which has a tube that extends into the frame to help remove the fumes. The external box allows for burning to take place in an enclosed area, and helps to increase the effectiveness of the fume extractor.
#2 Coding
With regards to coding, the most work and effort may have gone into this phase of constructing our machine. Marlin firmware was used to control the 3D printer. We started with the default Ender 3V2 configuration source code, which is an open source Marlin-based firmware provided by Creality. This served as a base, allowing us to avoid writing the firmware from scratch. We enabled the required functions of Marlin for wood burning, and the unnecessary functions of the 3D printer were either modified or disabled. In addition, we added an Arduino Mega 2560 paired with a RAMPS 1.4 board using the EFB (Extruder-Fan-Bed) configuration.
Image To Code
Additionally, we had to learn how to convert an image into G-CODE to be processed by Arduino, such that users are able to upload digitally whichever design they wanted to be etched into the wood. We made use of InkScape’s “edge detection to extract the outline of the image. Afterwards, JSCut would be used to convert the outline of the image into a set of G-CODE instructions. The G-CODE file would then be uploaded into Pronterface, which then sends the instructions to the Arduino.
Buzzer
To improve the safety of our machine, we installed a buzzer which would sound off at high temperatures (e.g. above 500C), which alerts the user of potential overheating. The components of the buzzer include Arduino Mega, a Breadboard, active buzzers, thermistor, 10k resistor, and wires. The 10k resistor is used as a potential divider, and the buzzers are connected in parallel.
#3 Pyrography Kit
Instead of using the existing heating element and thermistor that a regular 3D printer provided, we would separate this section of the wood etching machine by combining the skeleton with an external pyrography kit. A pyrography kit was purchased from Shopee, which would serve as our external heating element. Some specifications of the kit are as follows: 220V input voltage, 3V output voltage, 60W power, adjustable voltage range of 0-220V, and temperature range of 0C-800C.
Why?
By using an external pyrography kit, this helps to increase the control that users will have over the temperature of the rod, and serves as a safety feature.
Firstly, depending on the type of wood used, e.g. softwood versus hardwood, the temperature control is crucial for the best quality of wood burning. Softwoods, such as spruce and pine, typically take a shorter time, as well as lower temperature to burn and etch a design as compared to hardwoods, such as oak and mahogany. Upon our own testing, we found out that we could burn pine wood panels at a lower voltage (of the kit) of around 90V, whereas oak panels had to be burnt at a higher voltage of around 150V.
By installing an external heating element which can be manually controlled by the user, it allows the user to find the most suitable temperature that is required by the type of wood and design which they are aiming for. The external heating element is equipped with a variable resistor, allowing the user to adjust the voltage supplied by the machine, and hence adjust the temperature that the rod would be heated to. Furthermore, this helps to simplify the functions of the wood etching machine, making it more user-friendly, as users are not required to edit the Marlin code to set the temperature that they would like to use for the burning.
Lastly, an external heating element would allow for the power to be killed whenever necessary, such as when the heating rod becomes red hot. This would allow for the rod to cool to a safe temperature before continuing the design, without having to stop and restart the whole etching process.
Experimenting With Pen Tips
Our machine is designed to have the heated rod positioned vertically above the wood, in contrast to how the pen is usually held at an angle to the wood in manual pyrography. Upon multiple rounds of manual testing, we noted that the original tips that came with the pyrography kit were not able to produce burn marks that were smooth, and the rod had to be held at an angle to be able to burn the wood properly.
We purchased a new set of replacement tips that essentially had a metal ball-like attachment, which was more suitable for automated wood burning. The round tip allowed for more even streaks and burns to be made on the wood surface. The photos below show the differences in the sharp tip (left) and the rounded tip (right). The original sharp tip produced lines that were often choppy, and did not burn evenly on the wood; the rounded tip could produce much smoother and even lines on the surface.
The rounded tip also eliminated the problem of having to hold the heated rod at an angle, where the original problem arose due to the ergonomics of human-controlled pyrography equipment. The heated rod can now be held vertically (or at any angle) to be controlled by the machine, due to the even heating around the ball tip.
Experimenting With Wood Types
From further research, we determined that the wood that is suitable for the burning should be unfinished and untreated to prevent toxic fumes from being produced during the burning. Additionally, softwoods should be used as they burn faster and at a lower temperature, which is crucial for safety concerns, and helps to increase the efficiency of our machine. We have thus picked untreated pine wood panels as our desired type of wood to burn on.
#4 Other Considerations
A manual kill-switch was chosen for our machine, over an automatic one. As mentioned above in section #3, this decision will greatly improve user experience, as they are not required to edit any code to set the desired temperature. For instance, if the user is attempting to burn a design on a thicker piece of hardwood, a much higher temperature is required, which may be hindered by an automatic kill-switch that switches off the machine when the temperature of the rod gets too high, yet the user’s desired temperature has not been reached.
Hence, to ensure safety of users while using the manual kill-switch, we attached a buzzer and an external thermistor to the machine. When the thermistor detects temperature above a threshold limit, it will cause the buzzer to sound off, prompting the user to turn off the heating tip or lower the temperature and let the machine cool down. Visually, when the pen tip gets red hot (but a temperature is not considered dangerously high), the user can also choose to switch off the heating element, or lower the temperature to prevent sparking from occurring.