Final polishes

Made the BOM, in google sheets then exported to CSV and into a .MD format to paste under the readme. I totaled the price from all the online stores together and took screenshots in order to submit. I also wrote the readme and uploaded project files (PCB, CAD assembly, etc.) and made a diagram. I also made some renders and did some small fixes in the design. Overall, polished up and made it ready to submit.

Made ebox and hv-box

Took me ages but I finally got it done. I finished the entire CAD with an ebox (power supply, control board, drivers, etc.) and then the hv-box which is basically a DIY NST. It outputs 50KV continuously, not pulsed which is super cool. I decided to put them separately because the enclosure for the power supply is grounded. Which means that it will try to arc to it and destroy everything which would be bad. I think I'll put like a copper mesh or chicken wire on the bottom of the engraver itself and then ground that for the single electrode discharge, and then for dual electrode discharge I'll ground one of the electrodes.

Finished power supply PCBs

I made both the flyback driver (single MOSFET based, not a ZVS driver. this is for adjustability and testing purposes). I also made the voltage multiplier and limiter to make a steady current flow of 50kV+. It shouldn't look like a taser. For the engraving and etching purposes, it theoretically should just be a beefed up flyback output.

Finished power supply schematic

I'm actually journaling from last night since I fell asleep but basically I started out by designing a full PWM controller, which I finished. But then I realized that I should only be able to adjust the frequency between 5kHz and 35kHz, so I thought I could put a base resistor and a potentiometer together. However, there is also a timing capacitor and a second resistor involved in the oscillation of the 555. So I deleted the PWM controller and made an adjustable buck converter to feed into a ZVS driver. But then I found out that they are resonant based on the voltage so that wouldn't work and I had to delete it once again. Finally, I decided to use a cheap signal generator to drive a MOSFET, which then drives the flyback transformer. This allows a very simple type of control with adjustable power to the flyback as long as you don't set it to like, 1Hz or 300kHz. I then developed a short 4-stage cockroft-walton multiplier. This raises the voltage to a usable amount for the corona discharge etching I plan to do (at around 50kV) and also creates a single positive voltage potential. Adding a high voltage resistor allows the current to flow smoothly and not in the 'taser-like' style. Which means that I can use it in both configurations of dual and single electrode to ground.

Brainstormed power supply design

Decided to go with a 555 based driver for the flyback rather than a ZVS driver since I want it to be easily controllable.

Also, indicator lights, filters, and resistors in order to keep the output smooth and steady.

Made head + polished up

First, I created the guiding part on the x axis to move the head itself and a belt clamp to go along with it. I then added this interesting magnetic z-axis system that I've been thinking about. Basically the guide is plated with machined steel (from my school's CNC or my own if I manage to build it in time) and the toolhead itself has a radial neodymium magnet on it. This allows me to adjust it up and down incrementally without large screw based systems. I then added the head itself which has magnetic hotswappable electrodes (to swap from a dual electrode plasma arc to a single HV positive potential to ground). Finally, I polished it up with end caps for the rods, limit switches, supports, etc.

Made x-axis

First, I swapped out the linear rail setup from yesterday for v plates. I added some bearings (linear as well) and some linear rods. I also put support bearings in order for the shaft of the steppers to not get bent. All that is left in the motion system of the machine is to make the toolhead (where I think I will add hot swappable tips.

Started working on x-axis

I started putting the bearings, idlers, pulleys, and motors on the linear rails in order to start on the gantry and x-axis of the machine. However, it feels janky and not sturdy enough. I think this is due to the thin footprint of the linear rails themselves, which gives me an idea. I wonder if I can get rid of the linear rails and replace them with v-slot wheels. This would be cheaper, and also allow me to place a larger gantry without the jankiness. I think I will move ahead with that instead in order for it to be reliable enough for the extensive testing I wish to use it for.

Made the y-axis

Made the frame out of 2020 extrusions and some corner brackets
Dual steppers for the y-axis
Added double shear for the idlers and motor
Made mounts for everything
Designed belt tensioners on the idler side

The y-axis is basically finished, might need some minor tweaks later though

Research

There are a few goals I want to achieve with this machine.

-Adjustable 50kV positive voltage potential (At the moment, 50kV seems to be a solid amount but I might increase it to 100kV later down the line)
-Sharp tungsten electrodes with adequate grounding for high amounts of discharge
-Ozone ventilation (the machine produces a lot of ozone)
-Neon bulbs (i would like to use gas filled bulbs as indicator lights etc and also larger gas tubes)
-Modular toolheads in order to change discharge shape
-Water electrolysis (oxygen production) to fuel the discharge possibly
-Audio modulation in order to make the machine play music with the plasma

I would like it to be a nice proof of concept to demonstrate that corona discharge engraving (which has not been done before) is a viable alternative to other methods such as lasers and hot wires.