I built an EDM machine

today we're going to be talking about electrical discharge Machining electrical discharge Machining or EDM is a really exciting way to cut metal with extremely tiny Sparks in this video I'm going to be walking you through all the little technical problems we solve building this non-traditional Machining has been an underdeveloped set of Technologies what they all have in common is that they are low Force processes for the most part which is great if you want to build robots because it means that there are fewer engineering problems to deal with many manufacturing processes require many tons of force which in turn requires many tons of steel to overcome then you're adding in hydraulic actuators in the price of development skyrockets this is a rudimentary EDM Mill built from a 3D printer frame in an EDM power supply for the past few months I have been focusing on optimizing the power supply for affordability which is why you can buy it right now on kickstarter.com the early bird deal for this EDM kit costs less than the typical cost of a mid-range bedslinger 3D printer which is amazing considering that the only other Alternatives range from three to thirty thousand dollars so I have the Ender 3 set up right now as an EDM machine let's get some stock material loaded in this is regular store-bought distilled water it is very important to use distilled water or deionized water when conducting EDM this is because we do not want any electrolysis to occur during the process what I'm going to do now is jog the electrode over to the bottom left hand corner of the work we can also turn on flushing water is entering the pump on the right hand side and then it exits the manifolds on the left hand side so there's always water flowing across our aluminum work [Music] you might have seen these compliant mechanisms this is an ortho planar spring that we designed and fabricated on our EDM machine what's really interesting about a component such as this is that it has no moving Parts in it technically but it's still able to achieve Precision linear motion and there are a ton of these compliant mechanisms out there that are designed to be made with EDM in fact it's almost an exclusive manufacturing process for these in metal right now up until today it's been extremely difficult to prototype compliant mechanisms because of the EDM bottleneck it took maybe 20 or 30 minutes to get this cut out on our machine after designing it so in under an hour you can go from a design in Fusion 360 to a completely fabricated compliant mechanism we cut out lots of little generic mechanical bits here one of the things you can do is create Bend lines in your design here's an example of another component that has been not only bent but stamped stamping can increase the rigidity of components enormously this is simply a 3D print this is a actually just regular polyterra PLA and we can put our component that we want to be stamped inside one interesting possibility is actually making our own electrical connectors everything began just on a breadboard we used a couple of these simple buck boost converters to begin with originally we had considered using ne55 timers as our pwm source but we scrapped that to use a Smart solution we ended up using an Arduino Nano microcontroller this made debugging easy because we could monitor sensors all over with an OLED display speaking of sensors this is an ACS 712 current sensor we found a module on Amazon it contained all the passive Electronics in the actual ACS 712 chip on board it's an analog sensor using one of the analog pins on the microcontroller we can monitor the behavior of the EDM machine after the breadboard phase we ended up switching out the Arduino Nano for a Raspberry Pi Pico the reason for this was documentation and capability they are really under utilizing it considering the number of gpio pins provided this board could be an entire MCU for a Clipper device if you're interested you could probably get it to work that way on a voron edem build breadboards are good and all but we wanted to design a PCB we only had one problem nobody on the development team knew how to design pcbs the solution was for me to take 500 milligrams of caffeine every day for about a week while binge watching Phil's lab in the eev blog these were the first pcbs that I ever designed I ended up ordering it on Christmas Eve at 10 am after staying up all night as the first PCB you could probably do worse it turns out that when you design a circuit board after staying up 36 hours straight you make some mistakes the most critical of those mistakes was completely forgetting about the copper pour for the ground plane those of you who understand the importance of proper grounding know where this is going after switching on the circuit for the first time the delicate mosfet only lasted a few seconds before the high voltage coupled to the gate and burnt them out it was at this point that we conducted Diagnostics and had a meeting on revision requirements we spent maybe a week redesigning the board before we placed another order the purpose of the microcontroller is primarily to switch a power mosfet on and off we originally spec two mosfets to have the temperature reached this turned out to be not required after doing the math we found that the power of switching was about a watt combined with the thermal mass of the large mosfet and its surface area this wasn't an issue we also stopped using these small SMD heatsinks for the same reason I would recommend them for other projects overall the routing on this board was borderline and usable we scrapped the design immediately we also got these boards fully assembled from overseas which I would not recommend again it's faster to just solder them yourself and save a week of time I had been proficient at through hole soldering but I learned to really enjoy SMD work we use HTML bomb for automatic bomb generation so you can just boot up HTML soldering instructions on your phone and solder while you listen to music this is a space I set up for soldering it was originally a bedroom but I have slowly converted every room in my home into a workstation all of these desk organizers are 3D printed and they're part of the gridfinity standard the neat part about this is that there are thousands of designs online you can download for free we also added a port for transferring Digital Data whenever the EDM machine hits a short it will pull this pin low which can be very handy for making closed loop EDM systems a major hurdle we cleared was reducing the cost of power resistors this is a regular power resistor our first design required seven power resistors to function they also cost about 10 to 15 dollars each so altogether the power resistors were going to represent most of the cost of the unit the inspiration for a solution came from desktop 3D printers 3D printer has used PCB hot plates for heating their beds a hot plate is just a really big Power resistor so we had a solution I designed this aluminum PCB and kai-cad you will notice this really long thin copper trace it is folded into a Hilbert curve which is a type of space filling curve three blue one brown has an excellent video explaining the math Behind These I sat down and Liberty calc and did some basic physics to design the PCB I used the resistivity of copper and the thermal coefficient to calculate the length of copper traces required using the thickness provided by the manufacturer this is the finished EDM power supply it's a self-contained unit we opted to 3D print all of the polymer components injection molding was considered but the logistics and Lead times associated with making molds was very high which is ironic because EDM is used to make injection molds conventional EDM machines are so expensive and scarce that mold fabrication becomes an industrial bottleneck in a few years our goal is to eliminate that bottleneck by building better EDM machines the front panel has a few interconnects on it the first is the 24 volt enable Port this is a safety feature to enable the device you need to send it 24 volts over this cable we chose 24 volts because it's used by all modern 3D printers the second two ports are optional they simply provide information about the behavior of the EDM spark gap on the left is an analog output from the current sensor its output is mapped to the EDM current and ranges from 1.7 volts to 0.3 volts finally there is a USB port for making firmware changes to the Raspberry Pi Pico I have popped off the cover there are three sections near the front is the motherboard in the middle is the power resistor PCB with a very large heatsink at the end is the power entry module in DC fan the heatsink on this design is intentionally Overkill you can see that we also have a thermistor here that is another safety feature the high voltage region contains the power mosfet and capacitor array there is also this current sensor it is rated for high voltages and electrical isolation the low voltage region of the motherboard contains all the digital electronics the microcontroller and the voltage of dragulators the duct tier at the end is 3D printed the air is guided over the extrusions maximizing cooling well that pretty much covers four to six months of product development if I missed anything leave a question in the comments down below during covet in the parts shortage we learned how important local manufacturing is we want what happened to 3D printing to happen to EDM we will see a revolution in manufacturing when desktop electrical discharge Machining explodes in popularity the kickstarter will be linked down below if you want to help contribute to that future I would also like to recognize the work of Dominique meffert and Ben Fleming they contributed a great deal over the years to developing EDM power supplies make sure to check out Dominique meffert on YouTube or hack a day as well as purchase Ben's book building a pulse EDM machine if you're interested

Channel: 𝕄𝕠𝕣𝕝𝕠𝕔𝕜

Views: 876,822

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Id: 5CeCxkFVCdM

Length: 9min 22sec (562 seconds)

Published: Sun Mar 05 2023