Welcome back,
I've been working on my ball mill some more, and the main features I have added now is a motor stand that I 3d modeled and printed, as well as a motor speed controller board, that uses a dial to change the RPM.
Let's start with the motor stand. I started off with no knowledge about motor stands and researched the different types, and decided to go with a semi-circular clamp mount. I used onshape to begin 3d modelling, and modeled this first:
A problem with this first model was that the actual rectangles i had modeled onto the semi circle was in line with the semi circle, so when i combined both together, it was more of an ellipse than a circle, so didn't fit. Also, I planned to drill where the bolts were to go, which may have caused problems down the line. The first model came out like this:
After fixing this problem, I continued to print the mount five more times till I got to the perfect one due to fine-tuning the measurements and distances. Here is all of them printed out (I am not sure what to do with them):
(There are only three because I would tweak and print each one and then save it, and then discover a new problem, so making a new file)
What this part of the process taught me is that just because the measurements and theory works out on CAD, doesn't really mean it's going to work out in real life, and that prototyping is essential with these kinds of things.
I was lucky enough to find a Creality CR-10S Pro on Facebook marketplace listed for only £50, which was a priceless investment in my opinion, as I only needed to learn how it worked, tuning and calibration, and fixing a small problem which was a torn Bowden's tube (the tube that delivers the filament to the nozzle). Although it is much slower than newer models, and doesn't produce perfect prints, it's an amazing piece of an equipment I am lucky to have and use, and even let my friends print stuff.
Back to the ball mill, let's move on to the pulse width modulation part of things. I decided to buy a motor speed controller off of aliexpress. I then decided to break it down and understand what it was doing. Here is what it looks like (I broke it because I screwed it in and the screws thread was worn out):
As you can see, there are some capacitors, a potentiometer, heat sinks on top of a MOSFET and some inputs. Essentially, this simple circuit is a MOSFET (high speed electronic switch) constantly switching the current on and off through the motor thousands of times per seconds allowing for some PWM, which changes the speed of the motor, that varies with the potentiometer. The capacitors are there in order to filter electrical noise that's generated from the constant switching and also smoothing any unwanted voltage spikes, allowing for a smoother output to the motor. The blue boxes at the bottom are the inputs for the motor's +ve and -ve, as well as the input voltage +ve and -ve and I just soldered these to the motor.
This is the final product:
The drum is still shaky, mostly due to the placement of the castor wheels, which is very problematic and hard to find the perfect spot, so this will do for now. Another thing I would chance is the actual frame, which has gone through a lot clearly from all of the drilling and screws. The drum is also not a perfect cylinder, which seems to also be problematic, so maybe buying a new one would help.
I plan to recycle electronics parts using this device for valuable metals, crushing old PCBs into a fine powder then using magnetic and density separation to get them out, but would need proper ventilation and safety due to the risk of inhaling heavy metal powders like lead, but would be a nice way to recycle electronics.
This was a fun project and I plan to stop pursuing it from here, and instead would like to push more for electronics related projects, as that is what I plan to pursue in the future. I learnt a lot from this project, such as using CAD, improvising, and most of all, persistence.
Thank you for reading this.
