Homemade Vacuum

This project started out because I had an extra 775 DC motor lying around (worth about $20). You could say I went deep down the rabbit hole here.

When I bought my CNC 3018, a small tabletop hobbyist CNC router, I knew nothing about routers and wood working. It was an impulse buy; I've always wanted to make my own wooden keyboard case and there was a sale on the 3018. I quickly learned that this thing makes a lot of dust, some wood dust can be pretty toxic, and proper dust management is mandatory. I also learned that a proper woodworking dust collector was gonna run me at least $1k (or ~$500-600 if I'm gonna be super cheap about it). Since these shop vacs take up a decent amount of space and I live in a townhouse with not a lot of garage space (plus this is a hobby machine, I'm not trying to start a shop), the full dust collection system wasn't going to work anyway. For the first few projects, I managed by sitting next to the machine with a small corded handheld vacuum cleaner. It turns out most vacuum cleaners can't run for long periods of time; they typically have higher HP and will shut down after long continued stress. Which doesn't bode well for me - these hobbyist routers can only go about 0.5-1mm depth per cut (read: takes FOREVER).

Fast forward a few months, I got fed up with the stock spindle motor and decided to upgrade to something that's sturdier and has a wider z-range. That stock spindle - the 775 DC motor - was sitting on my desk as I was once again searching for a solution to my dust problem. That's when I realized that (1) vacuum cleaners rely on a motor, (2) there's a motor on my desk that's literally built to run for long periods of time, and (3) I should have everything I need to fabricate a vacuum. So I spent about a week between researching, designing, and 3d printing.

The physics behind it was simple enough. There's a fan (turbine really) that attaches to motor; the housing needs to be designed in a way where the air is forced out of an exhaust port lateral to the fan. This decreases air pressure in front of the fan, effectively creating suction in that area - or whatever small opening is connected to that area, like a hose. The first part was the fan design. I tried several of my own creations, but they all snapped when the motor RPM is cranked up. The 3d-printed plastic wasn't rigid enough; some other material might've worked. I eventually came across this beautiful design on thingiverse that had enough rigidity even when 3d printed with PLA filament. I made some modifications and built the housing around that. The dust separator was also adopted from someone else's design from thingiverse, but they're all based on the widely-popular cyclone separator - reduced air pressure at the hose sucks things in, but there's a wall preventing most of that dust from making it to the fan. (not all though, that's why we have filters at the exhaust end). The heavier stuff falls into the bucket and won't go anywhere because, well... vacuum.

The neat thing about having direct access to the motor power is that I can use the existing connection on the CNC machine to automatically turn on the vacuum when it starts milling.