So I wanted lubrication for cutting Aluminium on the Nomad and MQL seemed the way to go but I wanted it to be as uninvasive as possible, because my Nomad is in my apartment. That means:
- No loud noises (like a compressor)
- No pungent smells (like WD-40 or alcohol)
- No “interesting” chemicals in the coolant
Which was a bit of a challenge. To make it worse, I wanted it to be easy and relatively cheap. I didn’t want to have to machine a pump from scratch and I didn’t want to have to program an Arduino or something.
TL;DR: I use:
- An MQL nozzle (this one, though I don’t think it matters): 55€
- A “smart” peristaltic pump from Alibaba (this one): $126
- An (actually) quiet compressor, the Bambi BB-8: 300GBP
- Accu-Lube for lubrication: ~$50/L from my current supplier
However you can use a cheaper pump and a louder compressor to add MQL for ~$70.
And here’s a basic demo.
Some things I learned along the way:
- “Quiet” compressors aren’t really quiet (unless you pay for it). I ordered a “silent” Sorotec/Implotex pump, which despite lots of claims about “quiet”, “silent”, “totally fine to use in your apartment” and even a very specific “40-60dB” rating for noise, actually ended up being ~70dB and utterly unacceptable.
- “Real” MQL systems are expensive. I looked at Accu-Lube’s own pumps and the quote I got was well over $1k.
- Never use UPS. I actually had to order two Bambi compressors because UPS managed to spectacularly mess up the first one. First, they lied about trying to pick up the package three days in a row, then they delayed it for “security” processing and finally, they delivered it with a big chunk of the packaging itself completely missing, on its side (not okay for this compressor). Fortunately I got them to pay for it.
I think the most interesting thing though is the pump. When you’re using MQL, you need to be able to dispense very small amounts of liquid into the nozzle very consistently, which is a bit of a niche use-case. Most pumps are made for much higher flow rates and MQL needs on the order of 0.5mL/min.
I looked at the cheap obvious stuff and plant watering things and the like had flow rates way too high.
I looked at the commercal systems and they usually use an air-driven frequency generator or a specialty piston pump. They also cost $$$.
I also tried just using gravity and put my MQL nozzle’s hose into the Accu-Lube bottle and siphoned out the lubricant. That did not work well, the flow rate was waaaay too high.
I looked around for alternatives and found some cool projects, like a DIY piston pump machined from scratch and it that was my number 2 but I was thinking that surely there should be an easier way.
And that’s when I found peristaltic pumps. These are very simple devices. Basically it’s just a wheel that squishes liquid through a flexible tube. You can control the amount of liquid dispensed by controlling the speed of the wheel and the diameter of the tube. They’re most commonly used for medicine (where precision and consistency is important) and for hazardous or difficult substances. AliExpress would also have you know that they can be used for watering plants and making cocktails.
They’re fairly easy to DIY, you can do it with a stepper motor (or brushless), a Arduino, a 3D printer, some silicone tubing and a few bearings. You can also buy a basic module with a brushless motor for ~$10 from AliExpress.
However I wanted something flexible but was too lazy to build it, so I paid ~$130 for the nicer “smart” pump from Alibaba, which has a nice interface with speed control and a bunch of attachments for different tube diameters (and hence flow rate).
Anyhow, that’s enough ranting from me. I’m happy with my new MQL system.