Epilog laser cutters are amazingly handy for cutting/etching plywood, acrylic, and other materials. However, while that's all well and good, their role as minimal techno production machines is widely underrepresented. It's time to fix that.
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Step 1: Equipment Overview and Setup
As for all of these projects, if you'd like an overview of the equipment being used, check out the main project instructable. Here I'll just be outlining my hypotheses about what we'll be picking up with each mic type while doing this.
- Condenser Mics - Much like the Objet, while this bed size is great for laser cutting, it's not so great for the gigantic shotguns I have. So, we'll be going with the MKH7040 cardioids again. Due to the fact that there's an active ventilation system in the cutter, I highly doubt we'll get much here since we're basically putting the mics in a wind tunnel. Always worth a shot though.
- Contact Mics - I hold more hope for contact mics. While I'm not sure we'll be able to pick up much of the sound of the laser cutting thru material, there's lots of interesting motors in the system that should provide us with some nice sounds
- Induction Coil Mics - Even before trying this, I'm already pretty sure the cheapest, simplest mic will once again win the day. Due to laser cutter basically being a way to control a motor and laser power through pictures, that means we'll have lots of interesting signals happening all over the machine. Combine that with the head moving based on width for rastering and we might even be able to turn the epilog into an instrument! Assuming you're cool with instruments that would make for a Raster-Noton release.
As you'll see in the follow steps, location of the recorder and mics was a bit of an issue with this recording. Initially I was planning on putting my poor 722 in the bed of the cutter. This was not an ideal situation, as not only could I not adjust levels and settings easily, I also am not real fond of the idea of my recorder and the laser meeting each other.
Luckily, there's enough space under the door to fit cables! So I was able to keep the recorder outside next to the machine. For running cables, I just blue-taped to the inside/outside of the machine where possible, which worked fine.
For the recording, I ended up cutting the same thing multiple times in order to keep similarity in the recordings. I tried to combine raster and vector cutting to cover the full timbral range of the machine. I used the first prototype of the headphone holder for the display units that would hang in the AiR Gallery Show, which involved both a raster icon and some piece cuts.
Step 2: Contact Mics on Materials Being Cut
In order to get the sound of the material being cut by the laser, I mounted contact mics directly to the plywood being cut. Plywood is not exactly the most resonant of materials, unfortunately.
Most of what is heard is the vibration and noise caused by the ventilation system. Even filtering that out, we're still not getting much in the way of interesting sounds. Ah well.
Step 3: Condenser (Cardioid) Mics
(Pictures missing because I can't find the sdcard they're on. Word to the wise: Always upload your pics RIGHT after you take them. :c )
Same problem as the contact mics. Turns out lots of air whooshing through an enclosed space makes for a difficult recording environment. Who knew.
You get a bit more of an idea of what the laser sounds like, but the ventilation is still way, way too prevalent, and no noise reduction plugin is going to fix that.
Step 4: Contact and Induction Coil Mics on Laser Rail
The problem with the induction coil mic ended up being the static positioning of it in respect to the laser rail. The laser moves, the mic doesn't, so things get quieter. Sure, it's kinda neat, but why not have the mics move along with the laser?
Once again, there's the sound of the ventilation system, just no getting away from it for anything that's going to involve air or vibration. This time we get some motor sounds and some nice resonance from the machine.
Step 5: Induction Coil Mics
So the air from the ventilation system causes acoustic mics to be too noisy, and rattles the workpiece too much for contact mics to work. Time to cut out acoustics altogether and go for electrical fields!
I used two induction coil mics, with one near where the motor for the laser rail is on the side of the machine, and the other as near the laser unit itself as I could figure out on the back of the machine.
This worked very, very well.
The laser rail provides the low frequencies while the laser itself provides the higher ones. The first 5 minutes is the rastering of the printer icon, everything after that is vector cuts, though you can hear more interesting noises from the motor at that point. I cut it after a couple of vector cuts because they don't vary much after the first couple, but left the whole rastering process in because I LOVE IT.
Step 6: Conclusions
Ventilation systems: sure, they make sure you don't flood the workshop with possibly toxic smoke, but boy do they make life difficult sometimes. It's like the designers of the laser cutter didn't even THINK about someone trying to record in the thing. Jeez.
Either way, the induction coil mic recordings work great as a core for the sound of the machine, and the rail and condenser recordings can be put way far down/back in the mix to provide some attachment to acoustics.
Now time to start making custom images to raster and have an Epilog Dance Party!