Hey @stutaylo ! I’m wasn’t 100% sure either, tbh… it was the emboldened ‘zero’ that caught my eye
From what I read (similar articles probably), one danger is that because there is latency in the headphones as the determine the background noise, there is a short period where they generate a not-quite-180° wave, which would probably be summed with the outside noise and therefore be louder.
But it does seem from extra reading that the noise cancellation effect is called ‘destructive interference’ and proper glorious and golden silence is indeed the outcome.
As some companies make active noise cancellation headsets for noisy factory floors, I’m guessing that if the specs are correct and up to ‘code’, these things are safe and effective. Maybe (in bold).
@Gerry haha a good bit of formatting always helps to get the [potentially incorrect] message across…
I have edited my original post to back it off a little.
A lot of the big names do infact make Active noise cancelling headphones for industry or airline pilots, but they are not consumer grade and the cost is pretty significant.
Apologies for getting off topic…
Back onto it though - I’d love to see a temperature comparison between the Cooling system on the CW-3000 that Julien is using, and what the Axiom machines use (Not many photos around but there is one below). I like the way Axiom do it, keeping the whole lot on the gantry its a very compact unit with a little pump, radiator and fan. I have read people having issues if the coolant isn’t flushed often, It does look like a pretty small volume relative to what @julien is using.
I’m on it and actually have sourced the coolant pumps they use. I have a strong feeling they will not hold up for long duty cycles based on previous experience.
“ISOtunes® XTRA comes with 4 sets of TRILOGY™ foam eartips (XS,S,M,L) and 3 sets of silicone eartips (S,M,L). The TRILOGY™ foam eartips are designed for superior comfort, superior noise blocking and superior sound quality. Choose the size that fi ts most snugly in your ear canal. Remember, the snugger the fit, the better the noise blocking. The silicone eartips are intended for use when NOT in noisy situations”
Well my knowledge/memory is skewed, was basing that off what I remembered when i bought the Plugfones, which using the Wayback Machine, my remark is still wrong , both the foam and silicone were rated at 25dB noise reduction. Today, their new plugs are rated Foam: 29dB and Slicone: 27dB
ISOtunes® PRO 2.0 comes with 3 sets of ISOtunes TRILOGY™ Foam eartips (S,M,L) and 1 set of rubber triple flange eartips. The foam eartips have been specifically designed by for use with ISOtunes PRO and are made from a heat-activated memory foam which allows long-term, comfortable wear and enhanced sound performance. The foam eartips provide maximum noise reduction while the rubber eartips are recommended for use in less noisy situations.
According to their product page, (supposedly) Foam plugs are rated at 27 dB NRR, which matches Plugphones Silicone plugs rating. The ISOtunes wired version says 29 dB NRR, matching Plugfones Foam plug rating.
Plugfones ratings don’t change between the wired and wireless version as far as I can tell like the ISOtunes do.
Something is better than nothing? I of course don’t work an 8 hour shift in a noisy environment either, so my concern is less as long as I have some protection.
A ways upthread, @Julien mentioned Mark Pressling’s video on a thermal-switch controlled VFD fan. I had seen that before (and come to the same “well, I’m not going through all that” conclusion), but I had another look anyway. The top comment was a guy who said basically “I put the switch on with a binder clip and it worked just fine” and I thought that was an interesting idea.
Then I came back to this thread and saw @gmack’s suggestion to use thermal-transfer epoxy and I thought that was a really good idea - so I did it. And it works. I didn’t have to disassemble anything; pop the cover off the fan, pull out the fan, do the thing. It was admittedly a bit fiddly getting the switch spliced in since my fan wires were pretty short, but I got it done inside of about 15 minutes.
After letting the epoxy cure overnight, I tested it using a heat gun and it works perfectly. I’ll have to see how it holds up over time, but I’m not expecting any problems.
Did you go with the 50 degree C switch too? My guess is that the fan will never come on because most of the power (heat) dissipated by the VFD is proportional to the square of the spindle current and very little of the VFD’s capability is usable on Shapeokos. But, as @The_real_janderson pointed out, affordable quieter fans (brushless, better bearings, lower CFM, etc.) are readily available.
I went with the 45C switch - that was what Mark used, IIRC and it seemed reasonable to me (based on nothing, I’ll admit. It seemed to me a reasonably low number). I also strongly suspect that, even at 45C, it will not spend a lot of time (if any) on, but I’ll have to see in actual use.
, both the foam and silicone were rated at 25dB noise reduction. 
I of course don’t work an 8 hour shift in a noisy environment either, so my concern is less as long as I have some protection.