I use my Nomad 3 in a soundproof enclosure and have started looking into quiet air blast options to help with chip clearance. Size and noise are my main concerns, so I’m thinking an aquarium pump is my best bet and it looks like this works well for some people if setup correctly.
The enclosure works pretty damn well at keeping the noise down, and I’m fairly sure some of this comes down to it being almost, if not totally airtight. The only place I can think of where air could get in or out is where the cables come in (and potentially the air hose), but even that’s sealed quite well. I tend to run it with the door closed for no more than 30 mins at a time, pausing during longer aluminium and brass jobs to vacuum it out and let things cool down a bit. It gets warm after much longer, but not worryingly so. It’s only 150W after all.
So my question is, is it going to be a problem pumping air into this thing given that there’s no easy way for air to get out? I get that these pumps don’t put out a lot of air, so I assume it won’t turn into a pressure pot. But will it cause stress on the pump? I’ve got no idea about the science here!
I have read about needing a place for air to get in if using a vacuum during, and I guess the reasoning is the same. But a vacuum must move a lot more air than a little aquarium pump.
I have a soundproof enclosure and use one of these for compressed air. It’s by no means silent (as they advertis) but it’s close enough that I don’t think I bother the neighbours in the apartment adjacent to the “workshop”.
There are two concerns here, so be careful:
Chip clearance: You want to get cut chips out of the way of the moving endmill. For this you just need something strong enough to make a little puddle of cleanliness around the endmill. Something as simple as a 12V blower fan might be enough.
Chip evacuation: You want to get the chips out of very tight holes (e.g. if you’re boring) and out of the endmill itself immediately, without giving the slightest chance the chips will get stuck in the endmill (and therefore clog it and ruin the endmill and the workpiece). In this case, you need a reasonable amount of high-pressure air, which is why you see a lot of people using compressors.
You did already say “clearance” but I’m recommending you be careful because while clearance matters a lot for say the Shapeoko folks cutting wood, I think the important thing for the Nomad, at least when milling more difficult materials, is evacuation.
Maybe you do really just need clearance but thought I’d mention it in case.
Actually I’ve found that this isn’t really the case, at least for my enclosure. Mine is a box-in-box setup with MDF boxes lines with noise-absorbing foam. The box, when in operation, is mostly airtight but there are a couple of ~30mm diameter holes that I’m running cables through and there’s a definite “leak there”.
However when the machine is running, I can barely hear a thing coming through the holes, the noise that makes it out is all the low-frequency noise that still manages to vibrate the whole enclosure.
I think what’s happening in my case is that most of the sound that’s generated hits the foam and is absorbed by it, so only that tiny amount of noise that travels directly to the hole in the enclosure makes it out.
In my case I’m using a compressor that goes up to 8 bar and my enclosure has enough “leaks” that pressure doesn’t accumulate so I don’t have any problems at all.
My understanding of the physics is that one of these things will happen:
The pressure in your enclosure exceeds the pressure rating of the pump and no more air is pushed in (and your pump overheats or dies or something). This is likely if you use a weak pump and have a very tight enclosure (but I consider it unlikely your enclosure is that tight, even MDF is porous at high enough pressure).
The pressure in your enclosure makes a leak. This is what happens if you have a very tight enclosure and a very strong compressor.
Your enclosure isn’t actually as airtight as you think it is and the air you pump in is free to escape.
Thanks Lucas, that’s really interesting, I’d never really considered the difference between chip clearance and chip evacuation. I mostly cut aluminium and brass and don’t seem to have a problem with evacuation as you describe it, even in deep pockets, and I’m yet to clog an end mill. Perhaps that’s down to primarily using single flute cutters.
Just so I’m understanding then, chip clearance should only be a real concern in pockets? Presumably when contouring the outside of stock there shouldn’t be any chips in the way? As long as you are getting the fresh chips away.
Yeah mines effectively a box within a box too, but it’s waay over engineered. Plywood for the outside, then a layer of MLV, then 2 layers of plasterboard hanging off resilient channel with rockwool in the gap, then a hybrid MLV and foam layer. Plus soundproof sealant everywhere. The goal was air tight, but who knows.
I suppose drilling a hole somewhere that I can plug easily wouldn’t be the end of the world.
Yep, they’re nigh on impossible to clog. But I’m able to get much higher MRR with multi-flute endmills and those really do need chip evacuation. I’ve tried with and without air blast and without air blast pretty reliably clogs the endmill.
If you only need single-flute, maybe clearance is all you need.
Yep. Pockets and slots are the big problems.
If you have a bit of a ledge as you contour the outside of the stock, the chips can rest there too though.