[jim_stoll]

What is the general PSI required to clear chips from a workpiece? I've got a Taig CNC mill, and I'm tiring of hovering over the machine with a vacuum wand and a can of WD-40... I'm looking at the Spra-Kool Midget Mist unit from Little Machine Shop. I'm told that the min 30psi for that unit will deliver the coolant mist, but likely won't do much to clear chips, so I'm trying to figure out what else to get and/or hook up to clear the chips.

Thanks!

[teamtexas]

30 psi directed at the cutting tip should do a fair job of debris removal. I use a compressor with a 90psi out put but I reduce it down alot at the machine. Not sure of the actual amount being delivered. A small air compressor (pancake style) would do an ample job if you don't want to take the chance on the mist. Put something like a 1/4 inch ball valve at the end to control the flow.

Dan

[Rodm1954]

30 PSI should remove aluminum no worries. I use 20PSI as I do not want to spread the swarf all over my shop. Make sure the air nozzle is close to the cutter and you should have no problem.

[jim_stoll]

Great info - thanks for the help!

I've ordered the 30psi spray unit, and will play around with potentially restricting the airflow a bit to keep from trashing my basement work room!

I'm now committed to sharing my work room with my 2hp Craftsman pancake compressor - there goes my hearing... Anyone have any good tips on reducing the racket a bit? Is there any effective kind of noise-reducing enclosure or such that one can build for the compressor? I generally do my milling at night after the wife and kids are in bed, so I can't locate the compressor in another room or such, as it'd disturb them. Outside isn't an option, as then the neighbors would be waking the wife and kids up anyway, knocking on the door to tell me to cut the racket... :-)

Thanks!

[Geof]

Put your compressor inside a box lined with shag carpet, or other deep pile carpet, and it will cut the noise dramatically. Depending on how hard the compressor is working it may tend to overheat if the box is closed and in this case you have to get a bit more sophisticated. Put ventilation tunnels into and out of the box with carpet covered baffles so there is no straight path in or out and get a bathroom vent fan to draw cooling air through the box. When the sound has to go around many corners and bounce off surfaces that are poor sound reflectors it gets diminished.

[Rodm1954]

Geof is on the money there. Only thing I can add is a rubber mat on the floor or at least the legs to absorb the vibration.

[Geof]

Geof is on the money there. Only thing I can add is a rubber mat on the floor or at least the legs to absorb the vibration.

Hanging head in shame....yes I missed that.

Which is inexcusable really considering I installed a diesel genset in my home shop and had to mount it on a big block of concrete with rubber isolators to stop it bouncing the floor up and down. The noise I controlled with the baffled box...a BIG box!

[jim_stoll]

Heh Heh - if you can build an effective baffle box around a daggone diesel generator, it gives me hope that I may be able to sufficiently quiet my 2hp compressor to the point that I can reach old age with my hearing intact! :-)

[Geof]

Heh Heh - if you can build an effective baffle box around a daggone diesel generator, it gives me hope that I may be able to sufficiently quiet my 2hp compressor to the point that I can reach old age with my hearing intact! :-)

eh, eh, speak up boy!! I can't hear you.

Not to suggest I have reached old age yet but I am closer than you.

[jim_stoll]

Ok, so here's the next question.

Oh, sorry...

OK, SO HERE'S THE NEXT QUESTION!!!! (that better?? :-)

What's the recommended material to make this box out of? 1/4" ply, 1/2" ply, MDF? I was thinking of lining it with pink insulation foamboard in addition to the shag carpet - think that'd help? Also, should this be a 5-sided box (ie, open bottom w/ box just sitting over the compressor on the floor, maybe w/ foam weather stripping along the bottom edge?), or a full 6-sided closed box (such as with a hinged lid or side panel?)

Thanks guys - this is going to be my Saturday afternoon project w/ the kids!

[Geof]

MDF, make it five sided so it will sit over the compressor with a couple of strips of shag along the bottom rim, not weather foam. Have the power cord and air line come out through a shag lined notch. The reason I say this is that you want air to get in for the compressor and the shag is porous but the weather foam is not.

Don't use the foam board it is simply a good reflector of sound. You could use acoustic ceiling tiles, the ones with the random tiny holes. The whole idea is that you want surfaces that are not smooth and not rigid. When the sound waves hit they do not reflect they are absorbed.

Of course if you want to get really fancy go to a marine supply place and get the lead bonded rubber sheet used in the engine housing for boats; many $$$$ per square foot. Works like a hot **** though.

[jim_stoll]

Ah, good point - guess the compressor needs to get its air from somewhere, eh? <:-)

Boy, if this works well, I may even make a little insulated box neighborhood or condo and try to quiet my shop vac, too!

Thanks Again!!

[Geof]

....try to quiet my shop vac, too!

Thanks Again!!

Here is a trick for the shop vac, depending on the style. Most times you get a circular brush nozzle in the kit of nozzles with the vac. Put this in the outlet hole and it will cut the noise to some extent. A lot of the noise from a shop vac is the turbulence generated in the high speed air flow as it interacts with the sharp corner on the rim of the outlet.

[Rhodan]

A bit late but as I work around all sorts of air compressors I've learned one important thing.

The really small air compressors use a direct drive with a tiny piston that goes like a bat out of hell. While less expensive to manufacture they have two problems:

1) Noisy as hell with high frequency noise that is well suited to damaging human hearing.

2) Cannot handle continuous duty as they often use plastic bushings that soften and slop around when heated.

If you get fed up with that compressor, start looking for belt driven ones. They usually use a larger piston (slower RPMs, lower frequency noise and a lot less of it) and for real metal bushings or even ball bearings. They're usually quiet enough that you don't need any kind of enclosure at all and can talk normally right beside them and still be heard by someone beside you.

I've seen small belt driven compressors run continuously for weeks (air leaks in control systems) with no adverse effects. On the other hand, I recently had to use a 5HP direct drive as a stand-in for a 3HP belt drive on a swimming pool control system (modulating valves). Within two hours the poor thing could barely make the 125 PSI cutoff. By the end of the day it was running continuously just to stay above 110 PSI.

[jim_stoll]

Yeah, for its size, this little compressor is really quite loud. I've worked in auto shops before, where it was easier to hold a conversation in the same room with a large compressor than it is with this smaller one, and as you say, the higher/shriller frequencies are more prevalent w/ the smaller one, too. But, that's the one I've got, and will be the one I'm stuck w/ for a while to come - at least until it self-destructs. :-) I'll definitely take your advice and keep an eye out for a belt-drive down the road though.

[mxtras]

For what it's worth - a yoga mat (Wal-Mart, E-Bay) is a source for good vibration absorbing material. I don't think it will absorb a lot of sound, though.

I have a small regulator mounted to the head of my Bridgeport and it's regulated down to between 10-15PSI with the two nozzles open. It's quite annoying but it does the job.

Scott

[teamtexas]

I would use MDF for the box and some type of rubber gasket at the floor to keep moisture out of the wood. Don't forget the compressor needs to breath. You need some type of air inlet. It will also heat up while running so you need to account for that. The carpet or insulation sound good for sound deadening.

Dan

[nine 16]

Somewhat related to your sound attenuation challenge.

I've build a couple of bullet traps for test firing pistols. While both included the necessary snail-style decelerator at their core, the first unit was surrounded by by a pink insulation-lined plywood box with the actual steel decelerator suspended in the middle. The second decelerator was surrounded by a welded steel enclosure without being insulation-lined.

I can definitely say that trap with the steel enclosure was much more quite. I attribute this to the stiffer wall material being less able to communicate internal sound to the outside. In other words, the steel walls of the box could less easily act like the diaphragm of a speaker. I remember seeing the walls of the wood enlosed trap pulse outward with each discharge - that pulse generated an external sound pressure wave that was interpreted by my ear (and anyone elses nearby) as sound. The wood enclosure worked ok, but I wanted it quieter.

In essence, with the steel enclosure, I made a firearm suppressor, or moderator, and many of you have experience with how a proper silencer can tame the roar of a firearm.

In short, and all things being equal, I'd say the stiffer the walls of your enlosure the better.

My 2. Later.
-Mark

[Rhodan]

Makes sense '9. Many stereo manufacturers choose MDF for speakers and its not just because of the costs I'd wager.

[Smitty911]

You can also use the trays from Eggs. Staple them to the inside of the wooden box.

I work at a place that does EMI, EME, etc testing and they use a treated foam shaped like pyrimids to control, sounds and electricial waves.

Smitty