Appropriate air supply for CNC Machine?
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    Default Appropriate air supply for CNC Machine?

    So obviously this is listed in the specs of the machine (looking at a HAAS Super Mini 2) and states the machine requires 4 CFM @ 100 PSI. I've had a couple people in the industry tell me there's no way a 60-80 gallon DeWalt or Porter Cable compressor will keep up. The ratings for these are up to 24 CFM @ 175 PSI that I have found for $2,500. Versus the full industrial style $5k options.

    We are a company that focuses mainly on the software side, but fabricate the prototype parts for systems in development. So I can't imagine any scenario where we have multiple machines and 3 people standing around using pneumatic tools.

    I am just trying to make sure I am not overlooking any variables.

    Appreciate any insight.

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    24 CFM will obviously be enough for a mini mill.

    As to the rest- Dewalt, Porter Cable, Kobalt, Craftsman, etc are all cheap consumer grade compressors. Right at home in any garage.

    They will make air, but they will fail early with continuous duty. There isn't really any brand advantage over HF on that class of compressor.

    What the machine wants is clean, dry air. How you get there is up to you.

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    Can't over-stress dry. Get one with a dryer.

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    If you are going to be using the machine for more than a few hours a week, get an industrial grade compressor. And I absolutely agree , you need a dryer no matter what you get.

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    Depends on how often you will do tool changes. It helps a lot if you get a nice sized tank as a good reserve. 50 or 100 gallon.

    I am gonna get flamed for this but machine tool builders are way to generous with your air consumption. They set the spindle purge so damn high they think your spindle is upside down in coolant 24/7. Compressed air is one of the most expensive energies in the shop. A small shop with 5 or 8 milling machines with these crazy air purges really add up to a lot of money. Some of my machines have the tamper proof regulators for the spindle purge. I just cut the seal and bring the pressure down to a more realistic level. Ok rant off.

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    My air story.

    The motor on my big compressor shorted out. I don't even know what the
    specs are on it. Its a real compressor, 5hp 220 single phase, 120 gallon tank.

    So I ordered a new motor and went to my back up compressor. Problem was my
    crappy little backup wasn't enough.. So off to that Horrible store that sells
    Freight and bought my self a 2.5hp, 21 gallon compressor, 5.8cfm or whatever, $150.

    That POS compressor ran everything. 2-3 mills that claim they need 15cfm, and
    an air hog lathe that runs an air chuck, air tailstock and air over hydraulic for
    the turret.

    I've been running POS compressors for 4 years now. I'm on #3. The last one
    has been going strong for 2 years or so, apparently if you change the oil in
    them, they last a lot longer.

    The $400 motor I bought for my big compressor is still sitting on the compressor,
    I haven't wired it in, or even bolted it on yet.

    One thing having a little compressor will make you do. You will find and fix
    every single little leak you have, the ones you don't even care about with a
    big compressor. Its nice coming in Monday morning and still having some air
    pressure in the system.

    My electric bill went from about $500 a month to about $220 a month (I know at
    least $40 of that was lights I got rid of).

    I only run the pressure I need now, I cycle about 95 to 115, no need putting 140 psi
    in the lines when you don't need it. I run 2 extra 20 gallon accumulator tanks.

    Sand blasting is futile, if I have a big job to sand blast, I just bring it down
    the street anyways. Using air tools is not fun, but I very rarely use them, and
    when I do, its for a quicky 30 second thing.

    I'd love to have a nice fancy screw compressor, but I really don't need it when
    a $150 POS does everything I need. If I had an air purge spindle, I'd probably
    have to fix the big compressor, and I'll get to that someday anyways.

    Air is F'n EXPENSIVE!!!!!

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    Quote Originally Posted by Bobw View Post
    Air is F'n EXPENSIVE!!!!!
    Yes it is. I make a habit of walking around the shop when none of the machines are running and listening for leaks. A stupid leaking air gun for $15.00 will cost you $40 in air every year. Any leaks no matter how little need your attention!!

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    Quote Originally Posted by fmari --MariTool- View Post
    Yes it is. I make a habit of walking around the shop when none of the machines are running and listening for leaks. A stupid leaking air gun for $15.00 will cost you $40 in air every year. Any leaks no matter how little need your attention!!
    One of those Flir clip on thermal imagers for your phone will pay for itself in a heartbeat between compressed air leaks and air leaking from outside into the shop or vice versa.

    Sent from my SM-G973U using Tapatalk

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    Quote Originally Posted by fmari --MariTool- View Post
    Depends on how often you will do tool changes. It helps a lot if you get a nice sized tank as a good reserve. 50 or 100 gallon.

    I am gonna get flamed for this but machine tool builders are way to generous with your air consumption. They set the spindle purge so damn high they think your spindle is upside down in coolant 24/7. Compressed air is one of the most expensive energies in the shop. A small shop with 5 or 8 milling machines with these crazy air purges really add up to a lot of money. Some of my machines have the tamper proof regulators for the spindle purge. I just cut the seal and bring the pressure down to a more realistic level. Ok rant off.
    where do you set your pressure for the purge? I had a little compressor (3h 25gal tank) on my fadal and if the spindle was on the compressor was on. So i got a 240v 5h 80gal 2 stage and that seems to be running about half the time the spindle is. I just can't see the purge needing that much air.

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    The poster did not really give out enough info ...

    I can run 4 Haas mills all day long on a single 1HP Emglo twin tank compressor... it well not run the lathe and all 4 mills at one time ... But here is the kicker ,,, the same compressor could not run the Doosan DNM5700 by its self ... bottom line is that some machines use a lot more air than others do ,,

    I have a 120 gallon industrial 5 hp compressor but 99% of the time I turn it on in the morning just to fill the tank then switch it off and run the little Emglo all day ,,, its quiet and do to being a constant run ,, when its not compressing air for the tank it holds the intake valves open and just pumps air in and back out ,,, That keep the pump cool and the air never gets hot and no water in the big 120 tank ..

    one nice thing about the older "US" made emglo pumps is there super easy to work on and cheap ,, I do oil about every 3 or 4 months and valves about once a year ,,

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    Quote Originally Posted by pcasanova View Post
    where do you set your pressure for the purge? I had a little compressor (3h 25gal tank) on my fadal and if the spindle was on the compressor was on. So i got a 240v 5h 80gal 2 stage and that seems to be running about half the time the spindle is. I just can't see the purge needing that much air.
    20200117_235021.jpg

    I like Franks idea of dropping pressure too. I got this little one from mcmaster and put it inline to spindle air seal. Works fine.

    I run my small shop from a 1946 2hp Brunner piston compressor. I love this thing. They dont make them like they used to thats for sure. The brunner is super quiet and rated for continuous operation. I have this in series with a larger 5hp 80gallon so if I ever exceed the capacity of the brunner, the larger one cuts in as well (very rare). This setup works great for me. Great way to save on electric demand if you run off a small service too. Only use the power when you need it.

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    Keep an eye out for going-out-of-business auctions. Every little shop in the world that is closing has an air compressor that was probably working...maybe even spare parts, too! Good luck!

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    Get the cheapy HF or HD compressors, I've been using a Husky 2.0hp 30 gallon tank compressor with 2 fadals, a Makino, an air drawbar on a BP, multiple leaky fittings etc for 4 years now. The only issue I had was running low on oil, adding oil fixed that.

    If you don't think that's going to be reliable enough, buy 2 of the HF or HD compressors, plumb the tanks together so you have 60 gallons capacity, and use only one compressor, when that craps out after a few years, plug the other one in.

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    Quote Originally Posted by mmurray70 View Post
    20200117_235021.jpg

    I like Franks idea of dropping pressure too. I got this little one from mcmaster and put it inline to spindle air seal. Works fine.
    Just a little disclaimer guys. Do this at your own risk. I've only been machining for 30 years so what the hell do I know.

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    Quote Originally Posted by mmurray70 View Post
    20200117_235021.jpg

    I like Franks idea of dropping pressure too. I got this little one from mcmaster and put it inline to spindle air seal. Works fine.

    ......
    Quote Originally Posted by fmari --MariTool- View Post
    Just a little disclaimer guys. Do this at your own risk. I've only been machining for 30 years so what the hell do I know.
    For those with machines or spindles under warranty, messing with the air purge could cause you trouble if you need a spindle under warranty.

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    I am also running a Harbor freight 21 gallon 125 dollar POS on a Mini Mill 2. I use harbor freight air dryers and water traps too.

    You will most definitely have to clear the water trap, change the desiccant in the small dryer and purge the "industrial style" dryer every other day but no problems yet.Process will take a solid 15 to 20 mins a day but I am anal about dry air. I use 3/8 hose and standard 1/4 fittings if that matters.

    One downside is that I cannot use the air blaster nozzle for too long or I'll alarm out. That does suck big time but I will be fixing that soon.

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    Here is a member of our forum known as Superunknown


    Warning on the language for the snowflakes...

    A discussion on the CFM ratings of the compressor and the air tools.

    Turns out the tool use is in CFM of COMPRESSED air.
    The scumbag compressors are rated for CFM of the INLET air.... !


    YouTube

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    My 3220 VMC cycles tools just fine using my HF 20gal. Wouldn't try to use air blast though.

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    Quote Originally Posted by Agfrvf View Post
    My 3220 VMC cycles tools just fine using my HF 20gal. Wouldn't try to use air blast though.
    When I need an airblast, I just take a second HF POS compressor and use that solely for the air blast,
    usually with an accumulator tank or 2... I also take the time to program my air blast for only exactly
    when its needed, instead of turning it on and leaving it on.

    I really need to take the time to get my big compressor running again.

    Another plus for 21 gallon POS HF compressors. Its like paying half price
    for an accumulator tank, and you get a free compressor on top of it.

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    Quote Originally Posted by fmari --MariTool- View Post
    Depends on how often you will do tool changes. It helps a lot if you get a nice sized tank as a good reserve. 50 or 100 gallon.

    I am gonna get flamed for this but machine tool builders are way to generous with your air consumption. They set the spindle purge so damn high they think your spindle is upside down in coolant 24/7. Compressed air is one of the most expensive energies in the shop. A small shop with 5 or 8 milling machines with these crazy air purges really add up to a lot of money. Some of my machines have the tamper proof regulators for the spindle purge. I just cut the seal and bring the pressure down to a more realistic level. Ok rant off.
    Well said!
    Not just the spindle air blast, but there seems to be too much requirement for air and too much tolerance for air leaks.

    I'm sure I'll catch flack for saying that my shop is in my garage at home. As such, I want things to be as quiet as possible so the kids can sleep and also to be a good neighbor, ... besides just wanting things to be as quiet as possible for my own hearing and sanity.
    I don't want to have a compressor banging away all the time and late at night.

    I have a 60 gallon reserve air tank that I picked up, but I have a wimpy California Air Tools super quiet compressor, while I look for a much beefier, but hopefully still quiet compressor that I can actually afford. I like how quiet my compressor is, but it is definitely NOT able to keep up with my air leaks and with the demands from the VMC and CNC lathe.

    I want to get or build an air dryer system as well.

    Next up on my list is buying some BT40 tooling from you! :-)


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