CNC Compressed Air Needs

      CNC owners discuss compressor, tank, and pipe setups for good performance. October 13, 2008

We recently installed a Busellato Jet Optima RT router. Our 3-1/2 hp single stage compressor is not up to the job. It will run the router but only without blower running to clean out the cuts. If we run the blower for more than 10 minutes or so, the system pressure drops to the point where the router shuts itself down. I am told we need 11cfm for this. How do I go about sizing a compressor for this? Is a rotary screw compressor required? If so, how large? What should I look for? I also need to figure out what type of dryer to use. What should I be looking for? We installed a cheap desiccant dryer for the router, but the desiccant needs to be changed weekly, and this is before the humidity has even hit us yet here in the mid-west. I have available to me for $500 a 1971 vintage 2 stage compressor, 3-1/2 hp, 80 gallon tank. Would this be sufficient?

Forum Responses
(CNC Forum)
From contributor A:
When I first got my CNC, I had air issues also. I was running a 5 hp 2 stage with an 80 gallon tank. It would run the CNC fine, but as soon as a blow gun was used it would shut down. I picked up a 15 hp with 120 gallon tank and that seemed to do the trick. My pump still cycles frequently though has no problem keeping up.

From contributor B:
A point of real concern is the storage capacity that you have. If you have a large area and lots of wide copper lines for storage it will make a big difference. I have a 10 HP Quincy and with lots of storage lines and I never have a problem. I also tried one of those cheap chemical dryers, and it didn't work either. I purchased a refrigeration dryer from Graingers and it gave me plenty of nice dry air. Another thing to remember is that if your air compressor is always cycling it will be really hot air, with a lot of moisture.

From the original questioner:
To contributor B: Which dryer did you get? There are about a half dozen lines, with a dozen or so models in each line. I couldn't figure out which would be best for us.

From contributor C:
I have a 7.5 hp champion 2 stage with 80 gallon tank and it runs my Jet 3006 and my Dynabrade hand sander just fine. My air dryer is a "Belair" that's rated larger then the compressor.

From contributor B:
Each dryer is rated for the cfm of your air compressor. You want to match the cfm with your horsepower. You will be amazed at how pure the air will be. So many people spend big dollars on equipment and go light on things such as this. If you ever have had to replace air cylinders you will love this.

From contributor D:
You might see about getting another tank and hook it up to the other one. Have your CNC on the last one in the line and put a check valve on the inlet. This should give you more CF to work with and the only air that can come out of the second tank will be for your CNC. The bigger the compressor you get, the less it will cycle. I think you want at least 8 hp and I would go with 15 hp. If you get a small one, heat might be a problem.

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