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Air Compressor Size Recommendation

Tom Albrecht

Tom Albrecht

Joined
Feb 8, 2014
Messages
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Location
Evanston, IL USA
I have a 2 stage 5hp Quincy compressor and I am all set. But, I have a friend who wants to get into pneumatic sanding and is wondering about minimum compressor requirements. I tend to think that a 2 stage compressor is needed.
Thoughts?
 
Tom,
I would agree with you, it sounds like a 2-stage, 5-7 hp compressor with a 60-80 gallon tank. A good one will cost about $2000+. My goodness, why does your friend want pneumatic sanding? It is expensive, very noisy, and the tools require regular maintenance. Pneumatic sanding is typically used where high removal rates of material are required. Think auto body work, metal fabrication, etc. Yes, they can and do work well in wood working, but you can buy a lot of dependable, electric angle head sanders for the kind of money your friend is thinking about. I wonder what your friend is trying to accomplish.
Jon
 
John,
That's a good question. She is responding to my recommendation to consider pneumatic when she asked about power sanders, as there are a lot of turners, myself included, and many of the pros, that use the Grex sanders and other pneumatic grinders and chisels in their turnings. I did advise considering electric angle sanders as well. Additionally, my advice to her, as in my advice to anyone who is gearing up, was to get the best you can afford, because you will always have it if it is high quality, like the big Powermatic lathe she uses.
 
I have a "5 HP" two cylinder compressor from the big box store and multiple el cheapo Harbor Freight pneumatic right angle die grinders set us as 2" and 3" sanders. The compressor mostly keeps up with the die grinders. I don't run the grinders for extended periods. I suppose that if I were a production turner and doing nothing but sanding, I could run out of air for a few minutes, but as a hobby turner working on a single bowl I have never run out of air.
minutes
 
Having discovered the small Grex pneumatic ROS I'm seriously considering upgrading my compressor. I'd love to find a similar electric sander, but AFAIK there is nothing even close. My current compressor, a single stage 80 gal from the Home Depot 25 years ago won't keep up with the sander. For now I sand for 2 min than wait 5.

The new generation of brushless motor electric sanders are wonderful, small and well balanced-- I have both a Festool and Mirka Deros, but they are too big and unwieldy for sanding inside bowls. My trusty Sioux angle drill is still going strong, but is not a ROS and leaves swirl marks when used off the lathe. The Arbortech ROS attachment for an angle grinder works well, but the noise and weight of an angle grinder is seriously tiresome plus the bulk of the grinder limits maneuverability. The little Grex pneumatic is just about perfect and a great justification for pneumatic sanders.
 
I have a Sioux pneumatic angle drill that I don't use. It would keep my 5 or 6 hp Cambell/Hausfeld compressor with a 50 gallon tank running non stop. The small random orbit sanders are good for grits 220 and above, so more for polishing. I didn't find them good for grits under 220, kind of like the micro mesh abrasives.

robo hippy
 
Roger Wiegand said:
Having discovered the small Grex pneumatic ROS I'm seriously considering upgrading my compressor. I'd love to find a similar electric sander, but AFAIK there is nothing even close. My current compressor, a single stage 80 gal from the Home Depot 25 years ago won't keep up with the sander. For now I sand for 2 min than wait 5.

The new generation of brushless motor electric sanders are wonderful, small and well balanced-- I have both a Festool and Mirka Deros, but they are too big and unwieldy for sanding inside bowls. My trusty Sioux angle drill is still going strong, but is not a ROS and leaves swirl marks when used off the lathe. The Arbortech ROS attachment for an angle grinder works well, but the noise and weight of an angle grinder is seriously tiresome plus the bulk of the grinder limits maneuverability. The little Grex pneumatic is just about perfect and a great justification for pneumatic sanders.
Click to expand...

Here's a good'n: https://www.aircompressorsdirect.co...UHMFjS4FLuitXxBA4aZtzUi8ZGlg6RpxoCyMAQAvD_BwE
 
I have a Grizzly 2.5hp I think on a 10 gallon tank with 5 gallon attached for effective 15 G. This compressor is over 20 years old and runs on 220. I use one of Ken Rizza's ROA air sanders and the compressor has not failed but does sometimes seem to run a good bit.
 
Does any one know about the California Compressors? They had one at the last Oregon Woodturning Symposium about 1 1/2 years ago. Very quiet. I seem to remember that they were a bit underpowered, but can't remember....

robo hippy
 
robo hippy said:
Does any one know about the California Compressors? They had one at the last Oregon Woodturning Symposium about 1 1/2 years ago. Very quiet. I seem to remember that they were a bit underpowered, but can't remember....

robo hippy
Click to expand...
I have a tiny California Compressor that I use for brad nailer, car tires, bicycle tires. A lot of their quiet is from running the compressor slower, but I love that little thing. But I'm no fan of an big air compressor grinding away in the corner for sanding. I use a cordless Bosch adjustable angle drill for sanding on the lathe, and an electric Bosch 5" random orbit sander and electric Metabo 3" random orbit for sanding off the lathe.
 
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I have a small (5 gal) California Air Tools compressor. I mainly use it for blowing off tools, cleaning out hollow forms, etc. I don't use air tools, so don't need a big compressor. It sits on the floor about 8 or 10' from where I stand at the lathe. Pretty quiet, as compressors go - I can still hear tools cutting and the shop radio when it kicks in.

Someone did an airbrushing demo at Rocky Mountain Symposium a few years ago. We normally put the pancake compressors outside the back doors of the demo rooms, and have to leave the doors cracked open for the hose. Even then, we usually charge them and turn them off during a demo because of the noise. This compressor was right up front next to the demonstrator's table, and it wasn't a problem. I bought mine the next week.
 
I had a CAT air compressor for several years. They make nice, quiet machines. I had to replace mine when I needed more CFM. Don’t forget what Richard said, you must size your air compressor to the required CFM of your tools. This will surprise many people. You may find that you need a much larger CFM machine than you originally thought.
 
Air powered sanders are "hungry" - but I have never found that the electric angle drills did as good job for sanding. I own a total of 6 different power tools for sanding on the lathe. The 2 that I use consistently are the random orbital air powered ones. 1 is a Grex 105 degree angle unit and the other is a PROs from Woodturner's Wonders. I use the latter far more than anything else due to it's design allowing me to reduce/regulate the air flow and moderate the speed of rotation and it is a "palm activated" design as opposed to a pistol-grip trigger type. I have less hand fatigue with this one.

Any air powered sander will consume a lot of air. I bought this compressor for a couple of reasons: https://www.lowes.com/pd/Kobalt-80-Gallon-Two-Stage-Electric-Vertical-Air-Compressor/1000528985
1. 175 Maximum PSI 15.6 CFM at 175 PSI Hopefully...this will be enough for anything I need...ever.
2. I bought the floor model, which had a missing muffler and switch-...had to argue a bit, but - the store manager chimed in and gave me 20% off....AND made the dept. mgr. go pull the muffler and switch off one in the back of the store....SO, under $1000 - out the door.
3. Bought the extended warranty. It's big, it's heavy....and I hope I never need it...but hey - insurance - right?
 
At work most of our process and instrument air compressors are 3-phase 4160V, dry air is critical on most applications and pressure drop on the distributed system can cause problems with various systems. We have several large rental air compressors and dryers running most of the time to keep up with growing demand as we add additional air compressors to the system as it grows. Yearly we do audits throughout the facilities to identify air leaks and make repairs to minimize air losses on the system. A typical process or instrument air compressor install can exceed a million dollars depending on the horsepower and CFM needed. Air is one of those unseen critical commodities that is oftentimes overlooked in the business world.
 
Tim Tucker said:
1. 175 Maximum PSI 15.6 CFM at 175 PSI Hopefully...this will be enough for anything I need...ever.
Click to expand...
The SCFM (Standard Cubic Feet per Minute) Stated in the specs Is
“Air Delivery SCFM @ 175PSI (CFM) 11.3
Duty cycle is not mentioned. This doesn’t mean that the compressor is not good.
Just pointing out creative marketing like old hp ratings.
 
Timothy White said:
The SCFM (Standard Cubic Feet per Minute) Stated in the specs Is
“Air Delivery SCFM @ 175PSI (CFM) 11.3
Duty cycle is not mentioned. This doesn’t mean that the compressor is not good.
Just pointing out creative marketing like old hp ratings.
Click to expand...


Yep...the problem with "statistics" ala - Samuel Clemons ( Mark Twain)
 
Jon Minerich said:
I had a CAT air compressor for several years. They make nice, quiet machines. I had to replace mine when I needed more CFM. Don’t forget what Richard said, you must size your air compressor to the required CFM of your tools. This will surprise many people. You may find that you need a much larger CFM machine than you originally thought.
Click to expand...
Oh man, my employer would hate you using that acronym. Caterpillar Inc guards the use of those 3 letters like money depended on it!
 
Here's, I'm sure a crapy, little supposedly ros air sander that comes with 1,2 and 3" pads. Claims it takes 4cfm @ 90psi. I think the key is if you are getting a compressor that is the bare minimum then the bigger the tank the better, otherwise it'll be compressing the whole time you use it.
I only post/mention this because it really is super cheap. And there was another similar one for $35. I didn't know they were so cheap. Make experimenting a bit more reasonable.
https://www.amazon.com/ZFE-Pneumati...r/dp/B07MT7PK82/ref=psdc_552888_t1_B085RP94DD
 
Raif - that sander would work better for the outside of bowls, much better than the inside. The length of it will limit many inside bowl curves. The hose connector will rub the wood I would think - bowl size and shape will dictate that of course,,,As well, I dont believe that one is a ROS...Random Orbital Sander. That is not absolutely necessary - but I find the ROS type of sanders do a better job of removing swirls/scratches
 
Raif Harik said:
Here's, I'm sure a crapy, little supposedly ros air sander that comes with 1,2 and 3" pads. Claims it takes 4cfm @ 90psi. I think the key is if you are getting a compressor that is the bare minimum then the bigger the tank the better, otherwise it'll be compressing the whole time you use it.
I only post/mention this because it really is super cheap. And there was another similar one for $35. I didn't know they were so cheap. Make experimenting a bit more reasonable.
https://www.amazon.com/ZFE-Pneumati...r/dp/B07MT7PK82/ref=psdc_552888_t1_B085RP94DD
Click to expand...

The specs say that it runs at fifteen thousand RPM! That is way too fast for sanding wood or just about anything else. Also, small high-speed air tools have barely any torque ... which is probably a good thing because it would stall out if sanding with coarse grit before it sanded a hole in your bowl. And, sanding at that speed with fine grit in my opinion would undoubtedly leave burn marks on the wood.
 
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