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I started my woodworking career using a quarter-sheet electric sander, quickly graduated to a random orbit electrical disc sander and finally realized that I could significantly shorten sanding time with an atmosphere palm sander. I depended onto a 5" Dynabrade sander and Sears 3HP air compressor. It took me less than an hour to realize my mistake: The little compressor I bought could not begin to keep up air demands of the

industrial oil injected screw compressorsander. It would run out of air pressure almost immediately and the air sander would slow down to the point of being useless.

I did some math and discovered that I would need a ten horsepower air compressor with a large tank to do this. The big air compressor was so loud it could be heard all over the building and down the block but it powered those three sanders from dawn to dusk. The good news is that it paid for itself in saved sanding time very quickly.

Air sanders are aggressive and efficient. They are light in weight when compared to their lesser electric cousins. My sanders took to them immediately and production took off. I was as happy as they were. Soon there was another machine besides the air compressor required having large amounts of air in the shop: an Onsrud inverted pin router. It was also great to be able to blow sawdust of benches and machine while cleaning upon the shop at the end of the day. The compressor was also used to spray finishes on the completed furniture.

Years later, I built a smaller woodworking shop in my home which only required one air sander running at a time. For that shop, I purchased an air compressor half the size and isolated in a soundproof room in one corner of the shop. I ran 3/4" galvanized pipe under the store floor to three regulators at three different convenient places. The machine I purchased for that shop as a 5 HP Ingersoll Rand model with an 80 gallon tank. In the 80 PSI demanded by my Dynabrade sander, the compressor could produce enough atmosphere all day long. I have to say that that compressor has been very well built. All I needed to do was keep an eye on the oil level in the glass. At nighttime, I would switch off the master air valve on the side of the machine, leaving the electricity on, to silence the compressor to the evening.

I have to suppose that, having read this far, you have some interest in using a air compressor to power air tools in your store. Most likely, a 2-stage reciprocating air compressor will fill the needs of a small to moderate shop. As a rule of thumb, a 5 HP air compressor will power a single air compressor, a 7.5 HP machine will power a 10 HP machine will be necessary for 3 sanders.

The size of the compressor’s air tank is an important consideration: The smaller the tank, the more frequently the compressor will need to cycle on and off, This is hard on both the motor and compressor pump over time and it uses more power. I would not even look at an air compressor used to power an air compressor with less than a 60 gallon tank and I would feel much more comfortable with an 80 gallon tank.

The kind of electrical power required by an air compressor is another consideration. If you have three-phase power available at where you are, fine. Three phase motors have a tendency to use electricity a little more efficiently than single-phase motors. Substantial air compressors will all require 3-phase electricity but the 5 HP versions come either way. If you don’t have 3-phase power available, you are able to fabricate it with a rotary or electronic stage converter as I did in my smaller shop. Whether you utilize single or three phase electricity, you will need 230V AC power for single-phase motors and 208 or 220V AC for your three-phase selection. Make sure you check the voltage and amperage needs of any air compressor prior to buying it. Electricians can be costly.

A two-stage compressor pump is essential to get a machine of this size. Two-stage machines have two tanks, one bigger than another. Air is first introduced to the massive cylinder where it’s partially compressed and sent into the more compact cylinder for final compression to the tank. As air is compressed, heat is created and so a fantastic machine will have a finned intercooler built in.

Compression not only generates heat but squeezes water out of the air which winds up in the tank. Tanks can corrode over time and when this is not kept in check, the rusted air tank may eventually explode causing enormous damage and even death. That’s why it is critically important to drain the tank of water each single day. Most machines come equipped with a drain valve at the lowest point of this tank. If you do not want to spray water all over the ground under the compressor, you may choose to consider piping it in the valve into another location like under the floor or into a drain. Piped water will flow into a sink because it is being pushed from the tank by compressed air