Air Compressor Tips

My Studio Air Compressor: Coleman Powermate Industrial 5HP, 220-volt, 22 Amp, 60 HZ, 1-Phase, 2-Stage Aluminum Pump with Cast-Iron sleeve inserts, Kick-in 145 PSI, Kick-out 175 PSI, Max tank pressure – 200 PSI, ASME certified tank. Purchased new about 13 years ago for $750.00. This compressor delivers 18 CFM @100 PSI, 16 CFM @ 175 PSI.

My compressor.

Overview: One of the most important pieces of machinery in my studio is my air compressor. For me, the thought of turning without an compressor is comparable to the thought of felling a large tree with a dull hand axe. I’ll use a chainsaw every time… In my studio, an air compressor is a true workhorse and is one of the most frequently used pieces of machinery I own, next to my Oneway 2436 lathe.

Pneumatic Tools

These days I use a few electric tools, but most of my work is done with various pneumatic tools including drills, sanders, airbrushes, HVLP and conventional spray guns, a pressure pot and more. For sanding, pneumatics drills make the abrasive protocol much easier. They run cool as a cucumber no matter how long you use them and usually cost less than comparable electric drills that are typically used for sanding woodturnings.

Pneumatics also have a very long life expectancy… I still have the first 3/8" pneumatic drill I bought to power sand my production bowls more than thirteen years ago. During that time, it has seen brutally heavy use and it has never required a single repair! The best electric drill I owned (cost new $250.00) only lasted six months, even with blowing the motor out every single day.

Although my needs for a reliable power sanding solution were in large part responsible for my move into pneumatics, I use my air compressor for many odd jobs around the studio. Once you have compressed air available, you will find new ways to use it for hundreds of jobs. If you already have an air compressor, congratulations… I have some maintenance tips that will help to keep your air compressor in good working order. If you do not have a compressor as yet but are thinking about getting one, I have a few tips that will help you to narrow your choices down to a unit that will serve you well in your studio.

Air Compressor Buying Tips

Note: Always consult a qualified electrician for any wiring questions you may have regarding installation or code requirements, or to install new electrical service wiring. If you’re thinking about buying an air compressor to use in your studio, here are a few tips to consider before you dust off the plastic:

  • Size Matters: You can always use a large air compressor for running small tools, but you can rarely use a small compressor for running large tools. If you choose a compressor unit that is too small, it will run too frequently (gobbling lots of electricity in the process) and it will not be able to keep up with your demands.When your air compressor is unable to meet demand, the air pressure will drop, which may cause your tool to stop functioning correctly. My best advice here is to determine what your tools will require and then purchase one size larger than you need. This will allow you some room to grow and a bit of reserve capacity for future tools that may need more CFM to operate properly.
  • Electrical Supply: My air compressor is set up for 220-volt electrical operation. If your studio does not have 220-volt service, you have two options - 1.) Get an electrician to wire a dedicated 220-volt service line for your studio, or 2.) Look for the best 110-volt air compressor you can find and use it within its limitations. Remember though, that a 110-volt line will only operate compressors up to three horsepower maximum. If you need a larger air compressor, you’ll have to get your wiring updated.

  • Cubic Feet Per Minute (CFM): CFM is the amount of airflow the compressor is capable of producing. Check all of the tools you plan to use for the CFM requirements and plan accordingly when buying your air compressor. It’s usually best to buy the tools you will be using first and then purchase the compressor that will handle those tools, rather than doing it the other way around. Also remember to leave yourself some wiggle room for future tools you may purchase and any supplemental requirements that may develop like automotive tools, larger sanders etc.

  • Pressure (PSI): Pounds per square inch is a measure of the compressors capacity to compress the intake air to a higher pressure. Each tool you purchase will have specific requirements for the PSI and CFM it needs to operate. Your air compressor must be able to produce these amounts or the tool will not operate correctly.Single stage compressors usually are rated to a maximum of 125 PSI, whereas two-stage compressors are rated to 175-200 PSI. Once again, the tools will determine what type and size of compressor you will need. Note: Most air tools require 90 – 100 PSI to operate.
  • Horsepower (HP): More horsepower = more CFM in most cases. These days, it can be difficult to determine the actual horsepower of some motors due to the fuzzy way some manufacturers do their horsepower “math.” My advice here is to stick with well-known manufacturers that list all of the data necessary for determining the proper horsepower of the compressor.Based upon my experience, a five horsepower air compressor with a 60-gallon reserve tank is the minimum I would consider if you want to use your compressor for power sanding. Sanders can be real air hogs, so check your tool requirements and purchase accordingly. When it comes time to replace my compressor, I’m going to get a slightly larger unit (probably 7.5 HP) and a 100% cast iron 2-stage pump assembly, just in case I need the extra capacity.
  • Pump Type: Most compressors are built with aluminum or cast iron pump assemblies. Cast iron is the best material by far, but it’s also expensive. You find cast iron pumps on better quality compressors, most two-stage models and on large industrial duty pumps. Cast iron is more expensive than aluminum and lasts a lot longer. Aluminum is typically found on lower cost compressors, but may serve your needs well enough.When I purchased my compressor, I was busy buying lots of other tools and equipment and I decided to forgo a 100% cast iron pump model to save a few bucks. Luckily, my compressor has cast-iron sleeve inserts and has served me well! If you plan on using your compressor a lot, get a 100% cast iron model or if cost is a factor, look for an aluminum pump with cast iron sleeves.
  • Reserve Capacity: Size matters here as well… Reserve tanks are the reservoir where the pressurized air is stored until it’s used. In the U.S., reserve air tanks are measured in terms of liquid gallons, for example 30-gallon, 60-gallon, 80-gallon etc. The larger the air reserve tank, the more pressurized air is available for you to use until the compressor has to kick in (initiated by a drop in the reserve tank pressure) to begin recharging the reserve tank. The smaller the tank, the less air you will have in reserve and the more your compressor will have to run to keep up with you demand as the reserve drains down.Better quality tanks in the U.S. carry an ASME (American Society of Mechanical Engineers) approval stamp. ASME tanks are built using very strict manufacturing standards, something you really want when you have a large tank of pressurized air nearby. Be wary of models that do not carry ASME certified tanks. My compressor features an 80-gallon reserve tank, which is adequate for my production sanding and most other uses.

Air Compressor Maintenance Tips

No matter what type and size of air compressor you have, you need to keep it well maintained so it’s always ready when you need it. Most compressors work so well that it ‘s easy to forget about maintenance, especially if your unit is located in an adjacent room, or outside. Out of sight = out of mind… Although air compressors do not require much in the way of maintenance, the maintenance that’s needed is critical to insure your compressor keeps working correctly. The tips below assume you’re working with an electric compressor with an oil-bathed pump that’s installed inside the studio.

  • Read the Manual: Always read and follow any maintenance and safety requirements by the manufacturer for your compressor. Most manufacturers can supply a copy of the owner’s manual if you have lost yours, or if you bought one that did not have a manual. Check the Internet website of the manufacturer to request a copy of the owner's manual.

  • Drain the Tank: The owner’s manual will give you the recommended interval for draining the accumulated moisture from your tank. Most compressors have manual drain valves that are located on, or near the bottom of the tank. I always drain my tank at the end of every day that I use the compressor. On days where the use is very high, I will drain the tank several times as necessary. Accumulated water is not good for your compressor tank and it can cause all kinds of problems with your unit, so drain the water regularly.

The oil sight glass is visible
near the bottom of the pump housing.

  • Check the Oil Level Regularly: My compressor features a clear sight window that indicates the oil level, so it’s easy to double check if there is enough oil in the pump. Make sure you check your oil level regularly, especially if the unit is installed in a room you do not use frequently, or if it’s outside. If you unit does not have a sight window, check the oil level dipstick. Low oil level is a killer for compressor pumps, as a couple of my friends found out. You also need to change the oil as the manufacturer recommends to keep the pump properly lubricated. For those of you who have a compressor now, can you remember the last time you replaced the oil? Oops!
    The large moisture separator (left) features a
    drain valve on the bottom that allows easy
    removal of accumulated moisture.

  • Drain the Moisture Separator: Since we are so humid where I live, I installed a moisture separator in the line coming from the compressor. This helps to remove moisture from the air before it reaches my tool. I say helps, because it does not remove all of the moisture, but it sure does help.This separator can fill with water and should be emptied as necessary through the drain value that is located on the lower part of the housing. If I’m shooting a finish with my HVLP gun or airbrush, I always install a disposable desiccant cartridge in the line to remove any residual moisture in the air. These disposable desiccants can be purchased at most paint/hardware stores.

Additional Tips

  • Location, Location: Most reciprocating air compressors are air-cooled and require adequate ventilation (and space) around the compressor to operate correctly and to prevent premature wear on the pump. If you install your compressor inside your studio, make sure you install it in an area that offers sufficient cross-flow ventilation, so the motor does not overheat. Exterior installations may require special electrical wiring and sound proofing, depending on the area and any local noise ordinances. Protection against freezing may also be needed, depending on the area.

  • Noise: Even smaller air compressors can make quite a bit of noise when the compressor is running. I always wear hearing protectors when I’m sanding or using the compressor. It’s been a habit of mine ever since I opened my studio. My new 3M PAPR respirator features built in hearing protectors that make it easy to insure that my hearing is protected. If your compressor is in the same room you work in, or close enough that the noise is too loud, get yourself some hearing protectors. Don’t risk damaging your hearing, remember you’ve only got two ears!

  • Pancake Type Compressors: Many woodturners have small pancake type compressors in their studios for use with traditional woodworking, or carpentry. These smaller compressors are great for running pneumatic nailers and similar tools, but they will not run pneumatic drills or dual action sanders for sanding on the lathe. If you want to power sand efficiently on the lathe, you’ll need a larger compressor. Good luck and happy sanding!

Safety Note: Always follow all manufacturers safety instructions before working with your lathe, or any of the tools or products you may use. If you are unsure about any operation, obtain competent professional instruction before proceeding. Use and wear all necessary safety devices during turning and observe safe woodturning practices to prevent accident or injury.

Steven D. Russell is a professional studio woodturner, teacher and writer. He has written numerous articles for international woodturning magazines, which have been published in more than 78 countries around the world. Steve has demonstrated in numerous cities across the United States. His studio, Eurowood Werks, specializes in bowls, platters and hollow forms with unique visual and tactile treatments.

Steve is also a regular featured writer for the Guild of Master Craftsman's "Woodturning" magazine, published in London England. Woodturning magazine is the world's leading magazine for woodturners. Look for his monthly articles covering technical topics, or project based articles in each issue.