Keep Your Air Sanders Running Smoothly

5 tips to keep your pneumatic sander running in top-performing shape, so you can get the best sanding results possible.

Even though sanding with a pneumatic random orbital sander may seem like a simple activity, challenges can arise - causing frustration, along with flaws in the workpiece. As with most aspects of woodworking, getting the best results in your work comes down to a combination of using proper techniques in the various applications and processes while properly maintaining your equipment. So, if you are experiencing issues with your pneumatic sander or with your sanding results - such as swirls or other visual defects, blotchy and uneven finish, inefficient removal rates, or otherwise - the tips in this article offer good guidance.

1. Check the Air Pressure

If you notice that your air sander is not performing consistently and perhaps, you're seeing swirls or other sanding marks repeatedly, the first thing to check is if your compressor is providing sufficient air pressure for your sander to reach the ideal rotations per minute (RPM - speed).

In general, AirCraft air sanders require 6,2 Bar (90 Psi) to run optimally, thus if you only have one machine attached to the compressor, simply check that you are set to 6 Bar and that the full 6 Bar is reaching the sander. While it is possible to run the sander on less than 6 Bar, the sander will not perform well and the results may not be ideal.

It becomes more complicated when multiple pneumatic tools or machines are running from the same compressor simultaneously. In such a case, it's possible that while the compressor may technically be putting out 6 Bar pressure, with other machines attached and turned on, all machines in operation would be sharing the air pressure output, meaning that each machine might not be reaching its required pressure levels. If multiple tools are in use simultaneously, make sure that your compressor is set to output enough pressure to meet the minimum requirements for each connected tool.

2. Check your Speed (RPM - Revolutions per Minute)

Random orbital sanders are designed to run at 12,000 RPM and 10,000 RPM for 75 x 100mm orbital sanders. While it is possible to achieve a good finish at 10,000 RPM, lower speeds will cause significant sanding marks. As sanders age, if not properly cared for, they will lose operating speed (RPMs). Most operators will not realize this is happening and will continue to use their sanders, only to find bad results escalate over the same time frame. Checking your sander's speed RPM is a simple way to maintain a consistent finish and keep the subpar workpieces to a minimum. A Vibrating Reed Tachometer can be used to check the speed. If it is not spinning at the proper speed RPM, try oiling the sander and testing again.

3. Do not remove the filter cap on the back of the pneumatic sander

When looking at your pneumatic sander, you may have noticed the two cylindrical ports on the rear - one where one connects the airline from the compressor, and the other has a grated cover. This cover is a filter cap that covers a nylon filter. The filter cap plays an important role in the proper functioning of the sander: keeping the inside of the sander clean from all the particles and debris created from sanding.

While it may be tempting to remove the filter cap under some circumstances, this is a bad idea and is never advised.

As one operates the sander, the air is forced through the sander causing the moving parts to spin, which creates heat and liquefies the grease in the bearings. When the lever is depressed, we drive the air through the sander, however, when we release the lever, this opening becomes a vacuum, allowing any debris to enter the sander motor and bearings. As the bearing grease hardens, the debris becomes like sand, and the wearing on the bearings is unrepairable. Once the bearings are not free to move, the bearing will lock up and the bearings will require replacement.

4. Oil the sander regularly

When you start noticing the sander is not spinning well, what is required? Probably one would naturally try to compensate by pressing harder. In such a scenario, the sander becomes useless and you might as well be sanding manually.

The fix for this is to make sure to oil your hand sanders daily. This keeps the housing and bearings lubricated and moving freely. As we sand, we create heat, which causes friction. This friction is not a friend to the sander, as it will dry out the phenolic vanes to a point they get dis-lodged in the housing, stopping the motor from turning.

If you use your pneumatic sander regularly, the best way to keep it operating well is to keep it lubricated using a pneumatic oiler in the line. If you do not have a pneumatic oiler, simply put about 2 drops of machine oil in the air intake area at the end of the day and run the sander briefly to spread it around. This regular practice will keep your sander lubricated and prevent it from locking up.

5. Keep backup pads fresh and maintained

Often ignored or actively avoided area of maintenance on orbital sanders is the backup pad. While replacing them is easy, it can often go overlooked when trying to save money or otherwise conserve tools. When your backup pad is bad and left unchanged, you will notice the results in the finish.

Firstly, to lengthen the life of your backup pads, practice proper sanding techniques and routinely clean your backup pads well.

With vinyl face pads for PSA (sticky) back discs and sheets, make sure to clear the adhesive residue each time, and clean it properly. While cleaning will help, any residue left on the pad will cause an uneven sanding surface, meaning, the next sheet/disc will conform to the unevenness underneath – leading to sanding result issues. In addition, take note of other signs of damage on your pads, such as torn edges.

When it comes to loop and hook face pads, excessive heat and overuse can cause the hooks to straighten out. When this occurs, your discs/sheets will no longer stay properly attached. The only solution for this is to change the backup pad.

Although time will vary between changing backup pads, the best is to keep them well maintained. Make sure to keep an eye out for the signs and do not be shy about replacing them.