How to Sand a Car With an Air Sander
Air sanders, sometimes called dual-action (DA) sanders, are one of the most useful tools for the body-repair mechanic or the ambitious amateur repairperson. Run by compressed air from a tank, air sanders come in a variety of shapes and sizes, usually with a 90-degree angled head and a sanding disk pad surface that is six inches in diameter. Some models use catch bags for sanding dust. The best air sanders have variable speed controls for regulating the sanding speed of the disk. Simple to operate, the air sander does require a few special techniques and safety precautions before use.
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Things You'll Need
- Air sander
- Sanding pads
- Clean towels
- Acetone
- Masking tape
- Particle mask
Instructions
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Examine your compressor tank and the hose fittings that accompany it. The connector hose from the air sander should have a male or female fitting that matches up with the tank fitting. Connect it, and make sure the connector snaps together joining the two hose ends. Turn the compressor on, and monitor the compressor tank gauge. You'll need a full tank charge to run the air sander, so let the compressor fill the pressure tank until it reaches the maximum level.
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Select the proper sanding head for the air sander disk. Various grits have been designed for coarse, medium and fine cutting. Start with a heavy grit pad, either the stick-on variety or the bolt-on variety, and attach it to the air sander's circular flex wheel. Grip the bottom part of the sander with one hand while holding the leverage handle with the other. Trigger the motor. You can regulate the rotation speed of the sanding head by depressing the trigger in or out.. A medium speed works well for all applications. Practice raising and lowering the rpm of the air sander until you gain confidence with the feel and are used to the noise.
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Choose the sanding disk. Start with a coarse, 220-grit sanding head. To remove heavy rust, chalk off the area you want to sand, leaving a few inches of extra margin. Turn the air sander on, and position your arms so they extend horizontally, with the air sander hose at the bottom toward your knees. Lean slightly forward and push the air sander head into the body panel, making light contact. Sweep the sander slowly back and forth over the rusted area, starting at the top and working down. Do not lean your body weight against the sander -- it will do the work for you.
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Sand the rusty panel nearly to the base metal, but make sure you do not penetrate the panel by applying too much pressure. Turn the air sander off and change the sanding head type. Try a 400 grit for medium sanding. Turn the air sander on and continue sweeping back and forth, removing more rust. If the finish looks smooth and appears rust free, you can stop at this point. Use acetone to wipe the area clean. This type of surface will now be ready for bonding putty and paint work.
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Prepare the car panel to be painted with a putty patch (for example, Bondo). Chalk off or run masking tape around the area to be sanded. Start with a coarse sanding head. Turn the air sander on and push the sander against the panel, using just a bit of body weight. Use smooth, even back-and-forth strokes from one end of the patch area to the other. Take off a considerable height of the putty. Change the sanding head to a medium sanding disk and perform the same motions. Change out the sanding disk one last time for a fine, 600-grit pad. Finish sanding all the way down to the base metal with the fine sanding head. Wipe with acetone. This last fine sanding will prepare the panel for priming and painting.
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Tips & Warnings
Practice moving the sanding head across the metal surface as though it were gliding easily and smoothly. Do do bend the sanding flex head into the surface -- the edges will groove the metal. Always keep the sanding head parallel to the metal surface.
Change out sanding heads frequently. Don't let them pack up with residue.
Always know the location of your air sander compressor hose. Hold the sander so as to keep the head of the sander higher than the hose. Never flip the sander 180 degrees. A hose that gets caught and wrapped in the shaft can cause serious injury.
Use a particle mask if the air sander is not equipped with a dust catcher.
References
Resources
- Photo Credit workers image by petar Ishmeriev from Fotolia.com
