Why Pneumatic Nail Guns Need Oil

This isn’t an all-encompassing course in nail gun repair, but if you’re experiencing a faulty nail gun, read this before tossing yours out the nearest window. There are several early warning signs that a nail gun is heading down the path to becoming scrap metal. The more common ones are firing only air, the trigger jamming, double or triple firing, and air leaking.

One of the Most Important Things many Beginners Fail to Do!

The first thing to remember – or know – is that most pneumatic nail guns need oil applied on a regular basis to function properly. As far as the machine is concerned you should apply a few drops before or after every nailing session, but this Angle view of finishing nail gunmay result in excess oil leaking out onto the work piece or your hands – which can leave stains as well as grubby oily fingers – just plain messy.

So for those of you who don’t use nail guns all too often, instead of applying oil religiously every nail-gunning session, you could opt to apply it on a per strip basis – which may translate into once every few sessions. You simply apply the oil after a nail strip has run out and before inserting the next one. Depending on the kind of nail gun you use the number of nails per strip may vary significantly. But I think you get the picture.

However, carpenters who use pneumatic nail guns for long hours, daily, often have more rigorous standards for oiling. It is often policy for nail guns to be oiled as much as twice a day! This is because these nail guns are subject to considerably longer and more intensive cycles and as such, require more lubrication. So bottom line, you should oil your nail gun in proportion to use.

“I still don’t get Exactly Why Nail Guns need Oil…”

As with any machine that has moving parts, proper lubrication is vital to ensuring a maximum lifespan. Lubrication helps to significantly delay the eventual loaded nail gun from topwear of the various moving parts. Without it, not only will parts wear prematurely, but parts may also stop working properly. This is basic for almost any machine out there.

For example, pneumatic brad or finishing nail guns have a piston that when under the force of compressed air, hammers the top nail – separating it from the remainder of the strip – and ejects it out of the chamber and into the work piece. But without proper lubrication, the piston can tend to get stuck and not want to retract back to its original position.

This is a problem as the remaining strip of nails are spring loaded and will try to move up and fill the spot where the nail that was just fired was. But the “hammer” attached to the piston hasn’t retracted fully and is therefore in the way of the incoming nails. This then causes any subsequent attempts to fire only air (dry fire) as the nail strip wasn’t able to properly align itself.

Why Old or Damaged Nail Gun O-Rings Might Cause Problems

There are other potential causes for the piston/plunger not retracting fully such as old O-rings. O-rings are used as a gasket to seal joints where air would otherwise leak out. Compressed air is not only used to drive the piston forward to hammer the nail out, but it’s also used to retract the piston back to its original position so the spring-loaded nail strip can move up.

The piston, powered by the compressed air, slides back and forth in a cylinder and is typically sealed with an O-ring to preserve the air pressure. But if the brown tipped finish nailsO-ring is damaged and leaking, the compressed air won’t have the necessary force to push the piston back to its original position. This is a fairly common cause of a nail gun “dry firing”.

A lack of lubrication can also cause excessive amounts of friction between the O-ring and the cylinder wall, causing an incomplete piston-retraction. This problem of the piston being unable to retract fully (but still retracting to a certain point) explains why a given nail gun may have no problem firing shorter nails consecutively but dry-fires when attempting to fire longer ones.

Visit How Stuff Works for details on how pneumatic nail guns work along with a simple schematic for visual aid.

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