Airsoft Gun Cylinder Repairs
Recently we have been asked many questions about how to trouble-shoot, repair and or upgrade broken airsoft gun cylinder parts, so here goes. I will begin our airsoft cylinder DIY repair tutorial with a quick overview of the cause and effects of these issues.
The typical modern airsoft gun gearbox is comprised of two parts, the mechanical system which includes things like the gears and motor and transfer electrical energy into mechanical energy. This mechanical energy then transfers to the air system at the point the sector gear meets the piston. The air system then converts the mechanical energy into pneumatic energy that propels the bb out the barrel.
The air system portion of a gearbox is made up of several components, the cylinder sleeve( number 3 in photo), cylinder head (4), cylinder head o-rings (5), air nozzle (6), piston head (2), piston o-ring (5), and piston (1). The bottom portion of this photo is airsoft gun parts from the air system we replace on a regular basis. I apologize for the stretched image but it does work.
So first lets take a look at the pistons referenced number 1, at the bottom of our repair guide photo shown here. As you can see the piston in any airsoft gun, works hard and typically takes a beating, especially in upgraded guns. The pistons in this photo show stripped teeth, and broken rims which are very common.This problem is typically caused by dirt build up in and around the piston, but can also be caused by over upgrading and gear failure. What about metal airsoft gun pistons?(link shows common metal piston wear) metal is good, but high maintenance, Let me explain; as a metal piston wears, it leaves metal filings (chips) in the gearbox that accelerate wear on the other parts of the gearbox. Without frequent (monthly) maintenance on your gearbox to remove the abrasive paste this leaves behind as it mixes with cylinder oil and gearbox grease, it will quickly become a major issue for the rubber orings and other moving parts. Do not get me wrong here, metal pistons are a great upgrade, they just come with some extra airsoft gun maintenance considerations.
I think the important part to point out here is that the piston is to the gearbox, what the tires are to your car. Because of the wear a piston faces you can just plan on replacing it every year or two depending on how much BB "mileage" you put on your airsoft guns.
Number 5, is the piston O-ring. I will just say, it also, is one of the items in the cylinder air system that will have to be maintained regularly. Keeping your airsoft gun properly oiled, with the right airsoft gun silicone oil will extend the life of the o-ring, but it should be replaced annually. If your gun shoots several or more bb's just fine and then sputters out a few more before shooting at the correct FPS, then your o-ring is probably failing.
Piston heads (2) in photo, can vibrate loose and cause damage. I will point out that a good upgrade piston head is shown here and features the anti shock bearing plus an embedded metal thread insert to avoid vibration damage.
The cylinder sleeve itself (number 3 above) is a common point of failure. If sand, dirt or fine metal chips get caught up between the piston head and the piston wall it will cause air system failure as described above. These particles can scratch the cylinder walls creating air leaks in the compression cycle. The chips can cut micro slices in the rubber o-ring causing even more air leakage. These can be hard problems to trouble-shoot, find and repair for a novice airsmith.
Next up is the cylinder head (number 4). I will include information about the air nozzle (6) here as well. The airsoft gun cylinder head caps off the end of the cylinder and forces all the air trapped by the "piston stroke cycle" to compress, while being forced out the air nozzle guide. The air nozzle guide is either machined or molded into the cylinder head body. This guide allows the air nozzle to slide back and forth on the guide a bb in the hop chamber and pass the compressed air down the barrel Stock guns, typically have the PVC (plastic) version installed. The brass guide that is molded into the PVC is a common point of catastrophic failure in airsoft guns so we typically recommend to customers to replace with a double o-ring full metal model like the one shown at the top left above.
Here is a quick maintenance and trouble-shooting tip I will pass on for the Do It Yourself crowd. Once you have the gearbox apart, clean, lube and re-assemble the air cylinder outside the gearbox. Place one finger over the air nozzle and gently shove piston down cylinder sleeve, a well tuned system will air lock, whilst a faulty system will leak air. This is a fast way to track down the part that needs to be repaired. Be sure and check the air nozzle guide first, then add the air nozzle and check again.
Best preventative maintenance plan? In our humble opinion, get a complete custom airsoft gun cylinder upgrade kit, the first time the cylinder side of your gearbox needs repairs. The one shown in green above in the pictures features a double oring seal, 1 piece machined metal cylinder head, polished metal black chrome cylinder, high impact ported silicone piston head with metal insert and thrust bearing, oring seal air nozzle plus a super high impact reinforced piston body. Buying these parts in a full kit assures high grade performance.
Well, I hope this has helped you understand the air cylinder operation of your airsoft guns. Basically you can plan on repairing at least one of these parts each year. With upgraded guns shooting at rates as high as 15 bb's per second on full automatic firing mode, the "moving parts" listed above will be cycling at 850-900 cycles a minute so heavy trigger time means more wear and tear.
Happy 2013! Airsoft gun service team.
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