Fixing a PC nailer

[chopnhack]

Has anyone rebuilt a PC BN138 brad nailer? I ask because the unit I have used for well over 5 years is now malfunctioning. Specifically the anvil is either getting stuck in the nail guide after firing (not retracting) or not firing. Either time you hear a wimpy sounding actuation of air. No hissing or leaking, just doesn't seem like the compression is taking place. The unit has been oiled regularly and has not been abused. The anvil does not look to be bent. The first place I found a rebuild kit seemed a little steep at 90% of a new unit's price! Any help would be appreciated. Thanks.

[LCHIEN]

o-ring blown out cut failed?

[chopnhack]

Not that I know of.... I took apart the back housing and pulled out the driver to inspect the cylinder to see if grit got in there and was causing drag, but no evidence of such. Everything was smooth and lubed up. The split ring around the driver's piston end looked in good shape. I reassembled the unit and still have no known leaks. The unit even worked for a time. I will have to disassemble it again tomorrow and break it down completely to look at each component. If I can pinpoint it to one item instead of buying the refurb kit, it would be time and money well spent!

[cabinetman]

Sometimes an "O" ring can be cracked or split without it being visible at a quick glance. Did you do removal for inspection?

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[Pappy]

I had an O ring go bad on my Paslode but it wasn't obvious to the eye. I would replace the O ring and try it before going the full rebuild route.

[chopnhack]

Makes good sense. When I reassembled the piston to the cylinder I did relube the split o-ring that seals the driver piston and the gun did work for a time. So the consensus is replace the driver piston o-ring and see if it works. Cheap and quick, thanks guys. I will see if they sell that part solo.

[LCHIEN]

piston or other parts can be cracked and not obvious as well. Esp. if plastic, as some are.

[chopnhack]

I err, the part number is bn125.. I took it apart and tried using some thicker lube around the oring underneath the split ring, it certainly spaced the split compression ring out more giving a tighter fit. I was pretty confident that it would work, but no go... I am thinking more and more that the problem lie elsewhere, but don't know if its worth troubleshooting. I may have to buy a new one.

On another note, if you don't have the correct length brads on hand, you can cut them to length with a cut off grinder, but they will not stay straight in the wood when fired.... go figure, the 18ga that were factory cut straight as an arrow, the 16g, very hard to keep straight

[LCHIEN]

Makes good sense. When I reassembled the piston to the cylinder I did relube the split o-ring that seals the driver piston and the gun did work for a time. So the consensus is replace the driver piston o-ring and see if it works. Cheap and quick, thanks guys. I will see if they sell that part solo.

you can take the existing O- ring down to a hardware store like ace, they have boxes of o-rings in the hardware section so you can pick one that's pretty close if not exact.

[LCHIEN]

Makes good sense. When I reassembled the piston to the cylinder I did relube the split o-ring that seals the driver piston and the gun did work for a time. So the consensus is replace the driver piston o-ring and see if it works. Cheap and quick, thanks guys. I will see if they sell that part solo.

you can take the existing O- ring down to a hardware store like ace, they have boxes of o-rings in the hardware section so you can pick one that's pretty close if not exact. They come in specific sizes (altho there's metric and imperial sizes, I think).

[cabinetman]

You might be ahead if you take the parts to the store and get one that fits the part.

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[cabinetman]

A used "O" ring will be sized differently than a new one for the same part. Matching a new one to an old one may not be the best method.

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[chopnhack]

Good points guys, thanks. The old o-ring did look undersized for the groove it was in. Specifically it wasn't wide enough any more. I was rather surprised that the grease trick didn't work... It formed a tight seal, so much so that I had to compress the split ring by hand to get it to go into the cylinder.

[LCHIEN]

Good points guys, thanks. The old o-ring did look undersized for the groove it was in. Specifically it wasn't wide enough any more. I was rather surprised that the grease trick didn't work... It formed a tight seal, so much so that I had to compress the split ring by hand to get it to go into the cylinder.

O-rings never fill up the groove horizontally. The plan is that the O-ring should be proud of the groove (vertical) and be compressed. When so compressed, it will get wider and then approach filling the groove horizontally. If it does fill the groove horizontally (Before compression) then there will be no more room for compression vertically.

Grease does not provide the seal, it should make the o-ring slide easier for assembly.

[cabinetman]

There's also the possibility that a non OEM "O" ring may have a different density factor. It may be softer/harder and not provide the correct seal, or allow the same movement.

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