Duo Fast CN 350 misfires

[bad_idea]

I have a Duo Fast CN 350 framing nailer I bought used for $12.50. I am building a shed now and this thing is giving me hell. I was having trouble w/ it not reseting after firing a nail, I had to disconnect the air for it to reset to fire the next nail. I then bought an o-ring kit on ebay and replaced the o-rings and the upper cylinder seal. I then had problems w/ it hissing air out the top of the gun and not firing nails. So I took the top cover off and fidgeted w/ the assembly up there and it started working good. But now it misfires at least 50% of the time. I am unsure what the issue is. I didn't really look into it yet due to it ******* my off so much. I really want this dumb thing to work so I can build this shed. Any ideas?

 

[widdors]

I've worked on this tool quite often, and when the tool skips it's almost always the blade seal. To get to it you'll have to remove the track, its held on by the bolt and bushing on the safety, the bolt at the bottom of the handle, and the pusher assembly. Once the track is out of the way you can see a set screw on the bottom of the nose. It works best to take the piston assembly out and push the driver blade in through the front of the nose, then you need to adjust the set screw so that the driver can slide back and forth in the nose, but just barely wiggle side to side. Definitely use some loctite on that set screw.

 

[bad_idea]

Thank you for the info. I didn't look at that part of the gun when I replaced the o-rings. I'll take it apart today after work. Is there anything else I should look at while I have it apart? Thanks again.

 

[widdors]

As long as the pusher spring is in good shape without any kinks or bends, you should be good on that end of the tool. While the cap is off, double check that the exhaust valve is okay. That is the white plastic piece in the cap. Sometimes they will crack, or the bolt will strip threads, and there will be play in the head valve which will cause leaks or misfires. With new o-rings, an adjusted blade seal, and a good exhaust valve, that mailer seems to run forever.

 

[bad_idea]

It was that set screw. Dab of lok-tite and snug the screw up, worked great. I would have never figured out that was the issue. Thanks a lot for the help. It appears you joined the forum just to answer my question?

 

[widdors]

You're welcome. I was researching a couple of different tools and ran across your question. This is a real friendly and helpful place, and I've found info I needed, so I joined to help out. I'll probably stick around a while and maybe pipe up here and there.

 

[bad_idea]

It's a great forum w/ a lot of information. Most of the people just want to help out. There are a few safety nazi's though, some questions get them fired up in a hurry. Don't even whisper PVC air line around here.