Stihl Chain Markings?

[jteneyck]

I have used Husky's and a Shindaiwa for many years, but just bought my first Stihl saw, an MS-290.  Yeah, I know, not a pro saw, but I expect it will serve me well for cutting firewood.  Anyway, the saw has an 18" bar with 26 RMC3 chain on it, a 0.325 pitch, 0.063 gage chain.  On the top of each tooth is a mark at 30 deg, the same as the tooth grind angle.  These I have seen on many chains.  On the outside of each tooth is a curved mark, the top of which would probably intersect the mark on the top of the tooth.  The curve of this mark is not the same as the side plate grind.  What is the meaning of this mark?  Could it be "Use a round file."?  And maybe indicative of the file diameter?

Look forward to learning what these marks mean.  Thanks. 

[Rocky_J]

The mark is the furthest they recommend you file the chain before discarding it. At that point the tooth is too small and you risk snapping it off.

[jteneyck]

Thanks, Rocky.  I've always replaced chains way before they got that short.  Guess I've been throwing them out too early.  Do you think they still cut well as they get this short, assuming they have been properly sharpened and the depth gages maintained correctly?  Thanks, again.

[Rocky_J]

Yes, I use my chains until they are worn out. Although getting seriously rocked out on a well used chain may make it not worthy of rejuvenation. Because the tooth gets narrower as it gets shorter, you have to get a bit more aggressive on the rakers on the last bit of tooth. Towards the end I'll even file the rakers from the side a bit, to make them narrower. That's usually only on the last 10%-20% of tooth though.