In the last post, we saw that it, perhaps, wasn't all that obvious how Stihl derive their model numbers - which you need to understand to be able to read a Stihl filing table. Last time, we saw that the first character of the model designator was based on the pitch of the chain. But what about the second character?
To decipher the model number we also need to recognise that the second number relates to the gauge of the chain. Just as there are industry standard sizes for chain pitch, there are recognised sizes for chain (and bar) gauge.
Starting from the narrowest, these are 1.1mm, 1.3mm, 1.5mm, 1.6mm and 2.0mm. Here, Stihl just take the number after the decimal point and stamp that on to the drivelink, thereby indicating the gauge of the chain. Therefore, a chain with a "3" stamped on to the drivelink is a 1.3mm gauge chain. Easy.
The second character of the Stihl model number is just this single gauge reference number. This means then, that with the knowledge gained from the last post and this one, if we have a chain stamped with a "2" on the depth gauge, and a "6" on the drivelink, then we can deduce that it's a 0.325" pitch chain with a gauge of 1.6mm; furthermore the model number (so far) is "26".
With the slightly older chains, the pitch was marked up differently, so a "3/8" on the depth gauge and a "6" on the drivelink would have told us that it was a model "36" chain.
We have now looked at how the model number is formed, but if you look at a filing table, you'll see a whole bunch of letters after this number - they gotta mean something. Surely? Well, yes, of course - and that's the subject of the next post.