Pulled this from another site:Smooth Lumber at slightly lower speed:
To produce smooth lumber with sawdust extremely fine ( it will blow away in the wind ) you must use a full house standard chain ( the most teeth ). You can purchase standard crosscut chain with the teeth at 35 degree angle or oregon rip chain with the teeth at a 10 degree angle and modify it to produce the smoothest lumber. To modify the above chain you choose a tooth and file it to 0 degrees ( straight across ) and only take off enough to get the tooth angle changed to 0 degrees. Measure the length of this modified tooth with calipers or adjustable wrench, then file all the teeth to the 0 dgree angle and the same length. you measure the tooth and file the rest to the same length so that all the teeth are the at the same height. If you look at a tooth from the side you will see that it is angled up towards the cutting edge, so as you file the tooth and it gets shorter, it also gets lower. If any of the teeth are longer than the others, therefore higher, only these teeth would be doing most of the cutting. This would create a judder and vibration in the saw and a much slower cutting speed. This is not as hard as it sounds, just get all the teeth the same length and all at 0 degrees or straight across.
I bought some ripping chain and it was set up differently, with some of the top plates removed and cutters at 5° and 20°.
I am new at this stuff and can't tell you what works best.
Also, Oregon Chain has a lot of info on their site and I think Stihl might as well.
