Thanks. So, square filed as opposed to round filed chisel chain will be 10-15% faster. Which of those two will hold the sharpness longer when there might be a wee bit, not heaps, of dirt about? I've struck upon some grinding angles (round grinder) for full chisel that seem to hold up well enough and cut at good speeds in the wood I come across. It's made me wonder if I should be coveting a Simington square grinder as much as I used to. I've read some guys say they can tweak the square grind angles to help the edge hold in hard or dirty wood and they still prefer that grind over round ground. I am keen to compare the experiences of those who use the two options for Stihl chisel chain - square and round grinding.
Either that or find someone with a Simington and buy a stihl chisel chain off 'em and compare to my round ground stihl chisel chain to see if I still want a Simington grinder.
Clear as mud?
I believe square files holds an edge just as well as round file, and neither square or full chisel round will cut w/o a good corner. Semi chisel is more durable in dirt, but so slow I would rather re sharpen.
I rarely take a chain off of a saw, and sharpen by hand, so I prefer square. If you use a machine and like round, than be happy. Machines that will do square are generally very expensive.
Round and square can both cut well. The advantage of square is it matches the angles of the tooth. The angle for round perpetually changes. The corner is always most important, after that the side cutter, as it cuts the grains of wood (the top plate is just a chisel to remove chips). With round, the angle of the side plate is an arch, not a straight line.