Does anybody file their depth gauges/rakers past the guide setting? The reason I ask is that I recently bought an ex pro saw which had the rakers way below the guide setting and it cuts really fast. I'm guessing from a safety point of view this may be a bit aggressive and tend to bite in.
Also wondering if some of you may reduce the rakers when milling to get a decent chip.
Regular raker guides are nearly all way too "wussy". To form proper chips instead of just dust, the angle between 1) the raker top, 2) the cutter tip and 3) the kerf should at least be maintained equal to that of new say 3/8 chain. This angle is ~5.7º but as the chain is sharpened, if conventional 0.025" raker gauges are used that angle becomes lower and lower and makes fewer chips and more dust.
If you don't want to measure angles then use a feeler gauge and a ruler across the cutter to measure raker depth and a set of callipers to measure the gullet width.
Stock 3/8 chain uses a 0.025" raker depth when the gullet is about 0.25" - that's a ratio of about 1:10. So when the gullet reaches 0.5" the raker depth should be 0.05"
Even if you were to maintain a 1:10 ratio for the life of a chain you should get similar to new chain performance during this time.
BUT
For optimum performance you should adjust the ratio/angle to suit you bar length, chain type, power, drive sprocket pin count, wood size , type, dryness etc.
In Aussie hardwood (in most cases harder than dry hickory) I use a 6.5º on an 880 with a 42" bar.
On my 441 with a 25" bar and Lopro chain (thinner kerf) I use 7.5º
Chain saw millers in the milling form have reported using up to 9.5º on a 36"? bar on a 660 in North American softwoods.
The way to determine the optimum raker dept is to: swipe the rakers 3/4 tmes - cut, repeat the previous unit the chain becomes too grabby.
Then file the cutter tips back until you feel comfortable about the grabbiness.
Then measure the raker angle.
Of course the optimum while; change so you need to fond a happy medium. I used to keep loops with different raker settings but its very hard to label chains so I make my main variable Sprocket pin count.
It was possible to purchase raker gauges of 0.005" increments ie 0.025, 0.030, 0.35, etc but have not seen many of these around.
My raker setting method uses a digital angle finder.
However, in the field I touch up the cutters after every tank of fuel and just swipe the raker 2-3 times every 3-4 tanks of fuel. Then check the settings back at my shop at the end of the day.
My chains cut equally as well during most of their lie times. Eventually the chain does not clear the chips/sawdust as well as a new one which is about when I replace the. Bu then 1-2 cutter tips may have even broken off.
Trade offs of using angles >5.7º (1:10 ratio) are increased chance of kickback, greater vibe, and wear and tear. In a CS milling situation kickback is not an issue.You just need to be aware of picking up a saw with a a chain with higher raker angles to use in cross cutting.
