Umbellularia
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Recently I bought my first loop of Stihl RSC full chisel chain. Previously I had only used Stihl RMC3 (and before that RM2) semi chisel chain on my 026 w/ 20" bar. I've recently been bucking up Douglas fir logs. At the rate my chain was getting used up, I'd have to buy a new loop one way or the other. The RMC3 had been really tiring me out. Thus I decided to try a more efficient chain.
The test:
Bucking a debarked 30" diameter 14'8" long log into 9 rounds. I started by making 8 bar-buried bucking cuts from one side of the log. The log was in the air for three of those - I could cut until the bar came out the bottom of the log. Another three had bark between the log and ground - I could cut "flat" until the wood chips changed color indicating I was cutting bark. For the last two, the log was slightly sunk into the ground - I had to finish the cut with the bar in a nose down position while feeling and watching for the difference between bark and sapwood. (In other words, I made eight cuts that were 20" wide and nominally 30" tall.) I then went to the other side of the log and finished the bucking cuts one at a time using the previous kerf to keep each cut aligned. Later, 5 of the rounds had to be noodled into half - I couldn't get them split with an axe or maul.
The observations:
Using the RS chain didn't tire me out as much as the RM chain did on previous logs. However, the ride was a lot bumpier. I think the bumps were the bar nose cutting the kerf deeper. I assume the RS cut faster ('cause I was less tired), but I didn't time it.
When lowering a moving chain into an existing kerf, the RS really wants to climb the sides of the kerf. I'll really have to be careful about that! (I've learned to insert the saw under slight throttle. If the chain is stopped, inevitably some sliver catches a tooth and the clutch can't get the chain moving.)
The RS seemed much more willing to cut to the side. I had to pay attention to keep from cutting circles. (If part of the bar is in an existing kerf, RM will dutifully stay lined up.)
The RS chain self fed much more eagerly than the RM chain. With the RM chain I could "hold it back", get a bit more engine rpm, and end up cutting faster. Not so with the RS. I also noticed no difference between 90% and 100% throttle.
Fuel usage was probably the same - lots: Two tanks for the bar-buried cuts, a third tank to finish bucking, and a fourth to make the five 16"x30" noodling cuts.
Bar oil use might have been less. This jibes with the lower engine rpm.
The RS didn't get dull any faster. The first sharpening was after the eight bar-buried cuts - right when I would have sharpened RM chain. This sharpening was easy! (In the past, the Stihl factory grind didn't match the specified files. It would take many, many swipes to reshape each tooth.) However, I did have to sharpen it 2 or 3 times to noodle one of the rounds. There was a really hard encapsulated limb stub in the round.
The wood chips on the ground were very similar. The chip lengths were the same. The RS produced wider chips and fewer narrow slivers.
And the biggest difference: Much less fine dust on the air filter! With RM I was having to stop every half tank of gas to clean dust dunes off the filter. (No, the RM was not dull.)
Conclusion:
I suspect that the safety vs non-safety chain aspect made little difference in this test. However, I now understand why there are no full chisel safety chains! For now, the RMC3 chain is back on the saw because I'm currently dicing up bark and cutting up small brush. I'm now open to the use of a variety of chain types.
(BTW, my first post here!)
The test:
Bucking a debarked 30" diameter 14'8" long log into 9 rounds. I started by making 8 bar-buried bucking cuts from one side of the log. The log was in the air for three of those - I could cut until the bar came out the bottom of the log. Another three had bark between the log and ground - I could cut "flat" until the wood chips changed color indicating I was cutting bark. For the last two, the log was slightly sunk into the ground - I had to finish the cut with the bar in a nose down position while feeling and watching for the difference between bark and sapwood. (In other words, I made eight cuts that were 20" wide and nominally 30" tall.) I then went to the other side of the log and finished the bucking cuts one at a time using the previous kerf to keep each cut aligned. Later, 5 of the rounds had to be noodled into half - I couldn't get them split with an axe or maul.
The observations:
Using the RS chain didn't tire me out as much as the RM chain did on previous logs. However, the ride was a lot bumpier. I think the bumps were the bar nose cutting the kerf deeper. I assume the RS cut faster ('cause I was less tired), but I didn't time it.
When lowering a moving chain into an existing kerf, the RS really wants to climb the sides of the kerf. I'll really have to be careful about that! (I've learned to insert the saw under slight throttle. If the chain is stopped, inevitably some sliver catches a tooth and the clutch can't get the chain moving.)
The RS seemed much more willing to cut to the side. I had to pay attention to keep from cutting circles. (If part of the bar is in an existing kerf, RM will dutifully stay lined up.)
The RS chain self fed much more eagerly than the RM chain. With the RM chain I could "hold it back", get a bit more engine rpm, and end up cutting faster. Not so with the RS. I also noticed no difference between 90% and 100% throttle.
Fuel usage was probably the same - lots: Two tanks for the bar-buried cuts, a third tank to finish bucking, and a fourth to make the five 16"x30" noodling cuts.
Bar oil use might have been less. This jibes with the lower engine rpm.
The RS didn't get dull any faster. The first sharpening was after the eight bar-buried cuts - right when I would have sharpened RM chain. This sharpening was easy! (In the past, the Stihl factory grind didn't match the specified files. It would take many, many swipes to reshape each tooth.) However, I did have to sharpen it 2 or 3 times to noodle one of the rounds. There was a really hard encapsulated limb stub in the round.
The wood chips on the ground were very similar. The chip lengths were the same. The RS produced wider chips and fewer narrow slivers.
And the biggest difference: Much less fine dust on the air filter! With RM I was having to stop every half tank of gas to clean dust dunes off the filter. (No, the RM was not dull.)
Conclusion:
I suspect that the safety vs non-safety chain aspect made little difference in this test. However, I now understand why there are no full chisel safety chains! For now, the RMC3 chain is back on the saw because I'm currently dicing up bark and cutting up small brush. I'm now open to the use of a variety of chain types.
(BTW, my first post here!)
