mtngun
Addicted to ArboristSite
I'm gradually regrinding the lo-pro injecta-sharp to 10 degrees, in 5 degree increments. This was the first time it had been sharpened, so it got ground to 25 degrees. Reluctant to shorten the cutters, I set the grinder so that only outer half of the cutter was getting ground, while the inner half is still dull. You can kinda see that in this pic.
The plan was to run the injecta-sharp all day or until it stopped cutting decently, just to see how long it would hold up. From time to time I did a mini-speed test, like this. I marked out 24" on the log, and simply timed the cut over that 24" without pausing to insert wedges, etc.. This is an easy test that anyone can do in the field. If you don't have a stop watch, you could just count "1000, 1001, 1002, etc." It would be interesting to see how your cutting speeds compare to mine with different saws and different woods.
Here are the speeds for injecta-sharp with the half sharpened/half dull 25 degree top plate, all in doug fir:
slab #1, 15" - 16" width including bark, 0.4 inch/sec.
slab #6, 15" - 16" width including bark, 0.3 inch/sec (slowing as it dulls)
slab #10, 10 1/4" cant, 0.57 inch/sec
By slab #10, it felt like it was cutting slower, and the RPM's were only 7500 - 8000 most of the time. Also, the chain tension was getting a little sloppy.
I decided to take the injecta-sharp off and install a freshly sharpened WP lo-pro ripping chain. Here's how it cut on the same cant:
slab #11, 10 1/4" cant, 0.85" inch/sec.
Today's conclusions about lo-pro injecta-sharp: It stayed reasonably sharp for 6 - 8 passes, about the same as standard 3/8 ripping chain. The chain did not need to be tightened for the first 10 passes, though it would have needed tightening had I left it on for additional passes. So ...... the injecta-sharp didn't work miracles, but it did "OK."
The day started with this log, left over from my previous trip to the woods.
Then I moved to another doug fir blowdown about 100 yards away. Only 16", but straight and not too many limbs by local standards. Note the position of the stump.
The plan was to run the injecta-sharp all day or until it stopped cutting decently, just to see how long it would hold up. From time to time I did a mini-speed test, like this. I marked out 24" on the log, and simply timed the cut over that 24" without pausing to insert wedges, etc.. This is an easy test that anyone can do in the field. If you don't have a stop watch, you could just count "1000, 1001, 1002, etc." It would be interesting to see how your cutting speeds compare to mine with different saws and different woods.
Here are the speeds for injecta-sharp with the half sharpened/half dull 25 degree top plate, all in doug fir:
slab #1, 15" - 16" width including bark, 0.4 inch/sec.
slab #6, 15" - 16" width including bark, 0.3 inch/sec (slowing as it dulls)
slab #10, 10 1/4" cant, 0.57 inch/sec
By slab #10, it felt like it was cutting slower, and the RPM's were only 7500 - 8000 most of the time. Also, the chain tension was getting a little sloppy.
I decided to take the injecta-sharp off and install a freshly sharpened WP lo-pro ripping chain. Here's how it cut on the same cant:
slab #11, 10 1/4" cant, 0.85" inch/sec.
Today's conclusions about lo-pro injecta-sharp: It stayed reasonably sharp for 6 - 8 passes, about the same as standard 3/8 ripping chain. The chain did not need to be tightened for the first 10 passes, though it would have needed tightening had I left it on for additional passes. So ...... the injecta-sharp didn't work miracles, but it did "OK."
The day started with this log, left over from my previous trip to the woods.
Then I moved to another doug fir blowdown about 100 yards away. Only 16", but straight and not too many limbs by local standards. Note the position of the stump.