How long you cut between sharpening ripping chain

[BigOakAdot]

So Bob in that video you're measuring the angle from the cutter to the raker? Which is essentially a different way of figuring out what depth to set your rakers so they are even?

 

[BobL]

So Bob in that video you're measuring the angle from the cutter to the raker? Which is essentially a different way of figuring out what depth to set your rakers so they are even?

Sort of correct but it translates to a difference raker depth depending on the extent of the cutter wear.
OR
The rakers can be at different depths because the depth depends on the cutter length.

For new chain a 6º raker angle translates to a 0.025" for a gullet length of 0.25" i.e. approx a 10:1 ratio.
When cutter wears and needs sharpening and eventually the gullet reaches 0.5" , the raker should be 0.050" (not 0.025")
When gullet = 0.3" raker should be 0.030". gullet = 0.4" raker should be 0.04" etc

You can get raker depth gauges in 0.005" increments i.e. 0.025. 0.030. 0.035, 0.040. 0.045 etc but if you measure the raker angle with a DAF
a) cutter length is irrelevant as long as the angel stays constant.
b) you can set the angle to any setting in-between the 0.005" increments
Remember the cutters don't sit on the bar rails and act like little planes shaving the wood out of the kerf, instead the jump up off the bar and take a bite/chip out the wood. What determines the size of the chip is the raker angle - so it doesn't matter if the cutters are not even lengths provided the rakers are filed to a compensatory depth to generate the same raker angle.

And remember this is for a given drive sprocket pin count, saw power, cut width, log hardness, dryness of log etc
Of narrow softwoods with a large saw rakers angles as high as 9.5º can be sustained with resulting cutting speeds of a drunken monkey
On wide hardwoods with a small saw you might have to use 5º

The only person who can work out their optimum angles is the operator but I recommend starting with 6º and work it up (or down from there).

The easiest way to make an assessment is to make a test cut and then swipe the rakers 2/3 times, repeat the cut, swipe the rakers 2/3 more etc until the saw starts to grab - then you know you have gone too far and you make have to take 5/6 swipes off the cutters to back the angle off a bit, then measure the angle then you know you have optimised the chain.

 

[Quietfly]

It's a pain in the but to do this way but the results are definitely there.
@BobL has totally made a believer out of me.

 

[BobL]

It is painful to set up if you can maintain the rakers regularly 2/3 swipes every 3-4 touchups so but after while you get to work our chat keeps the whole chain in the zone. The old timers were not that far away from this. My dad only used raker gauges for the first half dozen or so sharpening then he would touch them up depending on how much powder the saw was generating.

 

[Quietfly]

It is painful to set up if you can maintain the rakers regularly 2/3 swipes every 3-4 touchups so but after while you get to work our chat keeps the whole chain in the zone. The old timers were not that far away from this. My dad only used raker gauges for the first half dozen or so sharpening then he would touch them up depending on how much powder the saw was generating.

So i've moved over to using the Grandberg file n Joint for sharpening and still using the DAF for the rakers and its made a HUGE difference in milling. i'm just waiting to get my big saw back.....

 

[wombler]

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