I set the rakers on both my full comp 60" milling chains today.
To read correctly a DAF needs to be held square across the cutter and raker, so freehand holding a DAF leads to an uncertainty in measruing the cutting angle of about +/- 0.3º .
To get around this I clamped a rebated block of wood onto the bar for the DAF to lean up against and so the chain can still slide past easily onto the bar
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Measuring the cutting angle is then
1) Remove chain from bar and zero DAF against a marked position on bar
2) Replace chain and mount block of wood as shown
3) Move cutter of interest above marked position on the bar
5) Place DAF down onto cutter edge,
6) Lightly push back of DAF flat up against block and rotate DAF down till it makes contact with the top of the raker.
Care should be exercised to ensure the DAF does not make contact with adjacent rakers and cutters.
Before filing my ripping chains I had an average raker angle of about 4.5º but the range of angles was between 2.9 and 5.2º - ie all over the place.
The raker of interest is then slid a little away from the wooden block and filed, then slid back over the marked position and remeasured.
Repeat until you get 6º
BobL, I watched your Youtube video, and was impressed, but thought I'd experiment with a slight variation of the system.
I made a very rough prototype and experimented with it. This prototype is definitely not a thing of beauty, but it seems to work perfectly. By having a window in the block against which one holds the DAF vertical, one can eliminate the "The raker of interest is then slid a little away from the wooden block and filed, then slid back over the marked position".
Simply measure, file, re-measure. No moving the chain at all until one is ready to do the next raker.