Back in part one of chain sharpening, we took a look at the filing tables to ascertain the file sizes and angles that we'd need to use to maintain our chain properly.
After the jump we'll take a look at how we should decide where to start filing.
Deciding Where To Start
How would you choose which cutter to start filing? When I pose this question whilst teaching, one common answer is along the lines of "whichever one is on top".
But it's not quite that simple (you knew it wouldn't be didn't you?). So, how do we go about selecting the first cutter to be filed? Fortunately it's easy, and we don't have to try finding a secret mark on one cutter, or find where the continuous chain has been joined - you just need to find the shortest one.
There's a very simple rule to this, and it's that when you have finished filing all of your cutters, they must be the same length. If they are not, you'll find that the chainsaw will not cut straight and it's disconcerting to find your chainsaw has cut the timber in a graceful arc.
If all your cutters are the same length, then take another look and see if any are more damaged than the others - if so, tidy these up first.
Once you've found the shortest / most damaged cutter, it's time to sharpen it; place the saw in a vice to keep it steady, don't try to hold it between your legs or sit on it. Ideally use a file guide to ensure that you get the right angle - don't be tempted to guess what 30o or 25o looks like. The angle shown on the guide should be in-line with the chain / guide bar.
Once you've sharpened this first cutter, measure the length of the cutter (shown in the picture, right). You can use a nut and bolt for this if
you're a cheap-skate you want to (I do), but obviously calipers are more accurate.
Now for the Dave's 'Tip Of The Day' - mark the cutter you've just started with. It's your chance to colour in - just use a permanent marker and colour the top of the cutter (called the top plate). This will ensure that once you sharpened all the others and you've worked your way around the chain, you won't carry on by filing the one you started with!
Only file the cutters that are on the other side of the bar to the one you're standing on. If you notice the arrangement of cutters on the chain, you'll see that they are on alternate sides - you sharpen all those on one side, then turn the saw around and do the other.
Once you've completed all the sharpening, you must remove the burrs that have formed during your filing; this is easily done by rubbing a block of wood up against the cutters. This will get rid of the wire edge and ensure that the chromium plating is not removed when you start cutting for real.
So we've now got sharp cutters and de-burred them - the depth gauges come next.