What does one of those (progressive depth gauge guide) look like? I thought all dept gauges was the same. The dept gauge I used was a feeler gauge, around 20-22,000 under straight edge from tooth to tooth.
Your method is effectively a "non-progressive" depth gauge tool. The disadvantage is that it takes the average of the two teeth to set the depth gauge height, rather than customizing the depth gauge to the height of the tooth that immediately follows it. If your two teeth are different heights, you won't have the optimal height for the tooth associate with that gauge. Thus the need to keep all teeth the same. In the case where someone is counting strokes, and sharpens a bit harder/better with one hand then the other, all of the teeth on one side tend to get longer than the teeth on the other (unless the operator compensates with an extra stroke or two on the "weak" side.) With a non-progessive gauge, all of the teeth on one side get a bigger bite than those on the other, causing the chain to want to cut on a curve. A similar problem can happen when your cutters on one side are damaged by hitting a rock and need to be sharpened way back to get them working properly, then the operator doesnlt bring the other side in to match, and uses a non-progressive tool to set the depth gauges.
In addition,
if you keep the cutters all the same length, it works just as well as a progressive guide, at least when the chain is relatively new. However, as the cutters get sharpened back, it all does not change the depth gauge height in relation to the cutter as that cutter gets further from the depth gauge. For best performance, that relationship should change. You'll always be a .020-.022" with your method, and performance will drop off slightly as you sharpen back toward the end of the tooth's life.
Non-progressive depth gauge tool (The second one averages the two teeth and set the depth gauge a fixed amount below that, The first one bridges across two teeth, then extends that line out to the next depth gauge. If the two teeth are different, that extended line will be too high or too low.)
With progressive depth gauges, the tool rests on top of one tooth, has a hole for the depth gauge to poke through, and the other end rests down on the chain link. This customizes the depth gauge to the tooth which follows it, as it should be. The height of the preceding or following tooth does not interfere with the depth gauge setting.) Both of the tools shown have two options: one setting for softwoods, and the other for hardwoods (I use the hardwood setting all the time, since 90% of the time I'm cutting hardwoods. It still works OK in softwood, thoug If I knew I were going to be doing a ton of softwood, I might sharpen differently.) The first one I bought at a Husqvarna dealer years ago, before the second style was even available. The second one shown is attached to what some refer to as the "Swedish roller guide" the depth gauge tool flips out when needed. The roller part is used as a guide for sharpening the cutters. It's sold a most Husqvarna dealers. If I recall correclty, I think a local Stihl dealer also had them (??)