hmmmmm i wonder if harder is becoming more brittle??? i wonder if there is combination between hardness and ductileness is the answer... but as you said with bobl tesing the stihl was softer...
If you read my "report" it said there was very little between oregon/stihl/carlton, and for all practical purposes they were the same. Based on what I measured so far I would have to increase the measurement sample size considerably to try to differentiate between all 3. These are the realities of measuring real materials. (but also see problem below)
do you know how he did it?
It was done with a bog standard Vickers Hardness indenter. Diamond Point - RC hardness range. the instrument was calibrated using an NIST standard so these are pretty reliable results.
if the chroming on the stihl was harder would that show up on a tester or would it be to thin and only the tooth material and its heattreating show up?
That is a definite problem. I tested both the chromed and unchromed sufraces and there is no difference between them. But as the diamond indenter is bigger than the thickness of the chrome, it is almost certainly just measuring the hardness of the steel and not the chrome so there could be small differences in the chrome that I have not picked up. Measuring this is a lot trickier and would actually require a bigger more solid piece of chrome from the chain manufacturers.
Besides we don't really care about hardness, what we care about is;
a) How sharp an edge can be generated (carbon steels form very sharpest edges but lose sharpness quickly because they are brittle)
b) How long that edge holds up (that's related more to short and long term toughness which is different from hardness)
c) How easily that edge is reformed (how easily is it to sharpen, eg carbide chains are very hard to resharpen)
These are not something that can be "tested" with a specific machine(s) but is best done by timed cuts in real wood. I have 3 Stihl and 6 Carlton chains that I use on my mill and cannot differentiate between the
initial cutting speeds obtained with freshly sharpened stihl or carlton chain. I mill slabs in biggish (30"+) aussie (ie very) hardwood and if I get an 8"/minute initial cutting speed with my 076, I figure that I'm doing well. The limiting step in initial cutting speed is not the brand of chain but how carefully and consistently I can sharpen. This is as good as one can probably measure a)
b) can be assessed by comparing the initial cutting speed with the final cutting speed, ie speed towards the end of cutting +8' long slab, since it will indirectly tell you how much of the edge has worn off during the cutting. If I start with an initial 8"/min and get 6"/min as a final speed I consider that very good going, but sometimes I get final speeds as low as 4" or even 3"/min. On softer hardwoods I cannot tell the difference between the initial and final speeds for the two brands of chains since I reckon the final cutting speed is influenced more by how careful and consistently I can sharpen and set rakers to begin with. However, on really hard wood the final cutting speeds are generally higher when using the Carlton chains. I now rarely let my cutting speeds drop below 4"/min even on the widest slabs. On wider and longer slabs ( eg 45" wide 12' long) sometimes the wood is so hard, I pull the saw out and touch up half way through a slab. Somewhere I read where someone was cutting 5ft wide x 16 ft long Aussie hardwood slabs and they were sharpening up 3 times during one slab.
c) is somewhat irrelevant since I don't find either brand of chain hard to sharpen
maybe the sthil stuff is TOO hard for our hard woods????
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