Chain size 3/8 vs .325

There a few different thickness in chain. One of my saws is 3/8 the other .325. It would seem to me that the
thicker chain would have to work harder because it taking more wood out. I used to think the bigger chain was better but unsure about that now. The 3/8 does looks tougher.

You're right. The 3/8 chain is kind of a holdover from the old days. It's just a little beefier and probably better suited to a saw with higher horsepower. For most saws these days, .325 is plenty good enough. It cuts just as well (or better), is lighter, and requires less power to do the same job. There's an unfortunate lack of standardization in the chain saw chain business, so it gets pretty confusing. You're usually ahead to stick with the chain, bar and sprocket specified for your saw which, in the case of older saws, is often 3/8 pitch. Chain gauge is another variable. The chain for my 346xp is .325 50 gauge. They say it cuts 25 percent faster than older, heavier gauge .325 pitch chain. I think that's probably true.

Perhaps in theory, the .325 should be faster with all factors being equal. I have tried both on a Dolmar 5100s and with my novice abilities, I cannot tell the difference in speed. What I did notice is that the 3/8 seems to hold its sharpness a little better and is cheaper where I shop. I think I would be happy with either one.

Huh?

.325" PITCH and 3/8" PITCH pertains to the spacing between the rivets, not the width of the kerf being cut, which is what I believe you are talking about when you refer to "the thickness". There are narrow kerf varities of .325" chain, standard-kerf varieties, and then there are the few sorts of .325" pitch chain (Stihl RS, for example) that use noticeably larger cutters.

There are a host of issues beyond the width of the kerf to consider - chip clearance on longer bars being foremost among them - in determining which chain is "better" than another.

There are different kinds of chain because they do different jobs. .325" pitch narrow kerf (Oregon 95vp, for example) is a great chain for a Husqvarna 346xp with a 15" bar. But it would be totally inappropriate on a Stihl 066 with a 36" bar, if for no other reason that a bar thin enough for .325NK would be flimsy as can be at any length over 20" (heck, they're pretty flexy over 16" anyway).

Generally it is safe to state that saws under 40cc are happiest with 3/8"LP chain, 40-60cc is happiest with .325" chain (whether of the narrow kerf variety or not) and saws over 60cc are at their best with 3/8" chain. This presupposes that these are stock, modern saws.

.....and the terminology is confusing. computeruser is right: the pitch refers to the distance between the links. Why one is expressed as a fraction and the other as a decimal is another point of confusion.

21/64ths is just larger than .325. Going to 128ths isn't much better in that it doesn't equal out to .325". It's probably easier for people to visualize it if it's in a decimal.

Good advice as always from CU. I enjoy your posts on the Arborist website too.

Well, 0.325=13/40 exactly, but I'll agree that's not very helpful. Would be better if they just used .375 instead of 3/8. There's a .404 out there also.

It goes against some standards but I have gotten to where when I am making drawings for the shop I put all the dimensions in decimal. The only thing I still put as a fraction is tap sizes. I do this because most people are using digital micrometers and calipers and with today's educational system too many just cannot handle doing the conversion so basically they just have to make the display look like the number on the drawing.:-O