What dictates the chain pitch and size. Stihl - Husqvarna compatibility...

[Coreytroy]

I have a Stihl MS380 and have just purchased a backup saw, a Husqvarna 137.

The Stihl runs a 063 chain.
The Husqvarna runs a 058.

Is it possible to change the drive sprocket of the Husky to fit the same chain as the Stihl?

Or is this topic a bit like wanting a Holden part to fit a Ford?

[Andyshine77]

.050" .058" and .063" refers to the thickness of the drive links. .325 3/8 and .404 is the spacing between three rivets of the chain, it's known as the chains pitch. The bar and chain have to have the same driver thickness. The drive sprocket on the saw will work with any of the chain driver gauges. however the bar nose sprocket and the drive sprocket, has to be the same pitch as the chain. 

[joe_indi]

In metric those are 1.3, 1.5 and 1.6mm respectively. So  the difference in drive link thickness between Stihl and Husky is only 0.1mm, which is no more once your Husky bar has had about four chains run on it.
The other difference is that the 18" Stihl bar is actually only 17". So the number of drive links on a Stihl 18" 3/8" chain is 66, while its 68 on the Husky chain.

[webgal]

You don't have to touch the sprocket on either saw if they are both .325 pitch. (Let us know the chain type if you aren't sure.)  Next the tricky thing is you would be hard pressed to commonly find a .325 x .058 bar with your Stihl mount. Likewise, a .325 x .063 bar for your Husky. Yes, nose changes can happen and other fiddling around. At any rate, those match/fit types are difficult to come by.
My suggestion would be, if both saws have .325 pitch sprocket (pitch doesn't matter on the sprocket) to get two new bars both in .325 x .050 and then you can buy chain in bulk. Sorry the drive link counts will be different. For instance based on an 18" bar the Stihl will take 74 and the Husky generally 72. So it's not like you can grab any chain for either machine and have it fit. But you can buy chain in bulk, make and mend to suit.

[sawguy21]

Something seems amiss here. You say the Husky is .058. The 137 we see in North America normally uses 3/8 .050, nobody makes this chain in .058. .325x.058 would be possible but that saw is a little small to be running this chain. It certainly won't drive the full size 3/8.

[JohnG28]

That's what i was thinking sawguy. It would be lo pro 3/8" too. I don't remember having seen that in .058.

[webgal]

Yes, that is the big "if" question. Folks make so many sprocket changes and pick up second hand equipment anything is possible. Let's hear him out.

[joe_indi]

Maybe in some countries   low profile 1.3mm 3/8 pitch is standard on the 137.
Here I have seen the 136 and 137 with 14" bars running 1.3mm .325 semi chisel chains supplied as standard.
When the bars are a bit worn 1.5mm .325 chains were used.
I have even seen a couple of 137s running 14" Carlton K2 chains (chisel)