Why couldn't low profile chain have been .375 pitch?

[KiwiBro]

Was it the same marketing geniuses that came up with striped socks or is there a good reason they had to lower the pitch slightly?

Thanks in advance.

 

[Chris-PA]

? It is.
http://www.oregonproducts.com/pro/products/chain/91VX.htm

 

[KiwiBro]

Thanks Chris. I've seen some of it referred to as .365 rather than .375, and the bar sprocket noses are slightly different also.

Is it just a Stihl Picco thing or will all 3/8 noses be fine with low profile chain? Perhaps it's not the pitch as such but the shape of the sprocket teeth?

Would a 3/8 rim work for 3/8 low profile chain? If not then is the pitch really 3/8 or less?

 

[Chris-PA]

Thanks Chris. I've seen some of it referred to as .365 rather than .375, and the bar sprocket noses are slightly different also.

Is it just a Stihl Picco thing or will all 3/8 noses be fine with low profile chain? Perhaps it's not the pitch as such but the shape of the sprocket teeth?

Would a 3/8 rim work for 3/8 low profile chain? If not then is the pitch really 3/8 or less?

As far as I know all 3/8 chain is really 0.365" or thereabouts. The lo pro chain uses a different "tooth" shape on drive and tip sprockets, as the chain chassis is different. Effectively the tie strap sits lower and the drive tang is different. Low pro bar tip teeth have a flattened off shape as opposed to the pointy teeth on regular 3/8.

I recall that there was a really extensive thread on this in the Milling forum some time ago, but I do not have a link.

 

[SawTroll]

-

If I order a 100 ft roll of .375 chain, then, and it is only .366 do they still owe me a couple feet or did I get a few free cutters? Dang free stuff.

All 3/8" chain actually is about .366 pitch. Calling them .375 simply is wrong - 3/8 is an approximate number, while ,375 gives the impression of being a much more accurate number - which it isn't, just a "translation" of 3/8.

Implicit in that is that the pitch of 3/8" and 3/8" lo-pro is the same - but that doesn't mean that the sprockets interchange, as the chassis of the two types are very different.
The lo-pro sprockets need to have a larger diameter, to compensate for the lower chassis. When the pitch is the same, it is the rivets that need to run at the same diameter, not the bottom of the chassis.

Running lo-pro on a regular 3/8" sprocket is like running with an extremely worn sprocket - not good at all!

 

[mdavlee]

Grande dogg sad a 404-8 sprocket works good milling with the lo pro. I've not measure one but I do have a loop here and a 404 sprocket.

 

[heimannm]

The profile (height of the tie straps if you will) of the Lo Profile chain is different so it needs a slightly smaller radius as it goes around the sprocket. A .404 sprocket can be made to work but it must be turned down slightly, do a little searching and you will find a lot of information on this topic already posted.

Mark