Is it 3/8 pitch or 3/8LP ?

[Franny K]

The mismatch then between them I gather is only due to the links being shallower in LP - why the drive links of 3/8 will not fit in an LP sprocket, but 3/8LP can imperfectly fit a 3/8 sprocket.

The 3/8 chain for 50 to 100cc saws has larger drive links that is at least in my opinion why the mis match works one way and not the other, at a rim type drive sprocket. The center of the rivet to the sliding surface is less for the 3/8lp or picco. It has been called 3/8 reduced which would probably be more informative. I think the low profile trademarked by Oregon means the cutter top is closer to the bar sliding surface than the regular chain. They had low profile .325 33, 34,and 35 LG and SL that used the normal .325 sprockets bar and drive I think even splicing pieces as well.

 

[Coralillo Lo Pro]

The 3/8 chain for 50 to 100cc saws has larger drive links that is at least in my opinion why the mis match works one way and not the other, at a rim type drive sprocket. The center of the rivet to the sliding surface is less for the 3/8lp or picco. It has been called 3/8 reduced which would probably be more informative. I think the low profile trademarked by Oregon means the cutter top is closer to the bar sliding surface than the regular chain. They had low profile .325 33, 34,and 35 LG and SL that used the normal .325 sprockets bar and drive I think even splicing pieces as well.

It took me awhile of getting into it to fully understand what low profile meant, that it wasn't just narrower chain like some narrow kerf chains, but that the profile was lower due to less material vertically in the links, and teeth that were also quite low. By my understanding, what makes it cut (and particularly mill) so well is that due to the low profile, side to side motion is minimized more than in almost any other chain, producing an exceptionally smooth surface and relatively small effective kerf. The higher the cutting edge of the teeth is off the bar rail, the more there will be side to side deflection, so narrow kerf chains that sit at conventional height still produce a fairly big effective kerf. One person in a past thread noted that milling with .325 .063 was some of the smoothest results he'd ever had, but the kerf was about as big as standard 3/8.

Bottom chain is 3/8LP, top is 3/8. Note matched rivet spacing of both, they are both technically .365 pitch. The subtle mismatch that doesn't allow interchange is in the shape and depth of the drivers.

 

[Lightning Performance]

Well, this part has been confusing for me and now I finally get it. I always heard LP/picco was actually .367 or .366 or .365, but as was already explained in this thread, it's not just LP/picco chain - all 3/8 is just a misnomer like "2x4". Regular 3/8 chain is actually the same (.366 or so) when you put calipers on it - I just checked mine - and both come in 1640 links in a 100 foot roll. That's why some people on here note that you say 3/8" the same way you say 2x4 in lumber because everyone who knows knows what 3/8 means in chain, but you shouldn't say .375 (though people and the industry commonly interchange 3/8"/.375" all the time) because it's not. The mismatch then between them I gather is only due to the links being shallower in LP - why the drive links of 3/8 will not fit in an LP sprocket, but 3/8LP can imperfectly fit a 3/8 sprocket.

The drivers are shaped different and occupy more or less space between sprocket or rim teeth. The sprocket is the worst part of the mismatch. I have wide segment 3/8 8p rims that will run lp better than 3/8 7p lp rims. The chain will lay on the rim if you put lp on standard rims. The driver is how a chain was meant to be driven. Those parts rotate on the rim segments when things are right. If not premature wear happens causing a beak in the lp drivers. Won't matter much because you already ruined the sprocket nose on your bar before that.

 

[Lightning Performance]

The 3/8 chain for 50 to 100cc saws has larger drive links that is at least in my opinion why the mis match works one way and not the other, at a rim type drive sprocket. The center of the rivet to the sliding surface is less for the 3/8lp or picco. It has been called 3/8 reduced which would probably be more informative. I think the low profile trademarked by Oregon means the cutter top is closer to the bar sliding surface than the regular chain. They had low profile .325 33, 34,and 35 LG and SL that used the normal .325 sprockets bar and drive I think even splicing pieces as well.

The NK also uses micro cutters that look similar to lp cutters but always wider.

 

[Coralillo Lo Pro]

The drivers are shaped different and occupy more or less space between sprocket or rim teeth. The sprocket is the worst part of the mismatch. I have wide segment 3/8 8p rims that will run lp better than 3/8 7p lp rims. The chain will lay on the rim if you put lp on standard rims. The driver is how a chain was meant to be driven. Those parts rotate on the rim segments when things are right. If not premature wear happens causing a beak in the lp drivers. Won't matter much because you already ruined the sprocket nose on your bar before that.

Any particular disadvantages to old roller nose sprockets like the Oregon and old McCulloch ones? Have a very nice condition 24/25" bar with roller nose on the low compression McCulloch 250 I got for $50 recently. Turns out to be one of those .404 .050 oddities of the old McCulloch's though only the driver sprocket is .404, cause of the roller nose the bar is a universal .050 bar. With mods to the tail mount and oil holes to make it 12mm Stihl, seems like it should be a great lo pro bar. Seems like 5-6 years ago I saw more of the old Oregon roller noses for sale, now the only ones available people want collector's prices on EBay for the roller nose tips. Cannon makes one new still but it seems bigger (2 3/4") for hot saws. This one is 2 1/2", I think the smaller Oregon ones are 2 1/4".

 

[Lightning Performance]

Any particular disadvantages to old roller nose sprockets like the Oregon and old McCulloch ones? Have a very nice condition 24/25" bar with roller nose on the low compression McCulloch 250 I got for $50 recently. Turns out to be one of those .404 .050 oddities of the old McCulloch's though only the driver sprocket is .404, cause of the roller nose the bar is a universal .050 bar. With mods to the tail mount and oil holes to make it 12mm Stihl, seems like it should be a great lo pro bar. Seems like 5-6 years ago I saw more of the old Oregon roller noses for sale, now the only ones available people want collector's prices on EBay for the roller nose tips. Cannon makes one new still but it seems bigger (2 3/4") for hot saws. This one is 2 1/2", I think the smaller Oregon ones are 2 1/4".

Finding parts is the disadvantage.

Machine works to use a new roller nose from Cannon is about the only other option. Finding General nose gear is about impossible or you pay more than a new Cannon nose assembly. Machine work for the rivet nose is fine if you can find the old three rivet Cannon/Oregon nose sprockets. I have them in stock now for myself. Finding General, Oregon, Craftsman, Mall and few others wasn't worth my time looking. Japanese parts are more plentiful globally then old North America stuff these days. Sugi sprocket nose parts and a few others aren't like looking for Remington four rivet stuff. Remington is well out of work tool range these days on parts prices.

 

[Coralillo Lo Pro]

Finding parts is the disadvantage.

Machine works to use a new roller nose from Cannon is about the only other option. Finding General nose gear is about impossible or you pay more than a new Cannon nose assembly.

A further glance at various forums and there was probably even less than I thought available awhile ago. Guys obsessed with speed have been buying roller noses up everywhere they could be found for awhile now. Like you say about long bars too, stuff can be found but it's only from picking and finding people ditching parents/grandparents belongings not knowing what they have. How I got that McCulloch. Everything on Ebay is gonna obviously cost too much because it's mostly people who know what they have selling to a national market. I might be able to get 6K Products to manufacture high quality American steel ones it I thought there was enough of a market but it's enough of a niche thing I don't know there would be any money in doing so.

 

[Franny K]

Any particular disadvantages to old roller nose sprockets ........ only the driver sprocket is .404, ......... seems like it should be a great lo pro bar. .....

Probably the thickness of the bar is a disadvantage. I have a medium radius hard nose Oregon 20" 72dl bar in 0.050 and it is thinner than a replacement sprocket nose Oregon bar. When you get into the longer hard nose bars at least with Oregon they seem to only be in 0.063 guage and thicker.

 

[Coralillo Lo Pro]

Probably the thickness of the bar is a disadvantage. I have a medium radius hard nose Oregon 20" 72dl bar in 0.050 and it is thinner than a replacement sprocket nose Oregon bar. When you get into the longer hard nose bars at least with Oregon they seem to only be in 0.063 guage and thicker.

Yeah, will put calipers on to compare but this old McCulloch bar seems pretty substantial for a .050 bar. I think the purpose built GB lo pro milling bars are considerably thinner - I tried cross cutting with my 36" GB lo pro bar one day and it just flexes all over the place. Funny, guessed wrong - the old McCulloch .050 25" bar is .19" thickness, exactly what my 36" GB lo pro bar is, as is my Stihl 42" .404 bar. I guess all the flex in the 36" GB lo pro is from how narrow bellied the bar is in comparison to regular bars. My 20" GB lo pro is only .16" though, where a beefy 20" Stihl 3002 mount .063 hardnose is .19". Amazing things, calipers. Change many of your preconceptions. My 72" GB titanium .063 is .26", I'd expect a quality 42" .063 bar to be a bit thicker than my Stihl is.