Why don't more people run PS3 chain instead of 325 on 50CC saws?

[Philbert]

Oregon already has/had a .325 low profile chain. I have some discontinued yellow label 34LG low profile chisel. They still sell the 33/34/35SL low profile chisel safety chain.

Were these rally 'low profile' cutters?

They have not made those in a l-o-n-g time. Listed as 'obsolete' in 2010 Oregon guide. Not even listed in their sharpening guides anymore. https://online.flippingbook.com/view/276256/162/



The 'Speed Cut Nano' uses different sprockets and bars than conventional .325 chain.



Philbert

 

[Farmchuck]

Were these rally 'low profile' cutters?

They have not made those in a l-o-n-g time. Listed as 'obsolete' in 2010 Oregon guide. Not even listed in their sharpening guides anymore. https://online.flippingbook.com/view/276256/162/

View attachment 188868 View attachment 188869

The 'Speed Cut Nano' uses different sprockets and bars than conventional .325 chain.

View attachment 188870

Philbert

That 34lg was good cutting chain!
In my humble opinion of course.

 

[Dub11]

Were these rally 'low profile' cutters?

They have not made those in a l-o-n-g time. Listed as 'obsolete' in 2010 Oregon guide. Not even listed in their sharpening guides anymore. https://online.flippingbook.com/view/276256/162/

View attachment 188868 View attachment 188869

The 'Speed Cut Nano' uses different sprockets and bars than conventional .325 chain.

View attachment 188870

Philbert

So would this make the speed cut nano not .325 technically?

 

[Philbert]

So would this make the speed cut nano not .325 technically?

Technically, 'pitch' really refers to the spacing of the drive links on the chain, and how they engage with the drive sprocket. '0.325 inch' pitch chain means that the tips of the drive links are 0.650 inches apart (for some reason we divide the spacing by 2 on saw chain).


Since it is hard to accurately measure the drive link tips (they wear, and move around) we measure the spacing between 3 rivets and divide by 2, but if you shift the lines over on the classic illustration below, you can see how they also align with the tips of the drive links.



So, .325 pitch chain matches .325 sprockets. But the actual cutters can be taller or shorter (low profile), wider or narrower (narrow kerf), shorter (some carving chains), or even missing (skip-tooth); and the drive link gauge can be thinner; and still fit the same drive sprocket. Same pitch.

As a practical matter, once chains require special sprockets or guide bars (e.g. narrow kerf and most low profile chains), I consider them to be a 'different' pitch chain. E.g. with 3/8 low-profile/Picco and full-sized 3/8 chain, the spacing ('pitch') is the same, but the shape of the drive links is different, requiring different sprockets.

Philbert

 

[Dub11]

Technically, 'pitch' really refers to the spacing of the drive links on the chain, and how they engage with the drive sprocket. '0.325 inch' pitch chain means that the tips of the drive links are 0.650 inches apart (for some reason we divide the spacing by 2 on saw chain).
View attachment 188886

Since it is hard to accurately measure the drive link tips (they wear, and move around) we measure the spacing between 3 rivets and divide by 2, but if you shift the lines over on the classic illustration below, you can see how they also align with the tips of the drive links.

View attachment 188888

So, .325 pitch chain matches .325 sprockets. But the actual cutters can be taller or shorter (low profile), wider or narrower (narrow kerf), shorter (some carving chains), or even missing (skip-tooth); and the drive link gauge can be thinner; and still fit the same drive sprocket. Same pitch.

As a practical matter, once chains require special sprockets or guide bars (e.g. narrow kerf and most low profile chains), I consider them to be a 'different' pitch chain. E.g. with 3/8 low-profile/Picco and full-sized 3/8 chain, the spacing ('pitch') is the same, but the shape of the drive links is different, requiring different sprockets.

Philbert

I always have read that 3/8s lp/ picco is .365 instead of .375. So that was making wonder after you said different sprockets is this new .325 maybe really .315 or something?

 

[Philbert]

I always have read that 3/8s lp/ picco is .365 instead of .375. So that was making wonder after you said different sprockets is this new .325 maybe really .315 or something?

3/8 low-profile and full 3/8 have the same rivet spacing:

100 feet = 1,200 inches
1,200 / 1,640 = 0.7317 inches
But since we divide by 2 (?) 0.7317/2 = 0.36585 inches. A bit short of 0.275.

Think of it as a 'nominal' measurement (e.g. '2 by 4' studs really being 1-3/4 X 3-3/4", or Subway 'foot long' sandwiches maybe not being a full 12 inches). Either way, they are the same in that regard.

Philbert

 

[radio]

Were these rally 'low profile' cutters?

They have not made those in a l-o-n-g time. Listed as 'obsolete' in 2010 Oregon guide. Not even listed in their sharpening guides anymore. https://online.flippingbook.com/view/276256/162/

Philbert

Yes they are real low profile. The LG was discontinued but the SL is still being sold as far as I know: http://en.oregonproducts.com/pro/products/chain/33_34_35SL.htm

 

[Deets066]

3/8 low-profile and full 3/8 have the same rivet spacing:

3/8 picco is not the same as regular 3/8.
That’s why they each have their own bars and sprockets.

I always have read that 3/8s lp/ picco is .365 instead of .375. So that was making wonder after you said different sprockets is this new .325 maybe really .315 or something?

Wonder why if picco is actually.365, then why are the drive sprockets larger than regular 3/8?

 

[chipper1]

3/8 picco is not the same as regular 3/8.
That’s why they each have their own bars and sprockets.




Wonder why if picco is actually.365, then why are the drive sprockets larger than regular 3/8?

That's right.
If you want a picco sprocket you have to turn a 404 down to get it the proper size.
I have all the specs somewhere and probably some pictures to, but it was from yrs ago back when guys were still talking about all the stuff lol.
Just because guys run picco on standard 3/8 sprockets and bars that doesn't make it right, take a look at them afterwards and tell me if it's right.

 

[Philbert]

3/8 picco is not the same as regular 3/8.
That’s why they each have their own bars and sprockets.

Right. But the rivet spacing ('pitch') is the same: 3/8 inch (nominal).

They use different sprockets because the drive links are shorter, and have a different profile. 'Picco' chains do not correctly seat into a full sized 3/8 pitch sprocket, and full sized 3/8 pitch drive links are too big to fit into smaller 'Picco' sprockets. It's like a short guy and a tall guy trying to fit into pants with the same waist size but very different inseams.

They use different bars only due to the sprocket nose (otherwise, a hard nose bar could run any pitch chain of the correct gauge).

Wonder why if picco is actually.365, then why are the drive sprockets larger than regular 3/8?

If you want a picco sprocket you have to turn a 404 down to get it the proper size.

The different sprockets fit the profile of each chain. 3/8 low profile ('Picco') fitting a turned down .404 is just by chance: when you reduce the diameter of the sprocket it fits the smaller drive links, and reduces the spacing between the slots. Someone just happened to discover that it worked.

Philbert

 

[Dub11]

3/8 picco is not the same as regular 3/8.
That’s why they each have their own bars and sprockets.




Wonder why if picco is actually.365, then why are the drive sprockets larger than regular 3/8?

IDK I only have one saw that runs lp

 

[Philbert]

Yes they are real low profile. The LG was discontinued but the SL is still being sold as far as I know: http://en.oregonproducts.com/pro/products/chain/33_34_35SL.htm

Than is a European Oregon website, which still lists a lot of the older technical information that I wish the US site still did. The chain is not listed in the current Oregon Forestry catalog:
https://online.flippingbook.com/view/276256/

If you can still get it, that would be a find. Buy a bunch if you like it.

Philbert

 

[radio]

Than is a European Oregon website, which still lists a lot of the older technical information that I wish the US site still did. The chain is not listed in the current Oregon Forestry catalog:
https://online.flippingbook.com/view/276256/

If you can still get it, that would be a find. Buy a bunch if you like it.

Philbert

The problem with the SL is that it has safety bumpers, big ones. The LG is much better.

 

[chipper1]

But

But is not needed in the sentence. I was referring to deets comments and him to yours, what was said was right, no butts about it!
Now if you wanted to say also or something on those lines that would be more "fitting".

As a practical matter, once chains require special sprockets or guide bars (e.g. narrow kerf and most low profile chains), I consider them to be a 'different' pitch chain. E.g. with 3/8 low-profile/Picco and full-sized 3/8 chain, the spacing ('pitch') is the same, but the shape of the drive links is different, requiring different sprockets.

You may want to remove this .
Although I understand where you're coming from it makes no sense because you know what they are measuring and it doesn't correspond to "pitch", so you can do as you like as a practical matter, but it's not correct.

The different sprockets fit the profile of each chain. 3/8 low profile ('Picco') fitting a turned down .404 is just by chance: when you reduce the diameter of the sprocket it fits the smaller drive links, and reduces the spacing between the slots. Someone just happened to discover that it worked.

Philbert

The point I was making here is about the diameter, not the chance that it fit. Nice that it will work if needed in an application though.

 

[Philbert]

You may want to remove this.
Although I understand where you're coming from it makes no sense because you know what they are measuring and it doesn't correspond to "pitch", so you can do as you like as a practical matter, but it's not correct.

Depends on how one defines and understands the term 'pitch'. (For some, it is a black, sticky substance used to patch roofs; an action of a baseball player; or even the field where sports are played).

If you want a picco sprocket you have to turn a 404 down to get it the proper size.

Or buy a STIHL Rim Sprocket 00006421240 (or the equivalent).


Philbert

 

[chipper1]

Depends on how one defines and understands the term 'pitch'. (For some, it is a black, sticky substance used to patch roofs; an action of a baseball player; or even the field where sports are played).

Philbert

Really .

Or buy a STIHL Rim Sprocket 00006421240 (or the equivalent).


Philbert

The point I was making here is about the diameter, not the chance that it fit. Nice that it will work if needed in an application though.

 

[Wonkydonkey]

Just a follow on of the pitch of a chain std 3/8 and 3/8 lopro

On another forum, there was a guy using a 660 I think. With a 3/8 lopro chain. He was milling some larch on a logsol mill. It zipped through it fast. But he got pissed when the chain kept snapping.
Here’s a pic or 2 of the chain, notice the marks highlighted by red arrows



Here’s some broken bits



It turned out this was the reason the chain had kept snapping

It’s a std 3/8 spur. It took a bit of time getting pics and piecing it all together..
I'm not sure how a rim sprocket would have behaved

Edit, I think the guy had to ditch the chain,,, even after changing to the proper size sprocket, because the chain had been weakened

 

[chipper1]

Just a follow on of the pitch of a chain std 3/8 and 3/8 lopro

On another forum, there was a guy using a 660 I think. With a 3/8 lopro chain. He was milling some larch on a logsol mill. It zipped through it fast. But he got pissed when the chain kept snapping.
Here’s a pic or 2 of the chain, notice the marks highlighted by red arrows
View attachment 189016

View attachment 189020
Here’s some broken bits
View attachment 189017
View attachment 189018

It turned out this was the reason the chain had kept snapping
View attachment 189019
It’s a std 3/8 spur. It took a bit of time getting pics and piecing it all together..
I'm not sure how a rim sprocket would have behaved

Edit, I think the guy had to ditch the chain,,, even after changing to the proper size sprocket, because the chain had been weakened

You may get away running 3/8 picco without the proper bar and sprocket on a low powered saw, but it will show up when there is more power and a high load situation.

 

[Farmchuck]

Right. But the rivet spacing ('pitch') is the same: 3/8 inch (nominal).

They use different sprockets because the drive links are shorter, and have a different profile. 'Picco' chains do not correctly seat into a full sized 3/8 pitch sprocket, and full sized 3/8 pitch drive links are too big to fit into smaller 'Picco' sprockets. It's like a short guy and a tall guy trying to fit into pants with the same waist size but very different inseams.

They use different bars only due to the sprocket nose (otherwise, a hard nose bar could run any pitch chain of the correct gauge).
View attachment 188995


The different sprockets fit the profile of each chain. 3/8 low profile ('Picco') fitting a turned down .404 is just by chance: when you reduce the diameter of the sprocket it fits the smaller drive links, and reduces the spacing between the slots. Someone just happened to discover that it worked.

Philbert

Good understandable analogy!

 

[Philbert]

On another forum, there was a guy using a 660 I think. With a 3/8 lopro chain. He was milling some larch on a logsol mill. It zipped through it fast. But he got pissed when the chain kept snapping.

The smaller pitch chains are designed for lower powered saws, so they use thinner, lighter components (tie straps, rivets, etc.). For example, Oregon only recommends their Type 91 (3/8 low profile) chain up to 40cc and 18" bars in some of their literature. I have certainly seen it on larger saws, but you can see where a 660 could snap it.

Philbert