# 3/8 lo pro and 3/8 sprocket differences?



## B_Turner (Aug 23, 2009)

I am fairly new to the 3/8 lo pro thing. I know it's been discussed, but I can't remember the answer.

Is 3/8 lo pro actually .365? Can I run 3/8 lo pro chain on a 3/8 sprocket?

Or 3/8 regular on a sprocket that came with lp originally?


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## mowoodchopper (Aug 23, 2009)

3/8 is 3/8

Low pro is cutter design.

yes you can :hmm3grin2orange:


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## ray benson (Aug 23, 2009)

I wouldn't mix them. Here is a pretty good thread on the issue.
http://www.arboristsite.com/showthread.php?t=39384&highlight=3/8+low+pro+full+size


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## B_Turner (Aug 24, 2009)

ray benson said:


> I wouldn't mix them. Here is a pretty good thread on the issue.
> http://www.arboristsite.com/showthread.php?t=39384&highlight=3/8+low+pro+full+size



I still come away a little befuddled. I can see not mixing the bars andbar sprockets between them, but the difference when it comes to drum sprocket vs floating rim is not quite clear to me.

I need to compare each chain on each of those sprockets and really look at how the tang fits each. Maybe then I'll understand a little better.

One reason I am thinking about comparing is that then I can compare cutting speed between certain small saws of mine using the same lp chain.


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## TraditionalTool (Aug 24, 2009)

ray benson said:


> I wouldn't mix them. Here is a pretty good thread on the issue.
> http://www.arboristsite.com/showthread.php?t=39384&highlight=3/8+low+pro+full+size


Ray,

That is a confusing thread, they are talking about 3/8, 3/8 lp, and 3/8 picco.

It was my understanding that picco is it's own beast, and because of such it does make sense that the tang is different on the chain, but doesn't regular 3/8 and 3/8 LP have the same tang on them?

Mathematically, the chain and sprocket/rim have to be the same, or it couldn't be 3/8" pitch. However, a different tang as on the picco chain, would render it a red headed step child.


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## ProMac1K (Aug 24, 2009)

I thought Picco was a Stihl-exclusive term for 3/8 LP. 

One of my saws came with a LP chain on a 3/8 bar. Granted, it was a .058 bar, but that was the only mismatch. It operated just fine. Just bought a 3/8 .058 chain to replace it.

Shoot, even the drive link count is the same, isn't it?


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## kevlar (Aug 24, 2009)

3/8 lo pro is not the same as 3/8,the difference is slight.now with that being said I have seen plenty of saws run the 3/8 sprocket for the 3/8 lo pro application, but not the other way around.


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## TraditionalTool (Aug 24, 2009)

ProMac1K said:


> I thought Picco was a Stihl-exclusive term for 3/8 LP.
> 
> One of my saws came with a LP chain on a 3/8 bar. Granted, it was a .058 bar, but that was the only mismatch. It operated just fine. Just bought a 3/8 .058 chain to replace it.
> 
> Shoot, even the drive link count is the same, isn't it?


I've been told that it is thinner material for the entire chassis.

The gent who taught me how to build with logs told me to avoid it at all costs...:rolleys:


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## MCW (Aug 24, 2009)

Difference between both chains (I'm sure most are aware of this)...





3/8"LP on a standard 3/8" nose sprocket (ie: BAD!)...




Standard 3/8" on a 3/8"LP nose sprocket (ie: BAD!)...




A standard 3/8" rim sprocket will drive a 3/8"LP chain (not sure about spur sprockets though), but best to get the bar for the job. I don't think the standard 3/8" tang will fit a LP sprocket but not sure - bit too deep I think?


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## SawTroll (Aug 24, 2009)

TraditionalTool said:


> Ray,
> 
> That is a confusing thread, they are talking about 3/8, 3/8 lp, and 3/8 picco.
> 
> ...



You got that wrong!
3/8 picco is Stihl lingo for 3/8 lp - no more, no less.

Remember that the pitch is measured at the rivets, not at the contact point between the drivers and the rim. As the contact point is closer to the rivets on the lp/Picco, they need a slightly larger diameter rim to run on.


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## B_Turner (Aug 24, 2009)

I think this thread is making the difference more clear than I've seen before.

I could understand about the sprocket nose issues easily enough, but I think I get the differences between the chains where the tangs fit the drive sprockets a bit better now. 

Next time I have a 3/8 lp drum sprocket off (which will be soon as I'm switching another saw to 1/4) I'll get out a 3/8 floating rim and each chain and really try to see how they each fit each drive.

Thanks.


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## TraditionalTool (Aug 24, 2009)

SawTroll said:


> You got that wrong!
> 3/8 picco is Stihl lingo for 3/8 lp - no more, no less.
> 
> Remember that the pitch is measured at the rivets, not at the contact point between the drivers and the rim. As the contact point is closer to the rivets on the lp/Picco, they need a slightly larger diameter rim to run on.


Troll,

Is it true that the thickness of the wall is thinner on the picco? That is what I have been told.


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## djmercer1 (Aug 24, 2009)

MCW said:


> Difference between both chains (I'm sure most are aware of this)...
> 
> 
> 
> ...



those pics show why my dealer calls standard 3/8, 3/8 large.... without any amount of timer fallers(pulp wood only), most dont need the large chains.... almost impossible to get 404 here....


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## ProMac1K (Aug 24, 2009)

My next thought.....

Do they make a bar that will interchange 3/8LP and 3/8 nose sprockets? I thought my 3/8 bar that had 3/8LP chain on it fit good at the nose. So good that I thought it was a .325 bar and chain, until I recognized .325 for the first time at a dealer.


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## Boogieman142 (Aug 24, 2009)

3/8 lo pro is .365


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## heimannm (Aug 24, 2009)

I am pretty sure you will discover that all 3/8" chain (standard and LP) are really more like .365, the profile of the tooth and the drive link are different as as Troll points out require different configurations of the sprockets. We simply call them 3/8" since it seems close enough.

It may be possible to run a LP chain on a standard drive sprocket and vice versa, I guess I've never tried, at least that I was aware of.

I did find something interesting on one of my old saws with a 7/16" pitch chain and spur sprocket, .404 chain actually fit the sprocket better, correctly in fact. Believe it or not the .404 sprocket would drive the 7/16" (.4375")
pitch chain but I don't suppose it would last very long doing it.

Mark


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## MCW (Aug 25, 2009)

heimannm said:


> I am pretty sure you will discover that all 3/8" chain (standard and LP) are really more like .365, the profile of the tooth and the drive link are different as as Troll points out require different configurations of the sprockets. We simply call them 3/8" since it seems close enough.
> Mark



Thats right Mark, they are both really .365" - I checked this last time with my calipers after you mentioned it as I thought you may be wrong but alas...
I was 
It is the size and shape of the drivelinks that are the reason they're not interchangeable. 
3/8"LP nose sprockets have rounded teeth, standard 3/8" more pointed. Some guys on here have said that they can run standard 3/8" on a 3/8"LP bar but none of the bars I have in stock will interchange.


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## SawTroll (Aug 25, 2009)

Boogieman142 said:


> 3/8 lo pro is .365



No, there just are some that call it that, to differentiate it from regular 3/8", that they call .375.

*In reality the pitch of all chain called 3/8", .375 or .365
is .367*.


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## MCW (Aug 25, 2009)

SawTroll said:


> No, there just are some that call it that, to differentiate it from regular 3/8", that they call .375.
> 
> *In reality the pitch of all chain called 3/8", .375 or .365
> is .367*.



Not fair Sawtroll, I only have a cheap set of calipers and .365" was close enough for me


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## Gypo Logger (Aug 25, 2009)

It's so much less hassle to never mix and match gauge and pitch. Everything I use is 3/8 .050. The only need for smaller pitch is a small saw that won't drive 3/8.
Gypo


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## SawTroll (Aug 25, 2009)

MCW said:


> Not fair Sawtroll, I only have a cheap set of calipers and .365" was close enough for me



Surely, for all practical purposes - but not for the discussion......:jawdrop:


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## B_Turner (Aug 25, 2009)

Yukonsawman said:


> It's so much less hassle to never mix and match gauge and pitch. Everything I use is 3/8 .050. The only need for smaller pitch is a small saw that won't drive 3/8.
> Gypo



Granted. Mostly I wanted to better understand the issues and thanks to all the good info in this thread I think I do more than before.

But I've added a number of small saws lately including a couple small redmaxes that are designed only to do 3/8 lo pro (only sprocket size redmax sells for them). ALthough I'll probably switch them out at least some of the time to 1/4 (aftermarket source for 1/4 drum sprockets), I was thinking of comparing them and my 339 for time with the same lo pro chain and bar.

Kind of would like to esp be able to compare gz4000 and 339 under same conditions. 40cc vs 40cc shootout.


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## Matt Thompson (Jun 26, 2018)

0.375" is simply the fractional equivalent of 3/8" (3÷8=0.375) and it should never be thought of as an indicator of the profile of the chain. Make sure the new chain IS or IS NOT low-profile. If you're not sure, ASK.

I'm looking at a Poulan Pro PR5030 for a third saw to have around so the girls can help with thinning the back yard out, and they list their chain in the manual as 3/8". If that sounds strange for a cheaper saw, that's what I thought. But I just asked Poulan and Jonathan T. replied back that it is, indeed, a full 3/8"×0.050"×70.

Never guess on this stuff, and if you plan on using the trial-and-error method then keep in mind that errors can be fatal. I'm overly-cautious, and I'm not a professional, but I've seen enough accidents and know enough people who are scared to death of chainsaws so I help them out whenever I can. I don't want my neighbor's kids see me, or anyone else, get hit in the face with a busted chain.


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## Brent Nowell (Jun 26, 2018)

SawTroll said:


> No, there just are some that call it that, to differentiate it from regular 3/8", that they call .375.
> 
> *In reality the pitch of all chain called 3/8", .375 or .365
> is .367*.


Holy moly... this makes things confusing, before I read this thread I had no idea there even was .365
Now I just learned that all 3/8 pitch chain is actually .367

So really we should be calling all 3/8 chains 

367/1000 chains to be correct

Lol


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## Brent Nowell (Jun 26, 2018)

Here’s a question, how are the bars and sprockets marked for low profile if they are both called 3/8


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## Franny K (Jun 26, 2018)

Brent Nowell said:


> Holy moly... this makes things confusing, before I read this thread I had no idea there even was .365
> Now I just learned that all 3/8 pitch chain is actually .367
> 
> So really we should be calling all 3/8 chains
> ...


Call it 3/8 not .375. use 1640 drive links per hundred feet in any calculation.

I can tell by looking at a spur or nose sprocket. Stihl rim drive sprockets are marked picco if for that.


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## SawTroll (Jun 27, 2018)

Brent Nowell said:


> Holy moly... this makes things confusing, before I read this thread I had no idea there even was .365
> Now I just learned that all 3/8 pitch chain is actually .367
> 
> So really we should be calling all 3/8 chains
> ...



.367 (or maybe .366) would be most correct for new chain - but calling it 3/8" isn't _that_ bad as "just a name" *provided* nobody is "translating" it to .375 (or calling the lo-pro variant .365, no doubt as they thought it was a "smart" way to tell that it is different - which it isn't when the pitch is about the only thing that is the same).
That train left the station long ago though, due to assorted marketing people. As usual, the marketing people knew too little about the products, and created a mess.


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## SawTroll (Jun 27, 2018)

Franny K said:


> Call it 3/8 not .375. use 1640 drive links per hundred feet in any calculation.
> 
> I can tell by looking at a spur or nose sprocket. *Stihl rim drive sprockets are marked picco if for that*.



Picco, or just P - I have seen both (note "P-7 and "P-8 on the Picco rims to the right in the picture below).

Also note that Picco rims are larger than regular 3/8" (to the left), they have to be to compensate for the lower chassis of Picco/lo-pro chain.


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## Brent Nowell (Jun 27, 2018)

SawTroll said:


> Picco, or just P - I have seen both (note "P-7 and "P-8 on the Picco rims to the right in the picture below).
> 
> Also note that Picco rims are larger than regular 3/8" (to the left), they have to be to compensate for the lower chassis of Picco/lo-pro chain.
> 
> View attachment 660014



Excellent thanks for the clarification, but what about husky standard spur sprockets, how do you know if one is low pro or standard 3/8? Again is the diameter larger on the low pro 3/8?

This is very similar to all the different Cali era for rifles, for example 5.56mm rounds and .223 rounds are virtually the same but case dimensions are slightly different. Both will work in a rifle chambered in .223 but due to case pressures on 5.56 should not be used in a .223 rifle. The opposite is true for 7.62mm and .308


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## NCPT (Jun 27, 2018)

Too....many....numbers....


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## SawTroll (Jun 27, 2018)

Brent Nowell said:


> Excellent thanks for the clarification, but what about husky standard spur sprockets, how do you know if one is low pro or standard 3/8? Again is the diameter larger on the low pro 3/8?
> 
> This is very similar to all the different Cali era for rifles, for example 5.56mm rounds and .223 rounds are virtually the same but case dimensions are slightly different. Both will work in a rifle chambered in .223 but due to case pressures on 5.56 should not be used in a .223 rifle. The opposite is true for 7.62mm and .308



I know of those rifle caliber differences, and the result surely is somewhat similar to the Picco/lo-pro vs. regular 3/8" issue. With the chain it _sort of_ works using Picco chain on a "regular" drive sprocket (the chain runs erratic/sloppy around the rim though), while the other way around isn't really doable at all (at least not with fairly new sprockets and chain, that are within normal production tolerances) - with a badly worn or undersize sprocket and/or a badly stretched chain it _may_ be doable though.

Regarding the Husky spur sprocket I don't know, except that the lo-pro spur _should _have a larger diameter, just like the rims. I have never used a Husky with a spur on it.


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## Grande Dog (Jun 27, 2018)

Howdy,
All Lo Pro spur sprockets that I'm aware of are 6 tooth. If you need a Lo Pro rim with a standard spline http://leftcoastsupplies.com/product/rim-3-8lp-x7-standard-spline-gbf-gbr7l7/
Regards
Gregg


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## PogoInTheWoods (Jun 27, 2018)

Can't help but give this thread a thumbs up for longevity if nothing else. And while I'm at it, here's an FOP for Carlton's LP chain back in the day. Evidently .365 was close enough for them to label it as such..., most likely to simply differentiate between the FOP model numbers and obviously the two 3/8's chain types. ('N' designates LP and 'A' designates normal 3/8's)


​


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## old guy (Jun 27, 2018)

Ok, here are the rims side by side to show the differences


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## SawTroll (Jun 28, 2018)

Grande Dog said:


> Howdy,
> All Lo Pro spur sprockets that I'm aware of are 6 tooth. If you need a Lo Pro rim with a standard spline http://leftcoastsupplies.com/product/rim-3-8lp-x7-standard-spline-gbf-gbr7l7/
> Regards
> Gregg



_Standard_ spline GB Picco rims have been available for some time (in the UK), but this is the first time I see them for sale in the US - and the first time I see them not carrying a "premium" price tag!

What have been totally absent in the market (as far as I have looked) are _small_ spline Picco rims (for Husky saws etc. etc.). The Stihl rims a _mini spline_, and as far as I know only compatible with Stihl saws (as they come, it should be possible, although not easy, to make them fit small spline drums).
I believe Danzco made some pin type small spline ones some years ago, as I have been told so - but I have never seen them listed for sale anywhere.


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## SawTroll (Jun 28, 2018)

PogoInTheWoods said:


> Can't help but give this thread a thumbs up for longevity if nothing else. And while I'm at it, here's an FOP for Carlton's LP chain back in the day. Evidently .365 was close enough for them to label it as such..., most likely to simply differentiate between the FOP model numbers and obviously the two 3/8's chain types. ('N' designates LP and 'A' designates normal 3/8's)
> 
> View attachment 660061
> ​



Yes, I believe Carlton has to carry most of the blame for starting the *very* unfortunate .375 vs. .365 mess. This is just an impression I have though, I obviously don't know everything....


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## PogoInTheWoods (Jun 28, 2018)

old guy said:


> Ok, here are the rims side by side to show the differences



I see the subtle differences in the size of the drive design but they look to be the same diameter by the way you have them held in the pic.

And out of curiosity, what are those?


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## old guy (Jun 28, 2018)

The lo pro is slightly larger diam. If you look at a lo pro bar you will see the blunter points on the wheel where the regular 3/8 wheel has pointy points.
It's been a while since I took those picks but think they were for an 026.
I picked the 026 in trade, it had a 3/8 bar & chain on it but the chain ran very rough no matter what I did, I finally figured out the 3/8p on the drive rim meant 3/8 picco which is Stihls term for lopro, changing to a regular 3/8 rim cured it.
I have run lo pro on reg 3/8 drive & bars, it will work but it ain't right, the other way around however does not work.


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## dsell (Jul 7, 2018)

Here's a 3/8 LP 7 tooth. Good luck finding new ones.


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## Country bumpkin (Jul 7, 2018)

MCW said:


> Difference between both chains (I'm sure most are aware of this)...
> 
> 
> 
> ...


Good examples. That’ll help him.


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## SawTroll (Jul 8, 2018)

.


MCW said:


> Not fair Sawtroll, I only have a cheap set of calipers and .365" was close enough for me



Well, I have later learned that .366 actually is more correct than .367 - but the real point is that it *isn't* .375.

3/8" is acceptable as a "name" on the pitch - while "translating" it to .375 gives the impression of a more accurate number, and isn't acceptable as a designation when it isn't true. If they had called it just .37 (*not *.370 though) instead, it would have been acceptable.


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