Low Profile and 3/8 standard sprockets

[Crofter]

One is nominally .370, the other .375. Will they clash on spur sprockets but be ok on rim sprockets. Jokers I believe had some info on their drive tangs having a different profile. I have heard lots of argument both ways but have never seen any printed data describing why these chains will or will not intermix. In Glens absence I will ask for some authoritative clarity on this topic Lol.

Frank

 

[Crofter]

Originally posted by RockyJSquirrel
Wit

If you actually do wish for 'authoritative clarity', you wouldn't be asking here. All you get here is opinions.

Aw Rocky what a jaundiced eye with which you view the experts on arboristsite. I just thought that someone here might have already chased it down. You are right though about there sometimes being a big difference between opinions and facts.

Frank

 

[kam]

EVEN IF the lp and 3/8 pitch worked on the same
sprocket, you would have to deal with the difference in bar thickness. The lp bar is thinner
than the 3/8. A lp chain on a 3/8 bar would cut a kerf that is too narrow too give the bar the proper clearance. A 3/8 chain on a lp bar would not have the support under the tie straps, the chain being wider than the bar.

 

[ehp]

OK Crofter what are you up to ? Are you trying to get 1/2 inch on that 365 to show everybody how fast it is

 

[Crofter]

Originally posted by ehp
OK Crofter what are you up to ? Are you trying to get 1/2 inch on that 365 to show everybody how fast it is

EHP;

I got one soaking in Slick 50 / Nevr Dull 32;1

Just sent the following off to Oregons Technical dept.

There is a discussion going on in a chainsaw forum regarding the differences and what technically allows or prevents interchange of Lp and standard 3/8 chain on the same sprockets, rim or spur. There seems to be a lot of misinformation afloat. I really am interested in a "why exactly' type answer if possible.

Thanks in advance for any help you can provide.

Frank Wright

 

[Crofter]

KAM

I have never had my hands on the LP chain or their dedicated bars to see how much difference in thickness. Your points are valid. I am curious about the difference in nominal pitch and whether the sprockets have a definite different profile. Jokers mentioned that there might be interference from the taller tooth with the guide plates etc. around the tail of the bar and sprocket cover.
I am cursed with always wanting to know why!

Frank

 

[Lewis Brander]

To Crofter:

Hey, Crofter, you beat me to it. Have been reading threads on the search forum about sprockets. A lot of information, but not much on the differences between the 2 types. Have checked Oregons site but can't find much info there. Have emailed you and a couple others on this queston and know one seems to have any ansures. Maby your email to Oregon tech. staff will yield some ansures. Will be looking for your reply. Thanks. Lewis.

 

[tony marks]

just my opinion.. but cant see where rim or spur would make a difference.. same specs .. either one.. truth is it will sometimes work,sometime. its why many homeowners have trouble. cause it just will work. so they saw happily along .. wearing everthing out..ive done it.
even a standard bar will work with the narrow kerf.. but not to optimum.
difference not much [sometimes] just enough to no be quite rite. jmo

 

[jokers]

Hi Frank,

I thought it was Rocky that made those points regarding the Lo Pro chain? To be honest, I`ve never examined lp close enough to have those opinions and don`t recall having any technical basis for believing or disbelieving those points. What I don know is that I hate lp chain, does that help any? LOL.

Russ

 

[Crofter]

Jokers; Sorry if I misattributed that to you. Keep gettin you two mixed up. I was trusting to memory and some times I forget I'm getting forgetful !! Maybe we'll hear from Oregon. I ordered a loop just to have a look at it.

Frank

 

[kam]

OK, I just made some measurements on NEW bars and chains.

lp bar .165 in.
3/8 bar .170 in. not as much difference
as I remembered

lp chain .140 in. tie bar width
3/8 chain .165 in.


lp chain .182 in. rivet width
3/8 chain .216 in.

I tried the lp chain on the 3/8 bar, it seems OK.

I tried the #/8 chain on lp bar and it seems OK.

I did not install on a saw to try though.

 

[kam]

It appears manufacturers put lp chains on under 40cc. saws,
.325 on 40-50 cc, 3/8 on over 50 cc.
I'm guessing that 1. it's for safety and longevity
as smaller chains would break on more powerfull
saws. 2. efficiency, small motors can't pull a large (wide kerf) chain.
Large motors cannot utilize their extra power by pulling a small chain
(smaller chips).

 

[Lewis Brander]

3/8 LP vs 3/8 sprockets:

Not considering chain gauge, it appearss that after looking at the oregons site that the 6 and 7 tootn LP sproket is more designed to be used with the 90,91 and 95 series chain. It has a more rounded tooth, which may allow it to be used with the .325 pitch chain and the mini 3/8 pitch chain. The 3/8 LP 6 and7 tooth is used mainly on cheaper. smaller, lower HP or cube saws to help keep up the engine RPM's throughout the cut. Ment for Johnny home owner and occasional use saws.

The 7 and 8 tooth 3/8 spur sprockets are more desinged to work with the regular 3/8 pitch chain and higher cube saws and professional users, from what I can see from the Oregon site. I've have never used rim sprockets so don't know that much about them. Don't believe that many people with the cheaper smaller end saws would be to worried about using or knowing the advantages of the rim sprocket system. JMO. Lewis.

 

[Lewis Brander]

To kam

Looks like we're saying and agreeing on the same thing. Lewis.

 

[Lewis Brander]

To Rocky J.

I also agree with the tire analogy. Lewis.

 

[tony marks]

darin put this in a special safe as itllbe valuable some day.. we all agrre.

 

[Crofter]

.370 must be only an approximation number.

Just got around to trying out a new loop of Carlton .370 Lo Pro chain. Compared to a length of 3/8 there is no difference in pitch. over 20 or more links no accumulated diff. in length. The bottom 1/3 of drive tang is shortened. It runs perfectly on 3/8 rim sprocket. I cleaned the gullet area before putting it on my 260 and it cuts very nice and smooth. The kerf is plenty wide to clear the standard bar. no Prob. there. The 260 could handle slightly lower rakers than the chain came with. It bores and cuts well with the nose. It has no antikickback thingies.

Frank

 

[jokers]

That`s interesting Frank, Thanks for taking the time to try this out and report your findings to us.

Russ

 

[Lewis Brander]

To Crofter: 3/8 LP chain:

Glad to see your comparison. Still have a question. Based on the differences in the drive link shape or design. Do you think that the 3/8 LP would have a tendency to rid higher or try to walk up and walk more out of a spur sprocket as compared to a LP sprocket or rim sprocket, especially under load? Would the LP chain have more of a tendency to wear more on the tip of the spur sprocket teeth and wear out the sprocket faster. I woud think so. The rim sprocket seems like the best choice to use in the case of a higher powered saw. The LP sprockt, 6 or 7 tooth would be the next choice, with the regular spur sprocket coming in last because of the wear that would occur on the outer tips of the tooth, especially during wear in or stretdhing of the chain. JMO. Anyone else have any comments. Lewis.