3/8LP chain on 3/8 rim sprockets?

[IllinoisJim]

A bit of background: Have a Husky 36 with 16" bar. Pretty good for most of what I need to do but a bit bigger saw would be nice once in a while. Really can't justify another saw right now.

So I got a 20" bar and chain. It has narrower teeth which helps reduce the load a bit and seems to work well. pitch is .325. While I was at it I went to a rim sprocket system so got a .325 rim and a .375 rim to switch back and forth. I had a bit of trouble getting a standard loop of chain on the 16" bar due to the bigger sprocket but I was able to get it on and figured the chain would stretch a bit so no real problem. I have run it some - the chain doesn't seem to ride smoothly around the sprocket. I looked at the fit of chain to sprocket and it seemed to fit reasonably well - the chain links are very slightly up off the outside of the rim which may be the issue...

It works but just doesn't seem quite right. Got the stuff from Baileys. Chain is Woodsman Pro WPL 16 30LP56
Rim sprocket is RSM3757 (marked Jak Max 3/8-7) ( I think - I did end up with some sprockets with the wrong spline size and didn't take everything apart to check this)

I have some Oregon chain that I could try. Looking for advice. Thanks!

 

[Mad Professor]

Stihl makes different sprockets for regular 3/8 and their 3/8 picco, the latter is = to 3/8 low pro.

They also have different sprocket tip bars for 3/8 picco.

 

[SawTroll]

Don't do it!

The chain chassis is different, even though the pitch is the same (.367").




Also, 20" and .325 may be a bit much for that little saw.

 

[IllinoisJim]

The bar is made for lp chain so no issue with the tip sprocket. The question is about the drive sprocket. Don't think I made that clear before....

I thought about going to .325 for both the long and short bar but figured I would stay with 3/8LP for the standard bar. Maybe that wasn't such a good choice...

 

[SawTroll]

The bar is made for lp chain so no issue with the tip sprocket. The question is about the drive sprocket. Don't think I made that clear before....

...

I "read" you that way.....

 

[Modifiedmark]

Sounds like your trying to reinvent the wheel.

That saw came with 3/8's lp for a reason. That is because its probably best that way.

It's only a 36cc saw. Sounds like you need a bigger one.

 

[mtngun]

The bar is made for lp chain so no issue with the tip sprocket. The question is about the drive sprocket. Don't think I made that clear before....

I thought about going to .325 for both the long and short bar but figured I would stay with 3/8LP for the standard bar. Maybe that wasn't such a good choice...

I use LP on a standard 3/8" rim drive sprocket and it fits just fine. Several other CSM'ers do the same. No problem.

3/8 LP is NOT the same as Stihl/Logosol Picco and does NOT use the same sprockets.

Mucho information on this thread:
http://www.arboristsite.com/showthread.php?t=121746&highlight=lo-pro

Please post a picture of your LP chain wrapped around your 3/8 sprocket, like this:

 

[SawTroll]

A couple of facts;

Remember that the pitch is measured at the centre of the rivets, not where it contacts the rim.

The LP rim needs to have a slightly larger diameter than the std one, as there is less distance between the centre of the rivets and the bottom of the tie-straps/cutters.

Also, the different shape and size of the drive tangs may be a factor, but not regarding the outside diameter.

On the other side, it also is a fact that some run LP chain on std rims, and report that it works - but then some people also run very worn rims (= less diameter), and notise nothing wrong before they disintegrate........:jawdrop:

Logosol/Stihl offer only spur sprockets for Picco ripping chain over here.

 

[SawTroll]

I use LP on a standard 3/8" rim drive sprocket and it fits just fine. Several other CSM'ers do the same. No problem.

3/8 LP is NOT the same as Stihl/Logosol Picco and does NOT use the same sprockets.

Mucho information on this thread:
http://www.arboristsite.com/showthread.php?t=121746&highlight=lo-pro

Please post a picture of your LP chain wrapped around your 3/8 sprocket, like this:

You need a picture of it under load to prove anything........

Also take a close look at 5 o'clock in your picture.

 

[pgg]

Everyone should know by now that 3/8 lo pro chain doesn't match 3/8 reg bar tips. End of story there.

The 3/8 lo pro chain does work with 3/8 reg drive sprockets but the match isn't PERFECT. For backyard Joe, 3/8 lo pro chain on 3/8 reg drive sprockets isn't really a problem, but for a pro using the saw constantly, the 3/8 lo pro chain & 3/8 reg drive sprocket combo is no good. The sprocket wears too fast and the chain stretches too fast.

 

[SawTroll]

Everyone should know by now that 3/8 lo pro chain doesn't match 3/8 reg bar tips. End of story there.

The 3/8 lo pro chain does work with 3/8 reg drive sprockets but the match isn't PERFECT. For backyard Joe, 3/8 lo pro chain on 3/8 reg drive sprockets isn't really a problem, but for a pro using the saw constantly, the 3/8 lo pro chain & 3/8 reg drive sprocket combo is no good. The sprocket wears too fast and the chain stretches too fast.

:agree2:

...but there is a GB 7-pin LP one that will fit (GBGBJ7S7 according to the info I have) - but 7-pin 3/8" LP may be a bit much on the Husky 36.

Bottom line to the OP; Get a larger saw!

 

[IllinoisJim]

It looks like there is a lot of debate about this (if LP chain works on regular sprockets and such like). But my experience says it doesn't work, at least with the particular parts I have. It turns but not smoothly and I bet it will wear like crazy. Since I don't think I can find a LP rim sprocket it sounds like I need to get a standard sprocket. Thought I had checked this with Baileys when I ordered the parts but it has been a while so I can't be sure...

 

[Brmorgan]

I dunno, I've said it a few times in both the chainsaw and milling forums, I have a 3/8" Oregon LP chain on a standard 25" Stihl .050 bar and standard 7- or 8-pin rims on my big 660, and that setup has cut a few thousand board feet of lumber with no incident so far. Does it stretch more and wear faster? Of course. But as long as everything is kept well maintained and lubed, I can't imagine it being dangerous or damaging to anything. But that's just my experience with it. I won't quit using it anytime soon, that's for sure - it cuts so much faster than standard 3/8" on the mill.

 

[SawTroll]

It looks like there is a lot of debate about this (if LP chain works on regular sprockets and such like). But my experience says it doesn't work, at least with the particular parts I have. It turns but not smoothly and I bet it will wear like crazy. Since I don't think I can find a LP rim sprocket it sounds like I need to get a standard sprocket. Thought I had checked this with Baileys when I ordered the parts but it has been a while so I can't be sure...

Sounds like you are finding some facts - you will learn more if you stay on here....:biggrinbounce2:

 

[mtngun]

You need a picture of it under load to prove anything........

Uh, what am I supposed to do, machine a transparent clutch cover so I can take a picture of the drive sprocket while the saw is running ?:hmm3grin2orange:

It fits fine. Now perhaps the OP's chain/sprocket combo is different, but until he posts a picture, I can only go by what I have seen with my own eyes.

 

[Father Skim]

Everyone should know by now that 3/8 lo pro chain doesn't match 3/8 reg bar tips. End of story there.

The 3/8 lo pro chain does work with 3/8 reg drive sprockets but the match isn't PERFECT. For backyard Joe, 3/8 lo pro chain on 3/8 reg drive sprockets isn't really a problem, but for a pro using the saw constantly, the 3/8 lo pro chain & 3/8 reg drive sprocket combo is no good. The sprocket wears too fast and the chain stretches too fast.

I think I understand the fit issue pretty well. I'm not sure I understand the "stretch" thing well enough. Why would a rim make a chain stretch?
Father

 

[volks-man]

Uh, what am I supposed to do, machine a transparent clutch cover so I can take a picture of the drive sprocket while the saw is running ?:hmm3grin2orange:

It fits fine. Now perhaps the OP's chain/sprocket combo is different, but until he posts a picture, I can only go by what I have seen with my own eyes.

troll is right.
the tang at 4 o'clock is on the edge of not riding right and the link at 5 o'clock is riding up out of the sprocket.

 

[Brmorgan]

I think I understand the fit issue pretty well. I'm not sure I understand the "stretch" thing well enough. Why would a rim make a chain stretch?
Father

The streching issue I (and other millers) experience is that the components of the LP chain - drivers, rivets, tie straps etc. - are smaller and thus don't take the wear and tear as well. Milling heats up a chain even more than general firewood/limbing use, and since heat causes expansion, the chain stretches worse. Combine this with running the chain on a 90cc+ powerhead instead of <50cc as recommended for that chain, and it can become an issue. Still worth using it though IMO.

I can't say whether the standard sprockets would cause extra wear for sure; going by mtngun's nose sprocket picture I could see the argument for that; however it fits the sprocket on my Stihl bar just fine, so I think it's a case-by-case matter. As for the drive sprocket, I'll concede that it might wear the LP chain's smaller drivers prematurely, but the reason there's a buckling at ~5:30 in that photo is that the chain is being wrapped much more tightly around the sprocket than it ever would be during use. The chain would never wrap around more than the rear half of the sprocket; bar heels are pretty much always wider than the sprocket to begin with.

 

[SawTroll]

troll is right.
the tang at 4 o'clock is on the edge of not riding right and the link at 5 o'clock is riding up out of the sprocket.

''Someone" said I always am! :agree2::yourock:

 

[mtngun]

troll is right.
the tang at 4 o'clock is on the edge of not riding right and the link at 5 o'clock is riding up out of the sprocket.

That's just the way the chain is laying, because it is not pulled taut against the sprocket.

Bear in mind that under normal running conditions only 3 - 4 drive links will be in contact with the sprocket. I only wrapped the chain all the way around the sprocket to illustrate the worst case.

Here's another view of the same chain and sprocket. Once again, the slight gap at 7 o'clock is simply due to the way the chain is laying and not for lack of fit, and once again, it wouldn't matter in real life where only 3 - 4 drive links are actually engaging the sprocket, and once again, it's possible that the OP has some weird combo that is an exception to the rule.