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When to change chain sprockets?

Started by Great Big, February 22, 2009, 07:36:58 PM

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Great Big

On my Stihl 029 the star sprocket is beginning to devolop a little groove on each tooth.  I know this is a sign of wear, but how do you know when to replace it?   
Brandes Farm Trophy Whitetails Est. 1999
Managing for Quality Whitetails in Southeast Ohio

tyb525

Most people replace it every couple chains they go through I think.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

Troutfisher

I'll change them when I can feel the groove with my thumbnail. The first sign of wear is visual, you can see the groove starting to develop. Once I can feel the wear I'll change it. Spur or rim, don't matter.

ErikC

  I get way more time than that. They seem to keep on working fine for a long time after you can see, and feel the wear.
Peterson 8" with 33' tracks, JCB 1550 4x4 loader backhoe, several stihl chainsaws

Great Big

OK then, I'm overdue.  I can EASILY feel the groove with my nail.    What happens if you continue to run the saw with a bad sprocket?
Brandes Farm Trophy Whitetails Est. 1999
Managing for Quality Whitetails in Southeast Ohio

beenthere

Sprockets and chains will try to reach an equilibrium...so to speak. A new chain on a worn sprocket will cause extra wear on both. Like a dual tire, with one larger than the other.

It is the reason I buy one sprocket and two chains. Alternate the two chains until the cutting teeth are "gone", and then replace everything.

Not always possible to keep that up with just two chains, but it is more the theory behind it that makes it the plan.  :)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

ErikC

  I guess sharpening chains a lot and viewing them as throw away items, I just don't think it will be worth replacing sprockets all the time, because the chain will be out of cutters before the driver wear is an issue anyway. Even then, it will need done from time to time.
Peterson 8" with 33' tracks, JCB 1550 4x4 loader backhoe, several stihl chainsaws

Corley5

When the sprocket strips I change it  :)
Burnt Gunpowder is the Smell Of Freedom

semologger


Rocky_J

In my opinion some people change sprockets too often and others seem to never change them at all until they wear clean through. A worn sprocket will rob power from the chain. When the sprocket is worn to the point where you have a hard time tensioning the chain (moving the chain a little will make it either too tight or too loose) then you are probably due for a sprocket. It's hard to recommend replacing the sprocket after so many chains because some people can file a chain and can use one chain for a long time, while others end up replacing a chain after a few failed attempts at sharpening. Others swap out chains instead of filing on the saw.

I've never counted, but I'm going to guess that a sprocket would be due for replacement after about 50 tanks of fuel. Some Oregon rim sprockets have cross hatches cut in them as wear indicators. When the wear is deep enough for the cross hatch to disappear then you're due for a new sprocket.

I also will usually replace the sprocket when I replace a worn out bar. If the bar is shot then the sprocket is too. No sense putting a new chain on a new bar with an old worn out sprocket.

woodburner

I'm with Rocky_J. A chainsaw is a very dangerous thing when it is not properly maintained and not changing the sprocket with at least 3 chains is not maintaining properly.

L. Willey

 Most sprockets have a little horizantal line on each side of the driver holes of the sprocket. When the drive holes touch the horizantal lines, the sprocket is supposed to be worn out.
i usually run them longer than that though.

Red 93 L1 #3383

Friday one of our Foresters came in complaining that the chain on the MS200T started jumping.  Took the side cover off and saw that the sprocket was way overdue.  A quick trip over to the Stihl dealer and the saw is ready to go for Monday.
Stihl's: 2-064AV's, 020T, MS 310
'93 Ford F-150 Lightning, '94 F-150 4x4, '92 F-150 4x4 '80 F-150 EFI 7.5L, '04 Expedition (Wife's)

Kevin


rebocardo

A decent amount of visible wear or where I can see a depression. Or whenever I buy a new bar or a large amount of chains (3 or more), I kept the used one for a backup.  I have bought used chain saws where the main problem was a destroyed sprocket and $3 later I was good to go :-)


sbhooper

This is why these forums are so great.  I haven't given the sprockets on my Huskies much attention and all is going well, BUT I am sure at least the older saw needs the sprocket replaced.  Is there anywhere online where you can get instructions on how to do this and the tools needed?  I would like not having to take it to a dealer to do this job. 
My woods crew:

MS 361
MS 260
Husky 257
Husky 359

656 International w/grapple
Kawasaki Mule
Huskee 22 ton splitter


sbhooper

Thanks!  All I need to do now is figure out the tools. It looks like an easy job once you get the clutch off.
My woods crew:

MS 361
MS 260
Husky 257
Husky 359

656 International w/grapple
Kawasaki Mule
Huskee 22 ton splitter

Rocky_J

Just a piston stop (or some starter cord to stuff into the spark plug hole- don't get it caught in the ports), then spin the clutch off the crankshaft. It is left hand threads so you need to spin it counterclockwise.

Most clutch assemblies have a hex cast in the middle to use a wrench for removal. Some Husky clutches do not have a place for a wrench but there will be a small notch where you can place a prydriver and smack it with a hammer to spin off the clutch.

John Mc

Quote from: Rocky_J on March 01, 2009, 12:39:42 PM
It is left hand threads so you need to spin it counterclockwise.

Rocky - I think you meant "It is left hand threads so you need to spin it clockwise" (to get it off)

John Mc
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

Rocky_J

Thanks John, you're correct. Good catch! I'd hate for my mistake to cause somebody to mess up their saw.   :-\

semologger

I stand corected on this topic. I had a sprocket go bad on my saw here awile back and i replaced it. I replaced it and the bar/chain. Friday the tip on the bar went out. It was a cheaper bar/chain combo. Well that wont happen again. I put the them on today, the sproket was pretty much shot. I ran it about half a minute and it started sliping. Good thing i ran it today know i know in the morning to pick up a new sproket before i get to the woods. I would of been mad to get to the woods and this happen.

Dave Shepard

I've given up on using prydrivers, they never seem to be the right tool. All I use now are screwchisels. 8)
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

sbhooper

Is there somewhere that you can buy an actual piston stop?
My woods crew:

MS 361
MS 260
Husky 257
Husky 359

656 International w/grapple
Kawasaki Mule
Huskee 22 ton splitter

Rocky_J

Any small engine shop or equipment dealer should have them. I have a few, they come with every new Stihl saw I've purchased.

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