What causes my chain to stop?

[JimL]

I just picked up an 038Magnum. I put a 18" Stihl .050 guage bar on it. Stuck a 33RS chain on it and called it good. When cutting the chain will just stop. I have to move it on the bar by rubbing it on a log ect. to get it moving again.
I am getting more than enough bar oil, check that first.
Any thoughts? I have 7 other saws and none do this.

 

[tundraotto]

do you have a sprocket nose bar? it may be jamming. are the bar rails in good condition? is the chain gauge correct? is the chain pitch correct? and last but not least: examine your clutch on the saw - it may be done.

 

[Walt Galer]

Howdy,

I've seen this many times, though I would find it surprising on an 038. Usually it is caused by an incorrect pitch part in the power train, such as a .325 sprocket and a 3/8 chain. Remember you have a sprocket in the bar nose, that must be the same pitch as the chain! My experience has been that Stihl's product line seem unusally prone to people making this mistake, but usually on the 029 where Stihl tries to send them out with .325 but most folks want to run 3/8. Really buggers up the drivelink tangs on the brand new chain!

Regards,
Walt Galer

 

[the tree guy]

other things to check.has the chain came off resently?check for bent drive links or mushroomed links.has the bar been pinched lately?check bar rails as well as how clean bar groves.IF it is sprocket nose ,can sprocket be turned by hand?can chain be turn by hand with saw shut off?is chain too tight?has the clutch bearing been greased lately?just afew more things to look at. Dan

 

[Gypo Logger]

Hi Jim, not to worry, I have witnessed your problem on several occasions. When the bar and chain are new and your in a long cut, sawdust at times will bind the chain in the bar, sometimes at the tip, but usually in the bar itself. The quick remedy is to push the bottom of the bar forward against a log and goose the throttle at the same time. This will release the sawdust and get you going again. Always run the saw wide open when cutting and this will happen less often.
John Lambert

 

[treeclimber165]

Geez, that thing must SCREAM! I always ran a 24"-27" on my 038Magnum for 10 years, never could get it to bog. With an 18", it must be kinda like a V-8 powered go-cart!

I agree with the advice you have already gotten here. Either 1)the sprocket is shot, 2)something is buggered up (bar or drive links on chain) or else 3)it's sawdust packing up in the bar from not running full throttle.

 

[JimL]

Treeclimber: Yeah, when the bar isn't froze to the chain it screams.

The sprocket(rim) is brand new 3/8 pitch 7T, the bar is brand new, but was run through a bar rail grinder to true up the factory crooked stihl bar. I double checked and it is a .050 guage 3/8 pitch bar. Clutch is new, drum is new, tachs out at 12,000 rpm muffler not clogged, rakers not filed way down(haven't touched them yet). I haven't thrown the chain on it yet so I am pretty sure the drives are ok.

Think ill pitch the stihl bar and go with an oregon powermatch. Never cared for the stihl bars anyway.

Thanks for all your insight...

 

[Walt Galer]

Howdy,

Thanks for your reply. I'm curious as to why a new bar would be run through a grinder to correct an out-of-flat condition? That may have caused the problem if the service was carelessly done. (It is possible they may have hammered the rails down too tight if the bar was hammer straightened Carelessly). Can you spin the chain freely by hand when mounted on the bar? How about spinning the nose starwheel with the fingers? Will it turn freely? I have seen busted inner race bearing centers on new Stihl laminated bars, caused by overly crushed rivetting ex factory. This makes a hitch in the get-along as you rotate the starwheel.

Try putting the chain on the bar with the bar removed from the saw, and observe the fit of the drivelink tangs in the groove. You should be able to move the chain back and forth freely on both sides of the bar. The chain will "hump up" when it goes through any tight spot. This is part of how you inspect a bar after hammering on it.


Please keep at this until you solve it. We are all curious as heck!

Regards,
Walt Galer

 

[Rick Stafford]

I hope Jim L does reply back as well. This is a strange "happening" and like many others waiting for the answer.That is whats so great about this business, It's almost always something different !!!

 

[JimL]

Originally posted by Walt Galer
Howdy,

Thanks for your reply. I'm curious as to why a new bar would be run through a grinder to correct an out-of-flat condition? That may have caused the problem if the service was carelessly done. (It is possible they may have hammered the rails down too tight if the bar was hammer straightened Carelessly). Can you spin the chain freely by hand when mounted on the bar? How about spinning the nose starwheel with the fingers? Will it turn freely? I have seen busted inner race bearing centers on new Stihl laminated bars, caused by overly crushed rivetting ex factory. This makes a hitch in the get-along as you rotate the starwheel.

Try putting the chain on the bar with the bar removed from the saw, and observe the fit of the drivelink tangs in the groove. You should be able to move the chain back and forth freely on both sides of the bar. The chain will "hump up" when it goes through any tight spot. This is part of how you inspect a bar after hammering on it.


Please keep at this until you solve it. We are all curious as heck!

Regards,
Walt Galer

Go to your local stihl dealer (I work there so it was easy)
Pick up a brand new bar, set it on edge on a completely level surface(I used a chunk of granite), 8 out of 10 stihl bars will lean to one side or another. Thats why I ran it through the grinder to true things up. The chain spins freely on the bar off the saw. I did not run it through the bar rail closer...
Only thing I could think of is I used a 13/64 file instead of my usual 7/32 file.
Heres a pic of my chain

 

[JimL]

Another pic.

 

[Walt Galer]

Howdy Jim,

Yep, you have one of those Stihl laminated/projection-spotwelded bars. The uneven rail levelness is caused by a slight mismated laminate condition, and the lack of a rail polish operation to true up. Is that burrs from your grinding that I am seeing on the rail edge? These bars are ok for consumer use, but you are pushing the upper end! You will be a lot happier with a professional, solid, machined, sprocket nose bar.

Your chain is guite a bit hungry. A might too much hook perhaps, but be that as it may, with that large of saw, I bet that thing is cutting like heck and producing more sawdust than the saw's sawdust cover can clear and get rid of! This is especially true if you cut with the motor on or near the ground while cutting at full tilt in a log. The sawdust all tries to go back into the kerf at the top chain, and the bar and sprocket all load up as others have previously mentioned.

Regard,
Walt Galer

 

[JimL]

What you are seeing that looks like burs is just paint worn off. I will try it with my oregon bar when it gets here...

The chain does have alot of hook to id doesn't it. I thought the same, guess I will go back to my 7/32 files.

 

[Art Martin]

Have you checked if the person that put the loop together might have put the connecting tie strap or straps upside down?
Art Martin

 

[JimL]

I put the loop together.

 

[Walt Galer]

Howdy,

Ok, if there was that much poweder pain buildup, that might explain your problems.

The out of square condition of the rail surfaces, could have just been the run of the paint to the bar edges. This same run of excess paint may also have made the groove too tight, causing your chain stoppage problem. This powder paint is amazingly durable and could prove difficult for the chain to get out of there.

The powder paint is applied by clouding it toward the bar as an electrical charge is put onto the bar to attract it. The bar is then run through a heating oven that melts the paint onto the bar. The result is a very good tight finish, but can be a disaster if too much paint is collected on the bar, or if someone's fingerprint is on the bar. The slightest excuse will rust under the unbreathing paint! Paint build-up in the groove is considered a rather serious defect, for the reasons you have experienced. It is a bit difficult to control at the factory.

Regards,
Walt Galer

 

[Gypo Logger]

Let the chain droop down loose, then goose saw. If all else is at it should be, everything will marry together, then tighten chain and resume cutting. Clean bar groove with putty knife every day.
John