Jammed bar sprocket

MrDiesel

Hi All,

Im hoping someone can give me some insight on how to fix a jammed nose sprocked on two bars i have. Both are Stihl rollomatic. I was cutting stringy barks and the nose sproket is full of s**t to the point where i cant even move it with a screw driver.

I have tried oil, wd40, lanolin but it doesnt seem to be loosening the fibourous s**t in the tip.

Any ideas would be great

Eric Frei

Stringy's!

Once I soaked in petrol for a few days, that made no difference either.

Then I picked at it etc but in use it superheated and went blue and crapped itself.

Maybe an oxy and heat it up to the point that the crap burns and comes out as soot!?

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Jeff Darby

Try using a light oil on the tip and taping in the reverse of direction of rotation when in use. Think about it if it is micro strands of stringy bark causing the seizure you need to try and unwrap the strands of bark cleaning it out as you go.

I think the oxy idea is a good one but could remove the metal properties of the bar defeating the purpose.

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Eric Frei

According to this site wood chars and burns between 120C and 260C.

Now a higher carbon steel doesn't temper a real lot at those temperatures.

The heat to be applied at the bearing, that is where the fibres are trapped, avoid heating the rail guides.

I think heat and slow rotation would help. Heat it and try turning it. The unwrapping doesn't always work, that's what people try first but the bearing is choked. As it starts to bind people instinctively get the chain caught on the edge of something and pull backwards trying to rotate the chain backwards. It might get going but things get tight again with use ..... eventually the nose binds up so bad that it's locked solid.

Heating may not be the answer, but knowing how hot to get it without softening is wise.

I have thrown many bars out because of this, and the cheaper bars didn't last long. Sugar palms with their black mesh take their toll and I have chucked bars out. Maybe the answer is bullnose or sprocketless nose bars. I do not cut stringybark or sugar palms often anymore but pricing in a new bar could be wise.

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Jeff Darby

lol...flashback to when I was studying metallurgy...but then again you probably you touched on it as well with your machining background.

I am not familiar with the type of bearing inside the nose of the bar, if it is a bearing of typical construction this would be the touchy part of the heating process maybe a heat crayon could help in not letting you heat it up to much?

I would not waste to much time in trying to reclaim it as the price of replacement might negate the effort.

__________________

Member: Australian Tree Association

Join the Australian Tree Association...Have your voice heard !

Arboriculture, A life long study for some, a passing phase for others

© Jeffrey J Darby 2011

MrDiesel

Thanks guys,

Im going to try warming up the bearing on the bar that is chocked up solid, Its a 35" bar of my 66 so im not real keen to chuck it without trying it.

Tony Knight

I cut stringy's a fair bit, it ocasionally happens and in my case I put it down to a chain blunting off or guides need lowering (finer, softer chips and dust). I found that while hot if I apply some weight and drag the saw back towards me across the log it usually frees up enough to rotate, I then have a cuppa, sharpen the chain and reverse the bar, Startup and goose the saw a few times to wind the crap out and I'm done until evening when I'll pay it a little more attention.

Good luck

Tony

Joshua Rugg

palm dust is the worst to get gummed up in your sprocket! i use a mini screw driver and regularly scrape the bar rails down and dig in the sprocket area. it pulls out allot of crap.

__________________
Stihl
MS192T 14"
MS200T 16"
MS261 16"
MS440 25"

Husqvarna 359 20"
394XP 32"

Poulan P3314 14" ( new hire/groundy saw)

Drouin Tree Service

Soak in diesel

__________________

Drouin Tree Services | Excavator Hire - Drouin and SE Gippsland | Landclearing Melbourne

Joshua Rugg

in A lopas case soak it in diesel and then light it on fire!!

__________________
Stihl
MS192T 14"
MS200T 16"
MS261 16"
MS440 25"

Husqvarna 359 20"
394XP 32"

Poulan P3314 14" ( new hire/groundy saw)

Drouin Tree Service

Thats what sump oil and old tyres are for lol just joking i would never do that

__________________

Drouin Tree Services | Excavator Hire - Drouin and SE Gippsland | Landclearing Melbourne

Eric Frei

Once I got it partially turning, the 44 engine could spin the chain so I revved it etc spraying WD40 like no tomorrow, went blue around the bearing, then a few minutes later it spat the sprocket, stuffed.

For those who have not experienced it, a fully loaded locked bearing you don't know how bad it is.

Replace-able noses for bars .... I've never bought one and never tried fitting one, no shop has taken up the task either and all just sell you a new bar.

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NevC

When it first jams, turn blade over so sprocket turns in opposite direction to fibre clog. If still no go, soak in diesel and try with bar still reversed. Maybe try tapping before reinstalling.

Stringy is the most common wood around here. Never had to resort to burning clog yet.

Drouin Tree Service

I get new noses quite a bit takes them 2 minutes to do.

__________________

Drouin Tree Services | Excavator Hire - Drouin and SE Gippsland | Landclearing Melbourne

Joshua Rugg

just buy yourself a rivet gun and learn to set rivets. its not really that hard. then you can buy a bunch of replaceable nose sprockets and replace when needed. less down time because of cleaning and repair mean more time working
here in the states we dont use hard nose bars over 20".

__________________
Stihl
MS192T 14"
MS200T 16"
MS261 16"
MS440 25"

Husqvarna 359 20"
394XP 32"

Poulan P3314 14" ( new hire/groundy saw)