Seizing nose wheel- but only with a brand new chain

[pioneerguy600]

The only time I ever see nose sprockets in decent shape seizing up over and over is when we are cutting dry Oak but likely dry Ash would be dusty as well. That dust will pack in around the nose sprocket rather quickly and stop it solid. For cutting dusty tree species I use one of my solid Windsor bars and do grease the tip at every fill up of fuel, most time that will get me through tank to tank fill up. Cutting all other tree species we commonly have here is no problem for any of our bars, just the dry oak , green oak does not.

 

[JonnyK28]

The only time I ever see nose sprockets in decent shape seizing up over and over is when we are cutting dry Oak but likely dry Ash would be dusty as well. That dust will pack in around the nose sprocket rather quickly and stop it solid. For cutting dusty tree species I use one of my solid Windsor bars and do grease the tip at every fill up of fuel, most time that will get me through tank to tank fill up. Cutting all other tree species we commonly have here is no problem for any of our bars, just the dry oak , green oak does not.

But the old chain works fine, in any wood even dusty oak and any condition and doesn't seize the nose sprocket!

 

[JonnyK28]

Looking at the last photo of the two chains - which is new? Almost looks like the drive links on the upper chain are a bit longer than the lower chain. Maybe the new chain is clearing more sawdust out of the bar groove and forcing it into the nose? Maybe already answered, but did you clear the junk out of the bar groove? You definitely have a stumper. I respect your dealing with this frustration!

Thanks for all your replies. The top chain is the new one, yes that could possibly be it. We cleaned the gallery (bar groove) every time, but I've never even had to think about that previously, it just self cleans! One time it stopped dead and there was a great wadge of saw chips between the chain and the bar halfway along the top of the bar

 

[pioneerguy600]

But the old chain works fine, in any wood even dusty oak and any condition and doesn't seize the nose sprocket!

What is in the sprocket when you clean it out?

 

[Brufab]

The guiderail groove being packed with debris can throw off the chain some causing issue with the chain and sprocket alignment. Happens to me when cutting dead ash in real cold temps and the nose sprocket either seizes up or gets real hot. Then I have to clean the guide rail slot and squirt alil oil on the sprocket and I'm good to go

 

[calamari]

Might depend on the bar. I can tell you that I rarely grease mine and have never had an issue. In fact, some bars have no provision for greasing. If centrifugal force were that much of an issue, wouldn't the grease be thrown out as well?

Centrifugal force affects either oil or grease but I think the difference is that the grease is being applied at the back of the roller bearing so that centrifugal force shoves it into them while oil in the bar's groove starts out above them and is thrown away.
My Makita came with a bar with no hole for grease like I described in my first post. I have a Homelite that's 30 years old that has a provision for grease that I don't recall ever taking advantage of. It has been horribly abused over the years and the nose sprocket still turns freely but it also moves in and out noticeably too. Never seized like the OP describes.
Is that nose replaceable? I think I see a dividing line and two rivets. Doing that should be cheaper if the bar itself is still good.

 

[HumBurner]

1) could be shadow, but it looks like you have one or more depth gauges that are WAAAAAY too low for the tooth.

It also doesn't look like the teeth are sharpened completely.


2) how much side to side play is there in the bar sprocket? Are all the teeth still visible above the bar where they should be?


If the chain and depths are as far off as they look, and the sprocket is worn and has slop, it sounds like you have excess heat and bar/tang/link wear combining with a sprocket that has some wiggle.


Sounds like a sure recipe for seizure.

Also kind of looks like you may have a thin but consistent bur running along the bar.

Remove any burs and dress the rails flat/level with each other.

 

[kenmbz]

This did happen to me cutting dead ash, the rotted wood would get into the nose on my 20" bar and become sludge with the oil and lock the nose up.
Did not happen on green wood, or older dead trees.
It took a lot of work to clean out that stuff in the nose. Happened less often with my 18" bar, so though ti was oiling, but put it into the same part rotted tree and walla , nose clogged.

These trees were pretty solid but dead. Only wet a bit in so not visible until bucked. Some dusty wood and then some green wood. Seems like the combo of the three was what was clogging the nose.

Use the saw on a lot of other trees and never clogged.

 

[JonnyK28]

What is in the sprocket when you clean it out?

A wood chip or two otherwise nothing visibly stuck

 

[JonnyK28]

1) could be shadow, but it looks like you have one or more depth gauges that are WAAAAAY too low for the tooth.

It also doesn't look like the teeth are sharpened completely.


2) how much side to side play is there in the bar sprocket? Are all the teeth still visible above the bar where they should be?


If the chain and depths are as far off as they look, and the sprocket is worn and has slop, it sounds like you have excess heat and bar/tang/link wear combining with a sprocket that has some wiggle.


Sounds like a sure recipe for seizure.

Also kind of looks like you may have a thin but consistent bur running along the bar.

Remove any burs and dress the rails flat/level with each other.

I think the depth gauges are fine, in the picture the chain isnt straight so makes them look out.
No play in the sprocket and the teeth are still visible above the bar, see original picture. And even if the sprocket was worn, it doesn't necessarily explain why the old chain doesnt make the sprocket seize.
Cheers

 

[JonnyK28]

None of the wood we cut is dusty. It was green, solid oak, but happens in any wood, even bone dry sound ash that has been dry-seasoned for 6 years.

 

[HumBurner]

In the photo of the chain, it doesn't seem like they are. Some are round, some are pointed.

I can also see the bottom right cutter has almost no hook and looks like the top plate is rounded off.

As far as the old chain vs. new, the wear patterns match on the old chain, with thr old sprocket and how the bar rails and sprocket currently are.

The new does not match those wear patterns, and definitely could exacerbate any of those issues.


Did you check the needle bearing as was suggested? If one or more roller-pins are missing, it could allow the sprocket to move off track.

 

[bwalker]

I havent greased a bar in years and Stihl bars don't even come with a grease hole.
Red oak and ash will lock up the sprocket from be packed with fines. If the sprocket was truly seized you wouldn't get it unstuck in most cases and if you did it wouldn't last long before the tip came apart completely.

 

[fishdrivel]

The guiderail groove being packed with debris can throw off the chain some causing issue with the chain and sprocket alignment. Happens to me when cutting dead ash in real cold temps and the nose sprocket either seizes up or gets real hot. Then I have to clean the guide rail slot and squirt alil oil on the sprocket and I'm good to go

The packed debris build-up also slows/prevents the flow of oil from the oil port to the rest of the bar.

 

[PV Hiker]

Your old chain and bar have worn together over time so they work. Take a new chain the drive links are not worn down, so are longer and wider. The picture of the two chains show the new one's drive links showing some wear from the sprocket and bar.

As you are cutting at first there is tight clearances and seems to work but while cutting heat is generated and you loose that acceptable clearances and get seizure. After letting the bar cool I wonder if you would be able to spine it around

I would take a good look at the bar and possible just replace it along with a new sprocket and chain. Sort of starting over with new. Sometimes stuff just wears out, nose bearings become defective with wear, etc. Take it as maintenance fees and move forward.

Just a opinion....

 

[PV Hiker]

By the way post 4 and post 6 you show two different bars. one has 4 rivets and the other 5.

 

[PowerSharp Eng]

Interesting problem. Bar run with old chain and no problems, switch to a new factory ground chain and there is a problem with the nose sprocket/bar grooves jamming.
Had a few complaints with the same issue. Got the bars back and found the bar grooves and sprocket jammed with chips. The picture will show even gaps between chip packs, that's where the drive links were. Tightly compressed little bundles of chips. The picture of the nose sprocket shows the chip size. Elongated chips packed into the nose, not bug dust.

Looking into why the chips are not being exhausted from the drive links as they exit at the tail of the bar. They are being recirculated around and around getting packed tighter and forced into the nose sprocket.

JohnyK28, did your bar have similar size of chips packed into the grooves and nose sprocket.

 

[Franny K]

It looks like the drive links are banged up a bit (what few are visible). Dit you or the operator derail the chain in the first 20 minutes? Perhaps chips off the drive link get into the bearing? I would suggest using a fine flat file and make sure no burrs or the like are on the 20-minute problem chain and try again.
The length of the cutters and the lack of paint on the bar are puzzling. As like noted different bars in the various pictures.

 

[PowerSharp Eng]

The bars I reviewed were new and so were the chains.

 

[Franny K]

I see side wear on the nose sprocket like running a .058" chain on a .063" bar.
What is the gauge of the bar?
What is the gauge of the chain?

I noticed a notch on one nose tooth as well. I would think Husqvarna 435, Husqvarna logo on chain, 33 number on drive link, would mean this is the SP33G chain which is NK .325. (0.050 gauge) Not sure about a dedicated NK bar with 5 rivets though. All my NK .325 bars have 10 tooth noses which I think the ones in post 4 look like. My Oregon Pro lite bars in both 0.050 and 0.058 are 12 tooth noses.

Post 6 as I said before is puzzling the chain is more worn at the sliding surfaces than that in post 4.

I would recommend using oil after using aerosol brake fluid, before mounting the chain.