Chain not sliding inside the gauge but riding on the top of nose sprocket teeth.

[NAKATA]

Good evening Gents!

I need your expert opinion on the following matter:

Is this gap between the bar`s gauge and the chain on the nose normal or the chain has to be touching and sliding on the gauge?

My opinion is that the chain has to slide on the gauge and not riding on the sprocket teeth as it create too much stress on the sprocket teeth bearing.

See photos bellow!

 

[Franny K]

The drive links fold around the teeth at the nose and if you see sparks it is because it is rubbing. If the first picture has sort of rounded tips after the chain is removed for viewing it is the correct one for 3/8lp but if the tips are kind of pointy that tip is for full sized 3/8.

 

[J D]

The whole point of the sprocket nose is to stop the chain riding on the bar rails. If the chain rides on the bar rails around the tip it has to be a hard nose bar with considerably harder metal... in this situation there is more friction, drag & wear (but no sprocket to get clogged up or fail). In most situations the increase in cutting power that goes along with a sprocket tip is well worth their use, & in the situation that a quality bar would likely outlast the sprocket they are generally replaceable

 

[Matt81]

The sprocket nose is designed to fully support the chain. There should be a gap to prevent extra friction and wear and a slowing down of the chain speed. Over time as the sprocket nose teeth wear down the chain will eventually touch the bar nose. Often you will start to see sparks when this gets bad enough. Time for a new sprocket nose if your bar supports this or a new bar if it does not.

Never had a sprocket nose bearing fail yet from a correctly tightened chain in around 30 years of cutting. It is what they are designed to do after all.

Also the gauge of a bar is the width of the groove where your chain drivers run in. The drivers of the chain must have the same gauge to work properly. Sounds like you are using the word gauge to refer to the gap between the bar nose and the chain.

 

[NAKATA]

Thank you all for your answers!
That's much appreciated!
Apparently I have been wrong, there should be a gap between the chain and the bar on the nose.

Can you give me advice on something else I'm having problem with....
How tight the chain has to be on a 42" milling bar.
If its too tight the chainsaw won't run its like the brake is on, but if I leave it little bit loose it jumps off the bar when I hit the throttle and makes sparks.
I get away with loose chain on 24" bar with 60cc chainsaw but on 42" with 92cc 7hp Husqvarna 592xp it has so much more power that makes a wipping wave on the upper side of the bar with sparks.
Some say the chain has to be 1cm of the bar when pulled with 2 fingers.
Regards!

 

[J D]

Do the drive links slide freely around the bar groove? Does the sprocket spin freely without any play? Is the sprocket worn or damaged? (This can happen very quickly from clamping a mill frame too close to the sprocket). Do the pitch & guage match on bar, chain, & drive rim? Are the rails clear of debris & receiving adequate lubrication?
After you confirm all that, your 1cm when pulled with 2 fingers is about right. Make sure bar tip is raised as you tighten or tension may change when cutting. For most cutting conditions, minimum chain tension should have no visible chain sag of the bottom of the bar. You also don't want the chain so tight you can't lift a couple of drive links clear of the bar rails at the center of the bar (without straining, using just your thumb & forefinger).
Tension can be pretty subjective & is guaged differently for shorter or longer bars.
There's no good reason a 592XP should struggle to pull the chain around a 42" bar so I suspect there is some physical/mechanical issue you need to address

 

[NAKATA]

Do the drive links slide freely around the bar groove? Does the sprocket spin freely without any play? Is the sprocket worn or damaged? (This can happen very quickly from clamping a mill frame too close to the sprocket). Do the pitch & guage match on bar, chain, & drive rim? Are the rails clear of debris & receiving adequate lubrication?

I suspect there is some physical/mechanical issue you need to address

Good afternoon J D !

Thank you for your reply!

Please see the video bellow, this is brand new out of the box GB head, is this play normal?

 

[NAKATA]

Good day to all!

The reason for this enquiry is that I had brand new GB bar head failure on the first day of cutting and I`m trying to find out where the problem is?
Is it operator`s error of the equipment or a warranty claim?

This is the chain of events:
I have been milling for over 3 months now with 60cc 4HP 24" bar chainsaw and "VEVOR" Alaskan mill mainly soft wood with low density like cotton wood and walnut.
After I gained enough experience the next logical step came and upgraded to 92cc 7HP Husqvarna 592XP and 42" 19-SNHL42-50WR ARBOR TECH bar with 1.3mm OREGON 91R chain. ( according to the dealer all those parts are compatible)


After watching:

1. Bedding In Your New Chainsaw Bar Correctly to Ensure Best Longevity​

2.Long bars need regular chain tensioning particularly if you are running lo pro chains.​

I was confident that everything is properly set up before we start!
BTW the bedding was little bit hard as there was paint on the rails of the brand new bar but eventually the chain was able to move freely by hand.

So we start working on!


The chain was getting slack half way trough the first cut as expected and tightening was done only after the end of cutting, as it is very inconvenient to tighten the chain when the chainsaw is upside down.

The problems started on the last log, the chain flew away from the bar and we notice the bar nose sprocket gear was ....missing it was nowhere near to find.


After investigating we notice that the chain is in good condition and there was no metal in the log to be blamed, BTW I did scan each and every log prior to start cutting with a metal detector and there was no metal inside.

The aftermath:
I order spare head, but the new one looks so loose and with so much play I start wonder if this brand is reliable enough?
The other thing is that I notice scoring on the cutting side of the bar,...when the chain got loose it was not sitting inside the rails but riding on the top of the bar, but I checked lubrication after each cutting and the chain was oily on the top and bottom of the bar. (The oil pump adjustment was turned to MAX from the very beginning).


What are your thought about the above?

 

[J D]

GB is generally reliable & considered one of the better manufacturers. Seems like your first tip has failed prematurely & should be replaced under warranty. If something doesn’t feel right with the new tip it's possible they've had a bad batch.
Is your drive rim specifically for 3/8 low pro? A standard 3/8 rim drive is different, won't match your lo-pro setup & will cause issues.
Your setup looks like it could be a bit more ergonomic too... if you raise one end of the log so you're cutting downhill gravity will help a lot. Likewise if the winch is anchored slightly lower you wont be trying to pull the saw up in the cut towards the end of the log. Some sort of triger lock might enable you to position yourself better (I prefer to be more behind the mill, it helps me control feeding more evenly). Looks like you might be applying a bit too much pressure with your winch.
How are you sharpening your chains & what kind of profile are you getting?
There's a heap of good info in the CSmilling101 thread you should check out if you haven't already done so... @BobL has a huge amount of valuable insight on the subject.
With regard specifically to lo-pro @Coralillo Lo Pro might have some more to add

 

[NAKATA]

GB is generally reliable & considered one of the better manufacturers. Seems like your first tip has failed prematurely & should be replaced under warranty. If something doesn’t feel right with the new tip it's possible they've had a bad batch.

The dealer refused to change it under warranty. Head is " consumable" they say.

Is your drive rim specifically for 3/8 low pro? A standard 3/8 rim drive is different, won't match your lo-pro setup & will cause issues.

NO ITS NOT!
The sealer said the standard drivethat the chainsaw comes with is 3/8 and its compatible.
What kind of issues this can cause?

Your setup looks like it could be a bit more ergonomic too... if you raise one end of the log so you're cutting downhill gravity will help a lot.

I agree with you!
I'm still in try and error with this new set up.
Yesterday i repositioned the winch and placed ring nuts to guide the rope horizontally and also small pulley so that the rope doesn't jump off and slackens all the time. Also a steel rod at 45 degrees that anchors on the bottom of the log and the pulley gets attached to it.

Likewise if the winch is anchored slightly lower you wont be trying to pull the saw up in the cut towards the end of the log. Some sort of triger lock might enable you to position yourself better (I prefer to be more behind the mill, it helps me control feeding more evenly). Looks like you might be applying a bit too much pressure with your winch.

That used to be my position with the 24" set up but with the new one I'm a bit scared to stay behind the mill seeing the power and how the chain jumps off the rails my primary instinct dictate me to stay away.
This is my old set up by gravity with 24" bar.

How are you sharpening your chains & what kind of profile are you getting?

With electric grinder EINHELL at 10° but the 42" chain is still brand new sharpened by the dealer. To be honest I wasn't happy with their sharpening (the gullet was almost vertical ) so I cleared the gullet and made it 60° big "C" shape.

There's a heap of good info in the CSmilling101 thread you should check out if you haven't already done so... @BobL has a huge amount of valuable insight on the subject.
With regard specifically to lo-pro @Coralillo Lo Pro might have some more to add

I will definitely check them out!
Thank you for your response and information shared!
Regards

 

[J D]

The dealer refused to change it under warranty. Head is " consumable" they say.

Yes it's a consumable, but it should still work as intended & not fail immediately. If you bought a file & it lost its teeth on the first use it would be faulty just the same. I'd press for a warranty replacement & say you intend to contact GB & complain directly if he still refuses

NO ITS NOT!
The sealer said the standard drivethat the chainsaw comes with is 3/8 and its compatible.
What kind of issues this can cause?

It most definitely isn't.
You can get away with it to a cretain degre on well worn stuff but you are driving the chain with a rim thats too small & will be putting the load unevenly on the drive links... this could cause deformation which could be contributing to your binding. The missmatch will almost certainly be contributing to how hard the chain is to turn by hand. A .404 rim is actually closer & can be turned down to suit. There are a bunch of threads here on the subject, google search generally works better than the site search function... here's one to get you started
https://www.arboristsite.com/threads/3-8-lo-pro-and-3-8-sprocket-differences.107256/

That used to be my position with the 24" set up but with the new one I'm a bit scared to stay behind the mill seeing the power and how the chain jumps off the rails my primary instinct dictate me to stay away.

When it comes to chain breaks while milling, the dangerous place to be is around the tip of the bar or around the underside of the saw if cutting with the top of the bar. Generally speaking the risk of getting whipped with a chain is far less if you are milling than it would be x-cutting as the bar is usually burried & has the mill shroud around the tip

With electric grinder EINHELL at 10° but the 42" chain is still brand new sharpened by the dealer. To be honest I wasn't happy with their sharpening (the gullet was almost vertical ) so I cleared the gullet and made it 60° big "C" shape.

I was under the impression the Oregon 91R was factory ripping chain, so should come from the dealer untouched with the manufacturers profile on it.
You are correct in that ripping chain wants a greater top plate cutting angle or "hook"

 

[Coralillo Lo Pro]

Agreed about GB making quality lo pro bars - never have had an issue remotely like this with my 36" GB lo pro bars. Running the setup on a standard 3/8" drive rim definitely wasn't helping, I'm sure. Dealers usually don't know a thing about running lo pro on saws that size for milling so not surprised you got bad info there. If the GB bar was ordered from Chainsawbars in the UK, then the matching 3/8LP drive rim needs to be ordered from them too. I like their Panther chain better than Oregon 91R, and if you're in Europe, you can probably get Stihl 63PMX at a reasonable price which is by far the best 3/8LP chain to use. It helps to know where you got all your gear from, if everything was from the same place in Bulgaria, or if you got your chain and bar from Chainsawbars and your 592XP from a local dealer in Bulgaria. Chainsawbars is the only place in the world I know that sells lo pro gear that actually knows everything there is to know about lo pro and will almost never steer you wrong.

With an 87cc saw and a 3/8LP drive rim and GB 36" 3/8LP bar, I've never had any issues with stretching my chains all that much when new. My tension on longer bars (36"+) is usually pulling up on the chain midway along the bar on top with two fingers with moderate pressure, and if I can't pull the runner on the link I'm holding completely out of the rail, I call it good. If I can barely get it up out of the rail at all, it's too tight. The whip waving sounds like the chain was catching somewhere, either on incompatible drive rim or maybe a defective nose sprocket.

Also, I'm assuming you got the adapter to fit the 592XP Husqvarna mounting bolts since that model of 42" bar I believe is a Stihl 12mm mount?

 

[NAKATA]

I like their Panther chain better than Oregon 91R, and if you're in Europe, you can probably get Stihl 63PMX at a reasonable price which is by far the best 3/8LP chain to use.

The dealer offered me only two chain types that are compatible and I bought 2pcs or Oregon.
"Attention! Suitable 3/8" LP chains are OREGON 91R or STIHL 3614. The large 3/8" pitch with 1.3mm does not fit - e.g. B. OREGON 72RD"

It helps to know where you got all your gear from, if everything was from the same place in Bulgaria, or if you got your chain and bar from Chainsawbars and your 592XP from a local dealer in Bulgaria.

The chainsaw and the milling gear are from separate dealers, however initially I wanted to run the gear on Husqvarna 555 but the dealer corrected me that this is .325 chainsaw and I bought 592xp then he confirmed that this comes with 3/8 and will fit his products for milling but I need an adapter where the bar conects to the chainsaw. Nothing mentioned for 3/8 LP rim at all.
https://mina-parts.com/product/2529...menyaema-glava-tankorezheshta-za-bichene.html

They have detailed explanation on their website what chains are compatible and which not.

"SNHL mount suitable for Stihl MS 341 - 661 (mount 3003 and Oregon D025). Can also be used with most larger Husqvarna chainsaws (does not fit 3120XP) and Dolmar with adapter 19-006-01."

My tension on longer bars (36"+) is usually pulling up on the chain midway along the bar on top with two fingers with moderate pressure, and if I can't pull the runner on the link I'm holding completely out of the rail, I call it good. If I can barely get it up out of the rail at all, it's too tight.

Same here!

The whip waving sounds like the chain was catching somewhere, either on incompatible drive rim or maybe a defective nose sprocket.

After operating chainsaw for so many years (not milling but bucking and cutting) this felt wrong to me when I saw it on the big bar for milling but didn't know what is causing it.

Also, I'm assuming you got the adapter to fit the 592XP Husqvarna mounting bolts since that model of 42" bar I believe is a Stihl 12mm mount?

Yes, the dealer offered me adapter.

 

[Coralillo Lo Pro]

You sound like you got most everything correct you needed except this lo pro drive rim. https://www.chainsawbars.co.uk/product/gbr7l7-gb-lo-pro-drive-rim-st-internal-3-8-lo-pro-chain/
I think the problem is that GB made this specifically for Chainsawbars in the UK to sell so it's hard to find anywhere else. The GB distributor in the United States told me they were available though when I was thinking of starting a business selling lo pro milling gear. Maybe that website you bought from can get them from GB if they know what to ask for? That little drive rim is the single thing that has kept most people from milling with lo pro. Everything else (chain, bars) isn't hard to find but that drive rim for saws over 60cc is. There's a company in the US that makes them called 6K but they're about $40-50 apiece compared to the GB model that is less than $20.

 

[NAKATA]

You sound like you got most everything correct you needed except this lo pro drive rim. https://www.chainsawbars.co.uk/product/gbr7l7-gb-lo-pro-drive-rim-st-internal-3-8-lo-pro-chain/
I think the problem is that GB made this specifically for Chainsawbars in the UK to sell so it's hard to find anywhere else. The GB distributor in the United States told me they were available though when I was thinking of starting a business selling lo pro milling gear. Maybe that website you bought from can get them from GB if they know what to ask for? That little drive rim is the single thing that has kept most people from milling with lo pro. Everything else (chain, bars) isn't hard to find but that drive rim for saws over 60cc is. There's a company in the US that makes them called 6K but they're about $40-50 apiece compared to the GB model that is less than $20.

Yep, that little small thing!!!!
And that drives me crazy cos it cost so little but its so difficult to get!
Delivery is 3-5 days and shipping cost more that the bloody thing!
My sister lives in the London UK she can buy it and send it in an envelope, but she is currently on a holiday in Peru!

I found out that Chainsawbar.com sell whole kits, but only if I knew earlier!
https://www.chainsawbars.co.uk/product/snhs42-50wr-kit-42107cm-gb-lo-pro-milling-bar-kit/
On the top of that its written here:
"Oregon 91R – Better suited for smaller milling rigs ie. 25″(61cm) and under. Depth gauges seem to be overly high to take as much of a ‘bite’ as the Stihl PMX chain."

Dealer told me 91R will be fine with 42" bar.....
I'm pulling my hairs now!!
I guess the Lord sends all this troubles my way to test my faith!
Regards!

 

[Coralillo Lo Pro]

I feel for you! I was curious about lo pro for years but couldn't assemble a complete setup because I couldn't get the drive rim. It was only when I discovered Chainsawbars (and free fast delivery to the US over $180 or so) that I took the plunge into lo pro and never looked back. It's SO hard to get good information on what you need, so few people know anything about it. The few people in the US who have been milling with it the past 20 years or more have been customizing all their own gear, machining down .404 drive sprockets to the right diameter to match a 3/8LP pattern, using regular bars with sprocketless roller noses, etc. It's still crazy how hard it is to get the right information and right gear from one place, so far Chainsawbars is the only place in the world that has provided it. I might just buy a whole bunch of those drive rims at retail price from Chainsawbars and sell them at a small profit in the US on Ebay just to make them available here. But no one even sells the GB 3/8LP bars here in the US either, nor does Stihl sell Stihl 3614 (63PMX) in the US. At least the lo pro bars and chain are more readily available in Bulgaria than here, but the dealers have to learn they need the 3/8LP drive sprockets too.

 

[NAKATA]

It was only when I discovered Chainsawbars (and free fast delivery to the US over $180 or so) that I took the plunge into lo pro and never looked back.

Same here! Only if I knew them earlier!

It's SO hard to get good information on what you need, so few people know anything about it.

That was big surprise to me as well, even the dealership was not familiar btw I called them today to give them this information and their aswer was:
" Thats new to us, we need to educate ourselves on this matter"

But no one even sells the GB 3/8LP bars here in the US either, nor does Stihl sell Stihl 3614 (63PMX) in the US. At least the lo pro bars and chain are more readily available in Bulgaria than here, but the dealers have to learn they need the 3/8LP drive sprockets too.

It's strange that such a big market like US lacks those lo pro bars and chains, I used to live and work in Orlando FL and amazon and ebay were loaded with parts I needed for my boat and my bike.
Especially in FL where its the Mecca for boating finding parts for my Mercury Force 90HP was easy and cheap.
Ever since I live in Bulgaria and try to find parts for my 1985 Honda Shadow 1100VT (made in Ohio USA) Good luck with that!!! Minimum 2 weeks delivery, tariffs, EU honda dealership programs dont even recognize the VIN of the bike. Its a nightmare!
Anyway...back to milling...atleast now I know what needs to be done and hopefully this will be sorted out one way or another.
This is a video from Chainsawbars.com


The first comment by JoshJohn77 wrap it all!

 

[NAKATA]

 

[Coralillo Lo Pro]

I got one of those big lo pro sprockets that are made by 6K in the US, a 10 tooth sprocket because I wanted to reduce the torque and increase the speed of my big saws. I actually told Rob at Chainsawbars about those sprockets and he started stocking them. I have old 87cc Stihls that are high torque and slow speed, and an MS880 I was going to try a 48" bar on, but worried it had too much torque and would snap chains too easy. But the 10 tooth is too big for the chain to flow right into the tail of the bar, so I haven't used it. Since the 592XP is such a high rpm saw already, there's no need to use any more than the standard inexpensive 7 tooth lo pro drive rim.

I'm from Florida originally, grew up on the Treasure Coast in the town of Stuart, been around boats most of my life. I lived in southern Mexico for ten years and getting parts for my Honda 90 outboards there was impossible, had to ship everything from the US. But I agree, it's really weird to me how backwards the US is on some things about chainsaw milling, I'm really surprised about the things that aren't available here that you can get in Europe. It's usually the other way around, particularly with things like chainsaws.