Gauging Bar Groove Wear?

[SteveSr]

Hello,

I have a simple question but from my reading of this Forum it doesn't have a simple answer. Assuming that the bar rails are not splayed open is there a simple measurement that can tell when a bar groove is worn too wide to re-use and the bar should be replaced? The measuring tools at my disposal are standard feeler gauges and a dial caliper.

Thanks,

Steve

 

[redoakneck]

If it cuts crooked with a new chain it is too worn. If it is 50 gauge, try 058 gauge. If it is 058 try 063, if it is 063, make a big knife out of it

 

[old-cat]

Bar groove clearance varies widely between different bars. My 28" STIHL light bar seems worn out when it's brand new! I forgot what the numbers are.
The bar will wear far more on the rails than the groove. So you need to measure how much clearance the drivers have in the bottom of the groove. I wouldn't even bother with the width part.

 

[SteveSr]

Bar groove clearance varies widely between different bars. My 28" STIHL light bar seems worn out when it's brand new! I forgot what the numbers are.
The bar will wear far more on the rails than the groove. So you need to measure how much clearance the drivers have in the bottom of the groove. I wouldn't even bother with the width part.

Interesting point about width wear being insignificant to top wear. This may be true with a bar that is getting proper oil. The bar that I am currently looking at came off of a saw with a supposed oil problem which is why I am interested in bar groove width.

 

[Franny K]

Wouldn't the simple way be to put a new chain around the bar and then try and twist the cutters sideways?

Why not use the feeler gagues make a stack that fits in all the way to the bottom then see how much more can be stuffed in near the top or make another stack for the top.

What is too worn for cutting through knots on an angle might work well enough just cutting at 90 degrees to the stem.

 

[Franny K]

If it cuts crooked with a new chain it is too worn. If it is 50 gauge, try 058 gauge. If it is 058 try 063, if it is 063, make a big knife out of it

But post 1 only asks to assume the rails are not splayed they may have worn different.

 

[Philbert]

A simple way to test the 'wear' in your bar groove is with a straight edge. If the grooves have too much slop in them, a straight edge held against cutters on the top and bottom will touch the side of the bar. Try this with a new chain, to make sure that the wear is in the bar groove and not the drive links.


The nose sprocket of a bar can also wear out long before this. If the side plates of the chain are riding on the guide rails, instead of on the bearings, the sprocket should be replaced.


In either case, you can continue to use the bar if the performance is acceptable to you, but they would both be considered 'worn' past the recommended service life.

Philbert

 

[SteveSr]

Well, I took my own advice and went out and measured everything. The drivers on a new chain measure in at .062" The bar groove width measures with a caliper at .075-.080". So the clearance (slop) is about .013-.018". Are there any bar specs that would set a limit to this?

Thanks,

Steve

 

[SteveSr]

A simple way to test the 'wear' in your bar groove is with a straight edge. If the grooves have too much slop in them, a straight edge held against cutters on the top and bottom will touch the side of the bar. Try this with a new chain, to make sure that the wear is in the bar groove and not the drive links.

View attachment 382114
The nose sprocket of a bar can also wear out long before this. If the side plates of the chain are riding on the guide rails, instead of on the bearings, the sprocket should be replaced.
View attachment 382115

In either case, you can continue to use the bar if the performance is acceptable to you, but they would both be considered 'worn' past the recommended service life.

Philbert

Great information! You are sending me to the garage again this evening!

BTW, Where did you get these excellent pictures! I would like to archive the original of these and see if there is more where they came from.

 

[Philbert]

BTW, Where did you get these excellent pictures!

Probably originated in an Oregon technical document somewhere. I might have pulled them from a USFS document, or Madsen's site, or . . .

Philbert

 

[SteveSr]

A simple way to test the 'wear' in your bar groove is with a straight edge. If the grooves have too much slop in them, a straight edge held against cutters on the top and bottom will touch the side of the bar. Try this with a new chain, to make sure that the wear is in the bar groove and not the drive links.

View attachment 382114
The nose sprocket of a bar can also wear out long before this. If the side plates of the chain are riding on the guide rails, instead of on the bearings, the sprocket should be replaced.
View attachment 382115

In either case, you can continue to use the bar if the performance is acceptable to you, but they would both be considered 'worn' past the recommended service life.

Philbert

I tried this test with a new chain and the bar is at the end of its useful life. There is a small amount of daylight under the straightedge at the front of the cutter but none at the sharpening indicator at the back of the cutter.

Any suggestions for good aftermarket bars for a Stihl 028AV? Carlton? Forrester? Cheapest place to get them?

 

[Philbert]

Again, bottom line is how it cuts. A lot of guys save old bars and chains for dirty work, or as an emergency back up.

Cheapest is not always best. I would start with Bailey's and look for sales. Note that many brands have different quality levels at different price points. Better, longer wearing bars are . . .(well, you get it).

Philbert

 

[old-cat]

If you get a brand new STIHL 28" ES Light bar, your measurements will say it is wore out already.

 

[SawTroll]

Bar groove clearance varies widely between different bars. My 28" STIHL light bar seems worn out when it's brand new! I forgot what the numbers are.
The bar will wear far more on the rails than the groove. So you need to measure how much clearance the drivers have in the bottom of the groove. I wouldn't even bother with the width part.

That "wide part" in the upper groove "contributes" a lot to crooked cutting though - but there is of course no way to "measure" when that will happen - only using it will tell.
The same wide part will be a problem when using a larger gauge chain in the bar, after the bottom of the groove allows that.....

 

[SawTroll]

......

What is too worn for cutting through knots on an angle might work well enough just cutting at 90 degrees to the stem.

Horisontal vs. vertical cutting also matters, a bar may work for vertical cuts, but cut crooked in more or less horisontal ones.

 

[Matt81]

I have posted this e-book before but i will do so again for those interested. Sorry in advance but the pictures are not as nice as Philbert's ones from Oregon. Carlton's graphics budget was blown this particular year.

Carlton publication covering most things you need to know about chains, bars, sprockets and filing. Has a few pages in there about bar wear and crooked cutting from bar wear.

 

[old-cat]

That "wide part" in the upper groove "contributes" a lot to crooked cutting though - but there is of course no way to "measure" when that will happen - only using it will tell.
The same wide part will be a problem when using a larger gauge chain in the bar, after the bottom of the groove allows that.....

What you're talking about is totally different than what I am saying. I do agree, what you say is right BUT the clearance in the bar I referred to is much more than a lot of other bars and it works just fine!

 

[Philbert]

It the rails are just 'spread' out, sometimes they can be brought back together using a bar rail tool like this:

http://www.baileysonline.com/Chains...ols/WoodlandPRO-Chain-Saw-Bar-Rail-Closer.axd

This tool will not help if the insides of the groove are worn away, as shown in the Carlton book that Matt81 posted. It could help you get some more use out of a bar, but it is not a cure-all.

Philbert

 

[SawTroll]

It the rails are just 'spread' out, sometimes they can be brought back together using a bar rail tool like this:
.....
This tool will not help if the insides of the groove are worn away, as shown in the Carlton book that Matt81 posted. It could help you get some more use out of a bar, but it is not a cure-all.

Philbert

Yes, rail closers can be useful for "fixing" a wore out bar as a short-term "stop-gap", or for collectors items that see minimal use.

 

[Gypo Logger]

The BRC is a last resort if a larger gauge driver won't fit. The BRC pinches in the rails and not always evenly, so after using the BRC I use a stihl bar rail spreader.