Bar issue?

[Treeaddict]

I put a grinder sharpened chain on a well used 20” bar. The saw cut straight and properly of the last 10” of bar was used. If the saw was dogged in, it would cut crooked IF I could get it to cut. It really didn’t want to do anything.

I’m assuming the bar needs dressing or replacing?

 

[lxskllr]

The rails might be getting sloppy. Check the gauge. Also make sure your chain is the right gauge if you pulled it out of a box used or something. Check the bar rail edges, See if there's mushrooming, and/or a heavy wirebead on the edge.

 

[CurSedVoyce]

Check your dogs as well. Loose dog could cause you some grief.

 

[Treeaddict]

All good except minor shrooming. Did find a very slight bow when placed on level surface. That could be the issue

 

[TINYHULK]

Can someone remind me what the tolerances are for bar groove? Other than our 251 everything is .050 gauge. How wide can the groove on the bar get until it’s “out of tolerance?”

 

[lxskllr]

Dunno what it is in absolute numbers, but if the cutter heels over when pushed, it's out of spec. The cutter should stand more or less vertical. I've read of people getting more out their bar by going up in gauge as the rails wear. Kind of ghetto for a professional outfit, but might be worth considering for a stumper bar.

 

[Treeaddict]

Bar closer. If the rails are out of spec with the sprocket or tail, I “close” them with this tool.

Who cares if it’s a shorter bar but I do like to get more mileage out of the larger ones.

Bars are now more expensive than ever though.

I don’t remember who makes this tool, unfortunately. The interweb can surely guide you if you wish.

 

[lxskllr]

Does that work pretty well for you? I've used a hammer with success, but that's been on the small cheap bars. I haven't had the need to close a pro bar yet.

 

[Treeaddict]

It definitely closes the rails. Proven by the micrometer

 

[SeanKroll]

Be sure not to over-close them.

 

[Treeaddict]

Be sure not to over-close them.

I set the closure depth at the sprocket where it is true to tolerances.

 

[Nutball]

Can someone remind me what the tolerances are for bar groove? Other than our 251 everything is .050 gauge. How wide can the groove on the bar get until it’s “out of tolerance?”

It gets too sloppy to use around .015" larger than nominal. That's my personal limit. .020 is way too much, I like it less than .007, but keeping it as tight as about .002 larger than the chain isn't easy since it wears wider quickly. The chain needs room for heat expansion, vibration, and sawdust between the links and rail sides.

 

[CurSedVoyce]

Figure 10/1000s is close to the a .063 gauge and past .058. Take your 050 chain and put it in an .058 bar. Or even an .063. I bet you get a nice sloppy cut.

 

[SeanKroll]

I am likely due to buy a closer. I've never closed any of my personal bars...all having any age to them are Stihl, run on canola oil.

 

[SeanKroll]

Guide Bar Maintenance | Madsen's Shop

www.madsens1.com

 

[Nutball]

I wish I had a rail squaring grinder. I've never gotten around to getting one.

 

[SeanKroll]

I don't think you really need one. For production bar maintenance, like a saw shop, sure, but for a tree service...

Pferd Universal Edge Sharpener Guide Bar Dresser

The Pferd universal edge sharpener was originally designed for truing up the steel edges of snowboards and skis. But for chainsaw operators, it serves a higher purpose - to help maintain your guide bar. It is ideal for removing the burrs that forms from standard chain wear. Simply remove the...

www.baileysonline.com

If you're feeling fancy. A regular file will do the trick, too, if you have a touch of finesse.

 

[Nutball]

The problem with the files is that the bar rails are often work hardened, and sometimes heat hardened. I should give it another try after gently removing the outer layer on a grinder to see if I can get through the hard stuff. My concern is either the file not working at all, or filing the softer parts lower than they need to be.

 

[Trains]

If the groove is closed back up, and the chain does not rock side to side when its in the bar rail groove, you can assume the bar is ok.
put a straight edge against the side of the bar, from lower rail to upper rail and over against the chain, does the chain get pushed away enough for the straight edge to lay flat against the side of the bar ?, check both sides, if so, its got uneven wear along the bar rail, the top may be closed, but below that its belled out and allows the chain to rock.

but it does sound like the chain is rocking side to side a bit, that stops it self feeding, and can cause a cut that is not straight.
It also can be the chain too.

When you sharpened the chain, did you also file the rakers as well.

A progressive raker guide is best for getting the most out of the chain, especially after the tooth is brought back to half its original size.

Your picture shows a bit of wear, I would assume its just forward of the dogs, and when you dog in, and put load on the bar, with the chain not sharp, causes that type of wear.
flatten it so the rails are smooth and even, take off the lip, and bevel the sides so it wont catch your nail/ finger skin.

Need pics of the chain in it with straight edge pushing the chain to the side to see how much it can move in the bar groove.

 

[Treeaddict]

Trains, the cause was the bowed bar. Chain is good. Bar has been thoroughly dressed. The bow was causing it to bind in the cut. That’s why the last 8” cut so well but when I sunk my dogs in it wouldn’t cut. The question is, how the heck did that happen. I don’t remember any sort of incident that could have put pressure on the bar in that way. 🤷‍♂️.

Traded it out for the spare. Maybe I can get the bow out of it.

Ah well, better the 20” than the 54” I suppose.

 

[Trains]

I missed the bit where it had a bow, had sick kids and a sleepless weekend, so blaming that .

Glad you got it sorted.

 

[davidwyby]

I got a bar rail closer against the advice of a more seasoned guy and have not had good luck with it, to my embarrassment. I ended up taking his advice and putting a shim between the rails and tap tap tapping the rails down. *tap at about 45° into the corner, not straight down.

 

[Nutball]

I've only used a closer on laminated bars, and it works well. The main issue I see with closing rails on any bar is if their thickness is uneven such that one rail bends in easier than the other making it crooked. I mainly use it on new bars to make them tighter from the start since Oregon laminated bars are wide from the start with pain between the rails that quickly wears off effectively increasing the gauge in a couple hours use.

 

[huskihl]

Belt sander works pretty quick for squaring up bar rails. See if your bar will stand on edge on top of a flat table. If it won’t stand up on its own the rails need dressed. I lock the bar in my bench vise and hold the belt sander sideways eyed up as flat as you can and run up and down the bar a couple times. And then run on a 45 to knock the burrs off the side. The belt sander isn’t perfect but I’ve always been able to make the bar stand up on its own.

 

[Treeaddict]

Belt sander works pretty quick for squaring up bar rails. See if your bar will stand on edge on top of a flat table. If it won’t stand up on its own the rails need dressed. I lock the bar in my bench vise and hold the belt sander sideways eyed up as flat as you can and run up and down the bar a couple times. And then run on a 45 to knock the burrs off the side. The belt sander isn’t perfect but I’ve always been able to make the bar stand up on its own.

@huskihl I’m sure the belt sander makes quick work of it Good ideas. Use 60-80 grit?