Bar won’t cut straight on Stihl 660, is the bar toast?

My 32” bar won’t cut straight. I dressed the bar and filed the burs smooth, tried a couple different sharp chains and still cut crooked and would bind up in the cut. I switched about to a 30” bar and chain and problem solved. I would prefer to stay with the 32” bar because I have more chains to go with it.

how do I know if the bar is worn out, and what else can I do to try to fix it? Thanks

 

Sounds like your bar rails are still uneven. When you say you dressed it, how'd you do it? With a file by hand, table mounted belt sander or a bar dressing tool? I use a table mounted belt sander myself, and check the machine for square before proceeding. I also sand it, then flip the bar and sand it from the other direction just to be sure.

 

I just hand filed the nuts off. It makes sense that the rails are probably uneven. Is there a way to check and even out the rails?

 

Is the bar well used? Do you flip it to keep the wear even? What is you dressing method as Eric asked? Bench top disc sander the most reliable.

After I dress it (I use a Pferd bar dressing tool or a flat file if its minor) ill eyeball the groove looking up to the sky or bright light to see if its even then give it a try. My aging eyes don't see that well and if it still goes crooked or binds up I'll give it a second dressing.

Are you running the chain too loose? Its my understanding (someone please correct me if I'm wrong) doing that will wear the groove inside thus causing the same problem.

Worst case you can shorten the chains. I've had an OPE do this as well as Eric Wanderweg as he has a breaker tool and I bought several NOS 28 & 36" chains cheap. I don't often run longer bars.

 

A machinist square or this type of carpenter's square will work, if you've got a keen eye and/or a magnifying glass.

 

If the rails are true, the bar will stand up on edge on a flat level table. If the bar stands up, your chain sharpening vs raker height is uneven

 

Even a slight bend in the bar will cause this, too. Get a flat surface and check the bar to be sure it’s straight.

 

Make sure the bar hasn’t been dressed so much as to have the drive links touching the bottom of the bar groove. Really doubt this but it’s possible.

 

Running a narrower gauge of chain can cause this too. IE, running a .050 gauge chain in a .063 gauge bar.

 

That can happen if the groove in the bar has worn. You can close the groove by using a rail tightening tool. Sometimes you go up a size on the chain width, say from 050 to 063.
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I was gonna recco the 'wiggle test'. I tighten chain on questionable bar to my spec then go 6" up the bar and check how much lateral 'wiggle' I can make. If the tooth can make 20 degrees either direction then the drive links have likely wallered the bottom of the channel a bit. Aside from fill welding and regrooving unsure how to repair. I do own a bar dressing tool but not a closer.

 

Yep whenever this has happened to me it is uneven rails and occasionally a worn groove. I just set the bar on a smooth flat surface and see if it falls over. If it just leans a little it usually isn't enough to cause what you are describing.

 

I have experienced this with a saw that was not oiling sufficiently.

 

So I checked the bar to see if the rails are even, I stud it in a flat surface on the rails oand it was just fine, the rails are even. I then laid the bar flat and noticed there slight bow in the bar (bent bar). Any solutions to getting bow out of the bar? Obviously I could attempt to bend it back, but I’m worried I’d just bend it it the wrong spots and make it worse.

 

I have had bent bars that I’ve attempted to straighten with very limited success. You are not out anything to give it a try!

 

Like Ron said, it’s not worth much if it cuts crooked. Lay it across a couple 4 x 4‘s and stand on it. Might have to bounce or hit it with a sledgehammer.

 

I bent a 36" bar; took it to a machine shop, they straightened it like new with a 50 ton press. I told him to give it his best shot and not worry about ruining it because the bar was useless like it was anyway. I was impressed; I did not expect to ever use the bar again...

 

Wow that’s bent way worse than my 32”. I still can’t get it bent back after putting 2 2x4 underneath and jumping on it.

 

Do you have a jack? Put bar on 2x4 on each end , bottle jack in middle of bar. Use your truck weight, jack against truck, check the bar until straight