why won't my 880 cut straight?

[shillo]

Driving me bonkers.

 

Bar seams straight

Rails are even and at right angle, checked with square

Chain is sharp, cutters same length, checked with calipers

Depth gauges right

Bar not done much work.

 

As soon as the bar get to bar length stuff it turns sharp and won't cut any more.

 

As you can see from the pics, hopefully, i filed the rails flat and dressed, not that they noticeably bad to start with. tried the saw again. still no good, took bar and chain off again and one side of the rail seams like its been battered (first pic) and its formed bit of a burr already after 20seconds cutting.

It also seams to be wearing the bottom of the chain abnormally.

This chain was new but I've tried re sharpening it so many times now thinking that it must be the chain that it now 1/4 worn.

Same is happening with a new chain, so it must be the bar, Right?? but i can't see anything wrong with it.

I don't think the rails are splayed, would that cause the problems I'm having?

 

my 42'' bar and chain works fine

 

Any help appreciated

[spudulike]

It is possible that the rails are splayed and the chain is kicking over a little allowing only the cuters on one side to cut.

 

Try moving the chain from side to side in the bar and see how much it wobbles from side to side.

 

Other usual suspects are the rails uneven - best put the bar in a bench vice and lay a straight edge across it at different positions and check it is at right angles to the bar.

[billpierce]

i have had this exact same problem and are yet to solve it. it has on an elderly husky bar and what spud says about splayed rails was my conclusion as i like you it was happening on a new chain.

 

my bar looks good with a steel ruler against it and right angle on the rails but when buried in a cut catches and feels like its really badly burred.

 

do you reckon the bar has been around for a good bit?

[shillo]

Flippin heck, that was quick!

 

I did try to see how much wobble there is and there was a bit more wobble in the middle of the bar.

If you hold a straight edge up the side of the bar as per oregon bar maintenance instruction, and check for chain deviation (wobble) the chain wobbles way too much along the whole length of the bar

 

is it possible to un splay rails?

 

What causes splaying?

 

I've never had it happen to me before on any other bar?

[AHPP]

Rails too low so bottom of drive link is bottoming out on bottom of groove. Put some metal back on the rails.

[spudulike]

Flippin heck, that was quick!

 

I did try to see how much wobble there is and there was a bit more wobble in the middle of the bar.

If you hold a straight edge up the side of the bar as per oregon bar maintenance instruction, and check for chain deviation (wobble) the chain wobbles way too much along the whole length of the bar

 

is it possible to un splay rails?

 

What causes splaying?

 

I've never had it happen to me before on any other bar?

 

 

You can hammer the rails back in to shape - you need a solid bench vice and a mid size hammer and give the hammer a decent wallop and let it bounce on the bar after the hit, do this at close intervals along both sides of the bar on the rails and keep checking with the chain and avoid over closing the rail as it will pinch. If it does this, seperate the rails with a large screwdriver - a little harsh but it will work if you are carefull and patient.

 

The splay is just bending, overheating or wear!

 

The above may not last a long time but may be worth a punt.

 

Good point on the depth of the rails - generally must be 5mm + or the standard depth of the drive link plus a clearance!

[billpierce]

i'll give it a go! oh and the rails have enough depth thanks

[AHPP]

Interesting. What are the bottom of the drive links fouling? Is there maybe one low point or something stuck in the groove?

[agg221]

I have had this problem, and fixed it by judicious use of a hammer and screwdriver as described by Spud. I now have a fancy gizmo for truing up the rails when they splay, which is very handy as I tend to run long, old bars right down to the limits.

 

Alec

[arboriculturist]

Have you compared this bar with your 42" bar?

 

Especially the splaying aspect - measure width on both bars at top of groove with micrometer over the full length every 100mm - mark with tape measure and chalk.

 

Double check groove depth in relation to chain being used. Again compare bars.

 

Are your depth guages all the same height and if so are they filed to the correct height in relation to the cutters?

 

Are the right and left hand cutters 80% perfect i.e. outside cutting corners undamaged i.e. no rounding off you have not noticed?

Even subtle damage to left or right cutters can cause chain to cut in a curve

 

Does it have same symptoms with new chain? - if so we can all deduce its a bar defect.