Why does saw cut better on a curve?

[terrifictimbersllc]

I've noticed, I think when chains are getting worn, that a sharp chain will still cut very easily but only if I let the cut curve around to the left as I go through the log. When this is happening, if I restrain the saw trying to make a straight cut,  it just won't saw.  Anyone know what causes this? Bar top not square? One side teeth shorter than the other?   

[Kevin]

The rakers or depth gauges could be longer on one side and not cutting as much wood on that side of the chain.

[John Mc]

Bar rails work unevenly?

[Sprucegum]

My saw cut like that when I was first learning how to sharpen the chain. Being right-handed, one side was getting sharpened better than the other. Once I learned to treat both sides evenly the cut straightened out.

[JohnG28]

I think Sprucegum could be right.  If you favor one side of the chain when sharpening you will have this effect.  Is it possible to have the chain sharpened at a shop where they can put it on a grinder and even them out? 

[terrifictimbersllc]

When it stops raining I'll have a close look at one saw which is doing it now.  Grind periodically on the grinder to get teeth the same length.  Pretty sure I'm treating both sides evenly on hand filing but who knows. 

[Tom]

It doesn't necessarily have to be something you are doing.   If you hit some dirt, a rock or a little nail, one side of the chain cutters might have been damaged more than the other side, so, one side will cut faster than the other.

When a saw begins to get a little dull, we are tempted to press harder and even use the bucking teeth more aggressively.  If you are right handed, you might be using your left hand to push down and where your hand is situated on the fore handle will determine which side of the chain gets the most pressure.  Hold the saw securely, but without pressing down, and see if it cuts straight.

[JohnG28]

Thats a good point, it doesnt necessarily have to be an error in filing, but does point twards one side wearing more than the other.  Tried a new chain to see if that cuts different or better?

[Ianab]

Bar rails work unevenly?

Thats what I would check if there is no obvious problem with the chain.

You should be able to take the bar off and stand it upright on edge, so it sitting on the rails. If they are worn unevenly the bar will keep falling over. If thats the case, flip the bar over and use the other side. If thats also worn, you need to get the bar dressed (ground down even). After it's been dressed a few times the groove will start to get too shallow for the chain drive spurs to run in. Then it's time for a new bar.

Ian

[quietrangr]

Put the chain in a new bar. If you get straighter cutting the problem is more likely that the chain drivers are worn, and the chain is simply laying over, or sort of flopping over to one side. This will happen sooner if the bar is also worn. I generally run a chain through at least two bars, a worn one when the chain is new, a less worn bar when the chain is midway, and a new bar when the chain is getting toward the end of its useful life.

[Meadows Miller]

My saw cut like that when I was first learning how to sharpen the chain. Being right-handed, one side was getting sharpened better than the other. Once I learned to treat both sides evenly the cut straightened out.

The rakers or depth gauges could be longer on one side and not cutting as much wood on that side of the chain.

Gday and firstly welcome to the Forum if i havent already said Gday Mate 

Itll most likely be either one of them  but its a tricky thing to rectify in a short post and its 12.30am here im knackerd and  headn to bed  if someone can please bump this back up tomorrow ill go into afew diferent ways you can fix it easy mate   

Regards Chris

[timber tramp]

    >>if someone can please bump this back up tomorrow ill go into afew diferent ways you can fix it easy mate     

Regards Chris
 

        Bump, there you go Chris.            TT

[thecfarm]

I hand sharpen and take more off on one side than the other. I just take one less stroke when the motor is on the right side when I sharpen the chain.Been doing this for more than 20 years,works for me. I can bring a chain back from hitting a rock or when I cut a stump down with 3-8 trees growing out of it.

[John Mc]

I'd still take a good look at the bar rails. I had those exact symptoms. The first time I really noticed the saw wanting to wander off to one side, I thought I was doing it by how I held the saw. I could force it to go straight but after a while the curving tendency got worse... enough so that the saw bogged down as it got deep enough for the back side of the bar to enter the cut.

Squaring up the bar rails with this Pferd Universal Edge Sharpener (in stock at forum sponsor, Baileys) took care of the problem. I bought it right after my local saw shop diagnosed the problem and trued up the bar on their belt sander (which had a little table to hold the bar square to the belt).

If you think about the geometry of this, it makes sense. If one of the bar rails is worn more than the other, the chains will be slightly tilted out of the plane of the bar. It will cut towards the tilt. It doesn't take much to cause this... it's often something you can just eyeball while it's on the saw. In fact, the chain may sit square, resting on one bar rail until it hits the log. Then it settles on to both of the rails.

I'm not trying to claim uneven bar wear is the only cause of this problem. It may well be how the saw is sharpened. In fact, if you have a chain that is sharpened in such a way that the saw wants to cut on a curve, that can cause uneven bar wear. As you try to adjust your pressure to keep the saw cutting straight, you'll accelerate wear on one of the bar rails. This can give you a "double-whammy" - both the chain and the bar are trying to push your cut into a curve. Putting on a new chain may improve things slightly, but the uneven bar will still make the saw cut on a curve.

[01crewcab]

I would just about bet your right vs left hand cutters are filed to a different length. Most right handed people will will always tend to file the right hand cutters down farther than the left hand ones.

[HolmenTree]

I've noticed, I think when chains are getting worn, that a sharp chain will still cut very easily but only if I let the cut curve around to the left as I go through the log. When this is happening, if I restrain the saw trying to make a straight cut,  it just won't saw.  Anyone know what causes this? Bar top not square? One side teeth shorter than the other?  

Your chain is cutting to the left as your crosscutting down through the log, which only means your right hand cutters are much duller then the left hand cutters.
You probably hit some dirt or some abrasion while falling a tree dulling those right hand cutters, or hitting some metal etc while bucking a log.
I have had bars with uneven rails, sloppy spread as all heck, left hand cutters bigger then the right hand cutters ........ but as long as all cutters are sharp the chain will cut straight in a downwards cut. A felling cut with the b/c on its side is a different story.

If I rock out my chains on one side only, I don't try to sharpen all the cutters to the same smaller size . A little difference in left and right cutter size is no big deal as long as your not always cutting big logs taking up the total length of the bar.
Keep all those cutters  sharp and the bar rail kerf tight.

Willard.

[Brucer]

I cut curves a lot when I'm bucking Douglas-Fir in the log yard.

D-Fir has thick, fissured bark that hold (and hides) dirt real easy. Whenever the saw starts to curve I resharpen the chain and the problem goes away. Obvious conclusion -- cutters on one side dulled more than on the other.

I have had problems with the cutters on one side filed shorter than on the other, but only when the rails were spread open. I've also had problems with the depth gauges filed differently on one side versus the other. Again, this only showed up with the rails spread.

So, sharpen first, then look for other issues.

[arojay]

Yep, sharpening issues are cheapest and easiest place to start.  Pick up a filing guide of some kind.  Carlton file-o-plates are great IMHO, but there are several kinds.  If you are assured that your chain is filed correctly then move on to bar issues.  Spread or uneven bar rails are best repaired with some special tools that may not be worth the money if you don't cut a lot so a good dealer or repair shop might be the way to go.   

[SawTroll]

My saw cut like that when I was first learning how to sharpen the chain. Being right-handed, one side was getting sharpened better than the other. Once I learned to treat both sides evenly the cut straightened out.

Yes, that is most likely the cause!   

[ladylake]

I bought a saw off Ebay once that had the links where they hit the bar on the chain wore off more on one side, that one took a while to figure out, chain went in the garbage.    Steve

[LorenB]

I replaced a perfectly good bar with a new one when I had the same problem.  It wasn't until AFTER I threw the first bar away that I realized the problem was with the chain. 

I'll bet it's either you're favoring one side when sharpening or the rakers are different on each side. 

Good luck.

-- Loren

[SawTroll]

I bought a saw off Ebay once that had the links where they hit the bar on the chain wore off more on one side, that one took a while to figure out, chain went in the garbage.    Steve

Some times it just isn't worth the trouble to save a chain that others have messed up, or one that you seriously rocked out!