Trying to fix curved cuts w/o new bar or chain

[pondnstream]

Hi ,

Saw husky 3120
Bar 3/8. 0.058 84DL

Recently I’ve been challenged to correct a bar and chain that wouldn’t cut straight but without buying new chain or bar which would be the easiest and probably the best solution but I wanted to see if I could DIY cure the problem of very bad curved cutting.

I did all the following and it cut much straighter but still wasn’t perfect and still wanted to cut a bit to one side:

1. Filed All cutters same length

2. Filed all rakers same height

3. Filed Bar rails same height and square to side of bar

4. Squeezed and hammered the Bar rails snug against chain so that chain doesn’t move from side to side but still slides in bar.

A friend and I spent several hours trying to get the rails closed to the point of being snug against the chain but not too tight. We tried a roller , then hammering , then a large vise. None of these were the perfect solution to move the side rails in the thousandths of inch to the exact spot. In the end we got close but had some hot spots where it was too tight against the chain.

Couple of questions :

a) Does a straight and flat a bar sometimes become uneven and beyond correction ?

b) Does a chain that’s been run in a bar with uneven rails get worn to the point where it won’t cut straight even on a good bar ?

c) was I mistaken by thinking the curve cutting was caused by bar rails gauge that was too wide and my real problem was the chain’s drive links were worn and causing the chain to lean and not stand up straight on the bar ?

d) What’s the best easiest to use tool for closing the rails ?

Thanks

 

[singinwoodwackr]

Yes, yes, don’t know as I’d need more info
What did you use to true the bar rails with?

 

[pondnstream]

To cl

Yes, yes, don’t know as I’d need more info
What did you use to true the bar rails with

To close the rails , we tried several things:

1st , a jeweler’s roller used to squeeze flat stock and make it thinner , we had to add a thin piece of steel over the rail so it would just squeeze at that point .

2nd, carefully hammering

3rd, large vise wit bar 1/4” between jaws and rotating handle to same point and working across the width of the bar.

 

[singinwoodwackr]

Yes, yes, don’t know as I’d need more info
What did you use to true the bar rails

To cl


To close the rails , we tried several things:

1st , a jeweler’s roller used to squeeze flat stock and make it thinner , we had to add a thin piece of steel over the rail so it would just squeeze at that point .

2nd, carefully hammering

3rd, large vise wit bar 1/4” between jaws and rotating handle to same point and working across the width of the bar.

no, what did you make the rails 90* with?

 

[singinwoodwackr]

The single most common cause of curved cuts is the rails out of true. 1/2 a degree off will do it.

And, did you true the rails before or after pinching? Must do it after.

 

[Marley5]

I've had this happen once in 50 years.
Was using a sharpening jig and sharpened the same side of chain twice and unintentionally avoided opposite side...... not good
Chain tension
Worn bar
Did the dummy thing like I did

 

[singinwoodwackr]

I've had this happen once in 50 years.
Was using a sharpening jig and sharpened the same side of chain twice and unintentionally avoided opposite side...... not good
Chain tension
Worn bar
Did the dummy thing like I did

Yea, that would do it

 

[pondnstream]

To dress the rails and make them equal height and square to the side of bar tried the file technique then a disc sander .

Did not go back and re true the rail heights after the pinching and setting the gauge . Will now do that on the disc sander with 90 degree table .

Tried using a file and machinist’s square but have to keep checking, disc sander with right angle table seems better.

 

[Mad Professor]

To dress the rails and make them equal height and square to the side of bar tried the file technique then a disc sander .

Did not go back and re true the rail heights after the pinching and setting the gauge . Will now do that on the disc sander with 90 degree table .

Tried using a file and machinist’s square but have to keep checking, disc sander with right angle table seems better.

Better than a disc sander is a vertical belt sander set at 90 degrees. I've recovered a few bars people were going to toss as scrap.

 

[singinwoodwackr]

To dress the rails and make them equal height and square to the side of bar tried the file technique then a disc sander .

Did not go back and re true the rail heights after the pinching and setting the gauge . Will now do that on the disc sander with 90 degree table .

Tried using a file and machinist’s square but have to keep checking, disc sander with right angle table seems better.

Make sure the sander table is dead on 90*. I use a quality machinist sq and re-check it often.
I’ve used a delta 1x30” belt sander for decades…60g Zircon belts.
I’ve redone dozens of bars the owners thought they’d squared up.

The problem with using a disc sander for bars is it will want to pull/push…up cut and down cut at the same time. A vertical belt sander is a lot better.

 

[J D]

Firstly, are you sure both bar & chain are 0.058"? Still chain is only commonly available in 050 or 063 in many places... & you'll never close up a bar rail well enough to run an undersize chain without issues.
You can see the blue spots on the bar where the rails are too tight, pry them open a touch with an appropriate size screw driver so a drive link slides through freely.
That chain doesn't look to be as well sharpened as it could be... needs more hook, a sharper working corner, & on a 3120 probably a fair bit more off the rakers. The right side looks to be better than the left from what I can see.
To answer your questions:
a) yes, when the rails have been filed/ worn to the point the drive links bottom out in the groove.
b) can do, if the drive links are worn to a V or tie strap bottoms are worn excessively on one side. The tie straps look to be quite worn around the heel of the cutters on that chain.
c) probably a combination of both but more likely that the bar rails are the significant contributor to the issue. A mismatched bar & chain guage will cause this.
d) a bar rail closer

 

[Tnjind]

Did you try flipping the bar, do an up cut to see if it follows?

 

[pondnstream]

Did you try flipping the bar, do an up cut to see if it follows?

Not yet but I will .

Is the idea of an upcut , to check the top side of the bar without having to remove and flip the bar ?.

 

[Mad Professor]

Not yet but I will .

Is the idea of an upcut , to check the top side of the bar without having to remove and flip the bar ?.

You should flip the bar every few chain sharpenings, clean the groove and around the clutch at the same time.

 

[Okie]

The picture you posted shows a worn out chain and bar. Very doubtful you will ever get a perfect straight cut with that combo. As you say, CHALLENGED TO GET A good cut.
Appears to me it's time to get a bar, chain and probably replace the sprocket.

Only other option is to replace the chain and sprocket and if you cannot live with the cut then replace the bar.

 

[blades]

With all of the above the other little tid bit is operator. The weight of the saw itself hanging out on one side is a contributor if not paying very close attention. Once you get into 60cc and above that is a significant chunk hanging there.

 

[dave ensign]

IF you have uneven ware on the bottom side of the chain you won't ever get that chain to cut very straight.

 

[thenne1713]

Hi ,

Saw husky 3120
Bar 3/8. 0.058 84DL

Recently I’ve been challenged to correct a bar and chain that wouldn’t cut straight but without buying new chain or bar which would be the easiest and probably the best solution but I wanted to see if I could DIY cure the problem of very bad curved cutting.

I did all the following and it cut much straighter but still wasn’t perfect and still wanted to cut a bit to one side:

1. Filed All cutters same length

2. Filed all rakers same height

3. Filed Bar rails same height and square to side of bar

4. Squeezed and hammered the Bar rails snug against chain so that chain doesn’t move from side to side but still slides in bar.

A friend and I spent several hours trying to get the rails closed to the point of being snug against the chain but not too tight. We tried a roller , then hammering , then a large vise. None of these were the perfect solution to move the side rails in the thousandths of inch to the exact spot. In the end we got close but had some hot spots where it was too tight against the chain.

Couple of questions :

a) Does a straight and flat a bar sometimes become uneven and beyond correction ?

b) Does a chain that’s been run in a bar with uneven rails get worn to the point where it won’t cut straight even on a good bar ?

c) was I mistaken by thinking the curve cutting was caused by bar rails gauge that was too wide and my real problem was the chain’s drive links were worn and causing the chain to lean and not stand up straight on the bar ?

d) What’s the best easiest to use tool for closing the rails ?

Thanks
View attachment 1245037View attachment 1245038

To cl


To close the rails , we tried several things:

1st , a jeweler’s roller used to squeeze flat stock and make it thinner , we had to add a thin piece of steel over the rail so it would just squeeze at that point .

2nd, carefully hammering

3rd, large vise wit bar 1/4” between jaws and rotating handle to same point and working across the width of t he bar.

I have encountered the issue only twice, once while bucking after filing, once while milling, after sharpening. Easiest way to troubleshoot is always carry 3-4 chains, and switch to another chain. I will now field file only x2-x3, then switch chains and bench grind all every night. I now use the 2N1 file jig. If fresh chain still does it, issue is bar, but bar issues usually very evident. I also carry both 20 and 24".

To cl


To close the rails , we tried several things:

1st , a jeweler’s roller used to squeeze flat stock and make it thinner , we had to add a thin piece of steel over the rail so it would just squeeze at that point .

2nd, carefully hammering

3rd, large vise wit bar 1/4” between jaws and rotating handle to same point and working across the width of the bar.

I have encountered the issue only twice, once while bucking after filing, once while milling, after sharpening. Easiest way to troubleshoot is always carry 3-4 chains, and switch to another chain. I will now field file only x2-x3, then switch chains and bench grind all every night. I now use the 2N1 file jig. If fresh chain still does it, issue is bar, but bar issues usually very evident. I also carry both 20 and 24".