Chain tension tight then loose at another spot

[Timjus]

all my .325 1.3mm chains have big loose spots when new.

 

[Ford3000]

all my .325 1.3mm chains have big loose spots when new.

I had no idea such could be, with the speed involved I would have thought
chains were pretty spot on with all links equal in length.
Either way, I will give it a spin in some wood and see how it goes.

The chains I currently use and make mention of are .058 / 1.5 mm.

I have for now given up on finding a NK bar for this saw, I tried a few
Husqvarna and Oregon and none had the oil hole high enough up the bar to
allow for proper oiling, the closest was the Oregon Speed Cut, but it was half
a hole out, and the hole was very small, much smaller than the hole on the bar
that came with the saw, which states Efco and has an Oregon crest on it too.

The bar that does fit is a Carlton 01W, but it does not take NK chain, so no good.

 

[big_eddy]

1) the crankshaft does not rotate when you pull the chain by hand, so not the crank or bearings. (assuming engine off!!)
2) if the rim sprocket, then the tightness / looseness will occur every 7-8 drive links i.e. 3-4 teeth.
3) If the sprocket nose - then the tightness / looseness will occur 3-5 times per rotation of the chain - depending on bar length.
4) If the tightness occurs once or twice per chain revolution - then most likely you have a tight spot in the chain that does not like to make the curve for the nose or rim sprocket, or a stretched spot in the chain that "tightens up" when the drive tangs are forced to conform to the rim sprocket spacing.

 

[Ford3000]

1) the crankshaft does not rotate when you pull the chain by hand, so not the crank or bearings. (assuming engine off!!)
2) if the rim sprocket, then the tightness / looseness will occur every 7-8 drive links i.e. 3-4 teeth.
3) If the sprocket nose - then the tightness / looseness will occur 3-5 times per rotation of the chain - depending on bar length.
4) If the tightness occurs once or twice per chain revolution - then most likely you have a tight spot in the chain that does not like to make the curve for the nose or rim sprocket, or a stretched spot in the chain that "tightens up" when the drive tangs are forced to conform to the rim sprocket spacing.

Makes perfect sense @big_eddy , the crank not rotating came to me like a nightmare after posting here last night, this lead me to investigate further today.
I firstly examined the chains, and found a tightness, then I found a damaged
teeth, it took a good whack, so my nicely put away bar and two chains were taken out by someone and used to cut wood with nails or whatever in them, I had no idea inlaws could be so sneaky, I will play them at their own game and set the chains back with sharpened tags, after filing them blunt, and watch for the fun.

I bought a new Stihl chain and put it on the original bar, it seems almost perfect as I rotate it by hand, so will know better when I get to cutting.

I tired a few bars today and could not find one that has an oil hole that
lines up with the Efco, they were all a few mm short of where the hole height needs to be, and the holes were also a good bit smaller than the ones on the Efco bar, I gave up, and will revisit finding a NK bar for this saw at another time.

 

[Nutball]

You could drill a new oil hole. That's what I do when putting Stihl bars on a 2511t, and for the Oregon bars that were supposed to fit my 9010.

 

[Ford3000]

You could drill a new oil hole. That's what I do when putting Stihl bars on a 2511t, and for the Oregon bars that were supposed to fit my 9010.

Thanks @Nutball , but I have no means of drilling a hole that would
overlap the hole already there, I lost the building I used to work in and
have sold off most of my tools, no where to store them, I only need a saw
for keeping the trees around the house trimmed, some firewood and I help
out a woman with a bad leg.
To get someone to mill a hole in a bar here would take some time, those that
are any good are too busy for small jobs. The tails on the bars I tried today
were also off, they were more tapered down than the original, not so sure how that would effect the chain running into the rails, could be too slack on the top and drop too much then get slammed up onto the rails, so just left it until I have time to find out more.

 

[popopboat]

Had the same "issue", sprocket hole was offset by few thousands.

 

[Ford3000]

Had the same "issue", sprocket hole was offset by few thousands.

The sprocket on the end of the bar or the one on the drive shaft.
Was it on the same model of saw.

 

[dahmer]

The sprocket on the end of the bar or the one on the drive shaft.
Was it on the same model of saw.

We just had some rim drive sprockets that were off. Since many saws run the same rim the problem could show up on different saws. The rims were a Chinese off brand.

 

[kneedeepinsaws]

We just had some rim drive sprockets that were off. Since many saws run the same rim the problem could show up on different saws. The rims were a Chinese off brand.

Dang good to know!!!!! I always would have thought rims were perfect lol never would have suspected that!!!! Don’t know why now that I think about it !

 

[Ford3000]

Dang good to know!!!!! I always would have thought rims were perfect lol never would have suspected that!!!! Don’t know why now that I think about it !

Given the speed they rotate at I was under the impression they would all have to be well balanced.