Chains won't cut anymore

[BrewBoy]

I have several loops of 3/8 .063 chisel chain that I've been rotating over the years on a MS46o Stihl. Lately I sharpen the chain at 30 degrees and it doesn't cut well. I've lowered the guides almost to the stamped mark and they still don't cut well. I would say that at least half of the cutter length(s) are still present.

Should I change the angle or ??? I'm afraid to take the guides down any further. I don't do this for a living, so I apologize in advance if I don't use the correct terminology. Thanks.

 

[BlueRidgeMark]

Hi! Welcome to AS!



Have you lowered the rakers? A.K.A. depth gauges? Or is that what you're calling the "guides"?


Madsen's has a great bunch of info on chains and sharpening. It's worth spending a few moments with it.

http://www.madsens1.com/MNUbarchain.htm

For now, you can probably ignore the info about "square chisel" chain. Pros use it, but we weekend warriors usually stick with round chisel.


As for sharpening, what are you using?

 

[BrewBoy]

Yes, I've lowered the rakers ( guides as I called them). I've been using a HF style (mine is not their brand, but the one I think they copied) of grinder for many years and have never had this problem. In between grinds I'll hit it with a file.

I have checked the rakers with a .030 gauge and they seem to actually be a little lower than that, but still I'm working myself to death to get it to cut.

I will check out that link you recommended and thanks for the welcome.

 

[redoakneck]

If you have 1/2 the cutter left you should be able to still sharpen them back to new.
Check your raker height compared to your cutter height, the raker should be 0.025" below the cutter.

Check out the pics on the chainsaw sharpening thread. Also if you could post pics here we may better be able to help.

Another option and worth the time and money is to have a dealer sharpen them. Take your bar also, very cheap to "tuned up". If your chain is way off this may be your best bet.

 

[gemniii]

Before when you sharpened the chains did you get nice chips?
Here's a pic mdavelee posted of some nice chips:

There are several angles important, as explained at madsen's site. Although I don't know how BlueRidgemark could have suggested "a few moments". I think it's a good portion of an hour at least. The little corner at the leading edge of the cutter is probably the most important.

If your grinding wheel isn't working properly have you tried hand filing?

The rakers might actually be a little too low.

Buy a new chain and compare it to your present chains.

Note that the HF grinder has often been found as less than desirable in threads here. I've only used my $90 NT grinder.

 

[trimmmed]

The angle should be fine.

First check that you are in fact making a point.

 

[BrewBoy]

I'll try and get some pictures of one of the suspect blades. Thanks again for the replies.


gemniii I was getting very small chips that was closer to course dust. I was really pushing hard on the saw as well. My sore back confirms that.

 

[gemniii]

gemniii I was getting very small chips that was closer to course dust. I was really pushing hard on the saw as well. My sore back confirms that.

I suspected that was the case. I haven't done a lot of felling, or crosscutting. Most of my limited work has been done milling.

For example:

I'll start on an 8' long log, have nice chips at the start and fair chips at the end of one slice. By the end of the second cut it's often getting like dust.

Be careful when you start having to push hard, that's when you should lay back with a non-alcoholic beverage, and a file, and quickly touch up the chain. Often four good strokes on each cutter will save you timeover the entire job.

Despite others suggestions "taking to a dealer" can be a gamble. There are a lot of horror stories of bad chain sharpening by dealerships.

I'm waiting for some entrepreneurial AS teenager to start a netflix style chain service with good quality control.

 

[Philbert]

I sharpen the chain at 30 degrees and it doesn't cut well. I've lowered the guides almost to the stamped mark and they still don't cut well.

Welcome to A.S.!

I would not lower your depth gauges any more, just yet; you can always do that later if needed, but you can't put any more back on.

I don't know if you do any woodworking, but it is helpful to think of each cutter as a chisel or plane. Except that each cutter has 2 cutting edges; one on the top plate, and one on the side plate, as the illustrations from Oregon and STIHL (below) show.

Like a chisel, the profile angle (file guide angle in the top illustration) is an important part of the cutter's shape and performance, but you can have a 30 degree cutter profile and still have a dull edge. Both the top plate cutting edge and the side plate cutting edge need to be sharp, again like chisels.

The top plate edge separates the wood fibers when cross cutting and the side plate edge severs the fibers. If only one edge is sharp, you will experience poor cutting performance. Like on a woodworking plane, the depth gauges control how deep the cutter digs with each pass: too shallow and you don't take much wood; too deep and the teeth grab rather than cut.

Check to see if both edges are uniformly sharp on each cutter. If they are not, look at the way that the grinding wheel touches each edge. If you are not using the right size (thickness) wheel for your chain, if the profile/edge of the wheel is not dressed (half-round radius), if the head tilt on your grinder is not correct (typically 60 degrees) or if it is not grinding right up to the edge, you will not get sharp cutting edges on both the top and side plates.

Also visit the STIHL website and watch the video 'Chapter 3: Sharpening your Saw Chain'. This is for hand filing, but it may help you understand what you are doing with your grinder. http://stihldealer.net/videolibrary/


Philbert

 

[betterbuilt]

Yes, I've lowered the rakers ( guides as I called them). I've been using a HF style (mine is not their brand, but the one I think they copied) of grinder for many years and have never had this problem. In between grinds I'll hit it with a file.

I have checked the rakers with a .030 gauge and they seem to actually be a little lower than that, but still I'm working myself to death to get it to cut.

I will check out that link you recommended and thanks for the welcome.

Can you post a picture of your chain. It would be a lot easier if we can see what your talking about.

I have a few chains that I use only for fire wood and the rakers are Ground just about off and they cut just fine. The only problem I do have is if I push the saw it can't keep up.

 

[BrewBoy]

After reading the links/suggestions here and looking at my chains, I'm starting to think my problem is that I'm grinding it too deep in an effort to remove the gullet at the same time. Here are some pictures:

The first three are before I resharpened it at a shallower depth. Even though the saw had only been used a little after this sharpening, I can see that the point was never sharp or dulled quickly.

The last three are after I sharpened it.

Let me know what you think and thanks again for all of the help.

 

[showrguy]

i've seen worse..
it's hard to tell in the pictures, but, have you checked the bar for flair ??
check with fingernail, go from flat edge of bar toward chain, your fingernail should not stop till you touch the chain........file that flair off...
it's most likely worse closest to the powerhead..
my .02 cents

 

[BrewBoy]

Actually, I do have that. It like a sharp lip on either side of the bar under the chain. I can remove it, but how could that cause it not to cut, unless it prevents the bar from entering the saw kerf.

 

[betterbuilt]

Like showrguy said. I've seen worse.


That flair or knife edge can catch in the cut and not allow the chain to feed. Another problem I've had is the chain can wear enough that the chain actually becomes loose from side to side in the bar. I thought it was the bar but it was actually the chain was wore out. It was a pretty new looking chain.

Hows is the rim or sprocket? Not that it is the problem, but the chain hammer looks like it might be time to check the rim.

 

[gemniii]

The before pictures seemed to show more hook and and a sharper angle.

 

[showrguy]

Actually, I do have that. It like a sharp lip on either side of the bar under the chain. I can remove it, but how could that cause it not to cut, unless it prevents the bar from entering the saw kerf.

the flair will catch on whatever your cutting, you'll push harder, it'll get worse..
remove that flare, git a good sharpening on your chain, you'll think you have a new saw..
good luck

 

[BrewBoy]

I haven't changed the angle. They were both ground at 30 degrees. However, the Madsen site mentioned in the first reply, says to use 15 or 20 degrees. That's quite a bit different than I'm doing.

 

[gemniii]

How do you determine the angle they were ground at?

The angle you have there is more like ripping chain, instead of 30 degrees.

/edit I flipped your pic so it was oriented more closely to the printed example.

Also, do you run your chains backwards sometimes? My chains never look so rounded in the back.

 

[BrewBoy]

I promise you it's not like it looks in that photo you altered. That looks like 0 degrees. I have an adjustable protractor and I checked it today, If anything it's greater than 30 degrees. I use a small table top grinder, It's called Nick the grinder, Looks similar to the HF ones, but I think they copied this one.

Also, I don't run the chains backwards. At least not on purpose. :hmm3grin2orange:

 

[Whiteman]

Also, do you run your chains backwards sometimes? My chains never look so rounded in the back.[/QUOTE]

I was thinking the same thing.