Thread: Chainsaw sharpening, file or grinder?

Originally Posted by Old Hilly

Just a simple question, which is the better way to sharpen your chainsaw, with a round file or with a grinding wheel? I realise we need to be gentle with the wheel so as not to overheat the tooth material but is there a difference in the shape of the cutting edge and what effect does it have on performance? My query applies to cross-cutting rather than ripping and as new chains seem to be sharpened on a grinder rather than with a file I thought I would get some expert advice on the advantages or disadvantages of both methods.

I've only ever seen it done with a file. I worked for an arborist for a while, and sharpening saws was a multiple-time-a-day thing. If using a grinder would've made it faster, we would've done it. I think that it would be very cumbersome to do it with a grinder.

I'm far from a chainsaw guru though.

Cheers,
Luke

Most chains saw users don't realise they should touch up cutters after about every tank full of mix, and swipe the rakers after every 3 to 4 tanks of mix. By touch up I mean just removing enough metal (2-3 swipes is usually enough) to remove edge glint and maintain a sharp edge. This keeps the chain fron going completely blunt and minimises the load on the power head. Instead what I usually see is folks flogging saws till they are completely blunt, then hand sharpening becomes a chore and a grinder becomes the easiest way.

Now obviously you don't want to constantly have to remove the chain from the bar to put it in a grinder just for a quick touch up so being able to use a file becomes useful.
There are portable alternatives like these hand held chain grinders.
Granberg Grind-N-Joint Hand Held Chain Grinder (12 Volt) | Hand Held Chain Grinders | Chain Grinders & Wheels | www.baileysonline.com
I have one of these and 12V car battery power pack but I have only used it a few times as I find it quicker using a file that to go get the battery pack.

The rakers should be filed with a rounding action so a file has to be used for these.

Overheating a chain using a grinder is not that big of an issue. Cutters are not like chisels or plane blades because they cutters us a thin, hard, chromium coated outer edge over softer (shock absorbing and easier to file) steel which forms the bulk of the cutter. The Cr coat is brittle and when the steel underneath it is filed away the unsupported Cr breaks off and forms a new edge much like breaking a fresh piece of glass does. And just like glass only a very small amount needs to be removed to form a free cutting edge.

BTW even though I use a file I do use a file guide,


I used to use a grinder occasionally to get all the cutters back to the same length and angles, but since using progressive raker setting I don't bother as it's unnecessary if the raker angles are constant.

On advice from my chainsaw shop when faced with the inability to cut straight I use my bench mounted grinder every 4-5 sharpens. No matter how good you are at sharpening by hand he told me, you will always take off more on one side than the other leading to curved cuts. Using the grinder with the stop set up makes sure that all the teeth are the same size...

Originally Posted by david.elliott

On advice from my chainsaw shop when faced with the inability to cut straight I use my bench mounted grinder every 4-5 sharpens. No matter how good you are at sharpening by hand he told me, you will always take off more on one side than the other leading to curved cuts. Using the grinder with the stop set up makes sure that all the teeth are the same size...

I agree that hand filing does result in removing more from one side than the other but all I do to compensate for this is add an extra swipe or two when I file to the right compare to when I swipe to the left. It's also important to move the chain to the same sharpening position rather then moving your legs/arms along the chain. This brings the cutter to the exact same position so the cutters get closer to the same applied file pressure.

Keeping the cutters the exact same length was something I thought of as gospel, but after using progressive raker setting (raker depth proportional to gullet width) for a few years I found worrying about getting the same lengths to be unnecessary and haven't tried too hard to keep the cutters the same length on any of my (20+) chains for the last 9 years. If a cutter starts to look longer than its neighbours I do give it an extra couple of strokes but I don't measure them as suggested in chain manuals.

I am a very intermittent user of my chainsaw; it only comes out once or twice a year now for cutting up trees that have blown over or cutting down palms that have overgrown their positions. Knowing that this was always going to be the end use of my saw I initially invested in a (fairly cheap) electric chainsaw sharper; my reasoning being that accurately sharpening by hand is a skill that takes time to develop that I would never fully achieve. This type of grinder enabled repeat identical sharpenings but at a significant cost; the chain only lasted half a dozen sharpenings before I decided it was too worn and needed replacing.

I then looked at the more traditional type of sharpening using a file and a jig; I was quite taken by the Oregon system but thought the price was a little excessive. Additionally I also knew that there would again be a "running cost"; in this case the files would need to be replaced. It would require setting up before each use and would add to the number of weirdly shaped tools that needed to be stored somewhere.

Finally I stumbled over THIS in the Big Green Shed; I run it in an old GMC rotary tool. The chain stays on the saw and I just move from tooth to tooth with a light touch; this gives me quick sharpening with a degree of repeatability between each tooth that I'm happy with.

I freely admit it's not the best; but taking into account the ease of use, storage and total cost along with how often it is pressed into service it suits my requirements.

Originally Posted by Chief Tiff

I am a very intermittent user of my chainsaw; it only comes out once or twice a year now for cutting up trees that have blown over or cutting down palms that have overgrown their positions. Knowing that this was always going to be the end use of my saw I initially invested in a (fairly cheap) electric chainsaw sharper; my reasoning being that accurately sharpening by hand is a skill that takes time to develop that I would never fully achieve. This type of grinder enabled repeat identical sharpenings but at a significant cost; the chain only lasted half a dozen sharpenings before I decided it was too worn and needed replacing.

It should be possible to get much more than half a dozen sharpenings out of a chain using a grinder,e.g. the tree lopper I do some work for gets around 25 sharpening per chain using a grinder and his operators aren't what I would call that careful..
A friend of mine had a similar problem with a grinder and what I found out was he was not using progressive raker setting so his chains cut less and less the older they go and he attributed that incorrectly to the grinder. As soon as I put him onto progressive rake setting he was able to use his chain until the teeth started dropping off.

I then looked at the more traditional type of sharpening using a file and a jig; I was quite taken by the Oregon system but thought the price was a little excessive. Additionally I also knew that there would again be a "running cost"; in this case the files would need to be replaced. It would require setting up before each use and would add to the number of weirdly shaped tools that needed to be stored somewhere.
Finally I stumbled over THIS in the Big Green Shed; I run it in an old GMC rotary tool.

That's a similar sort of jig I use but with a file (see video). I also have a rotary tool grinder and found the file jig has several advantages over the rotary in that an operator can manually form a much more consistent angle with a longer tool. It also chokes up less frequently because it has a larger surface area and can be cleaned by tapping it onto something hard. In terms of file wear, by lifting the file on the back stroke and keeping it clean I get many months use out of a file that I use regularly and years out of ones that I use infrequently. The files only cost $3 each so its hardly a bank breaker.

The chain stays on the saw and I just move from tooth to tooth with a light touch; .

If you want really consistent results you should move the cutter to the same place on the bar.
Moving the sharpener to the cutter will produce slightly different angles no matter how hard you try to be consistent.

I've always gone for the file, as i find it easier to control a hand tool over grinder, plus its quieter and i didn't always have access to power for a grinder out in the yard.

I picked up one of the Stihl File Guides a few years back, its quick easy and files the throat and the tooth on an angle at the same time allowing it to be consistent.

here is a eBay listing as it has multiple pictures

https://www.ebay.com.au/p/?iid=28250...hn=ps&&&chn=ps

I grabbed it at the Stihl shop, i can't remember the price, but its so easy, i don't mind giving it a quick touch up before use as its so damm quick, nothing as nice as a sharp chain, and i haven't even looked at using single files since i grabbed this file guide.

File every time for me - I've tried all sorts of fancy grinders and powered sharpening tools, and I'm back to files for good. The chain is left on the saw, clamp the bar in a metalworking vice, rotate the chain around as you go. Once you get some muscle memory happening, it doesn't take much longer than the grinding tool, and I get better life out of a file-sharpened chain than any other method. As BobL has commented, better to sharpen light and often than wait until things get really blunt - using this approach, I only check rakers every 2-3 light sharpenings, and file down where required. I've got one of those file holders, but can do a pretty good job these days using the angle mark on each tooth to align the file. We've had professional arborists on the property to do work on bigger trees, and without fail they have a vice arrangement attached to the tailgate of their ute, and sharpen with a file. Mind you, I don't envy them having to touch up the teeth of a Stihl 880 fitted with an extra long bar.....

While 'tis true that hand sharpening can lead to wonky cutting due to uneven tooth length between the two "sides" of the chain (we all have a dominant hand, so file easier facing one way than the other), the way around this is to keep the same foot position, filing in the same direction, and just flip the saw/bar in the vice upside down when it comes time to do the other side. Then you are effectively using the same filing action/strength for all teeth.

Originally Posted by bryn23

I've always gone for the file, as i find it easier to control a hand tool over grinder, plus its quieter and i didn't always have access to power for a grinder out in the yard.
I picked up one of the Stihl File Guides a few years back, its quick easy and files the throat and the tooth on an angle at the same time allowing it to be consistent.
here is a eBay listing as it has multiple pictures

https://www.ebay.com.au/p/?iid=28250...hn=ps&&&chn=ps

I grabbed it at the Stihl shop, i can't remember the price, but its so easy, i don't mind giving it a quick touch up before use as its so damm quick, nothing as nice as a sharp chain, and i haven't even looked at using single files since i grabbed this file guide.

That Stihl file guide is quite expensive, $59 is the RRP, and it will not file the rakers to the optimum depth especially as the chain cutters under go significant more wear.
None of the raker guides file the rakers correctly or to an optimum depth because this varies depending on how worn the cutters are.

The other Stihl) file holder (File holder with round file -) is the same as the base Oregon guide.
Bunnings sell a brand of these called Powerful which are the same thing for $18.

A while back when a local Bunnings was getting rid of all their Oregon stuff I picked up a file guide in every size, 1/8, 5/32, 3/16, 7/32, 1/4 etc for $3 each
I don't quite have chains in all these sizes but using a different size file than recommended by the holder (1/step up or down) enables the hook or side plate filing angle to be subtly varied to help the saw self feed better in different hardness woods.

There are a lot of valid points here, Bob l's point about filing the rakers being one of them. Having to remove the chain from the bar is the big disadvantage for the grinder type of sharpener and being able to sharpen a chain away from a power source is an advantage for the good old hand file. I would probably go with using the file out in the bush and do a quick sharpen as soon as the chain was showing signs of getting dull, then at the end of the day take the chain off, turn the bar over to even out wear and grind the teeth back to something like what the manufacturer made them.
Setting the raker height could be the big problem, I haven't seen one of those little gadgets in a shop for years, I had one, Oregon brand, had it for about 40 years along with a Mobilco Echo saw, but when we lost the house and buildings in a bushfire recently I'm back to starting from scratch.
My real reason for starting this thread was about the profile of the cutting edge of the tooth. A grinder makes a flat face inclined at an angle whereas a file makes a curved face. My question probably gets into the theoretical area but which tooth profile cuts better? My feeling is that the curved cutting edge will cut slightly better than the flat profile but in practice, will it make any difference?

Originally Posted by Old Hilly

. . . Setting the raker height could be the big problem, I haven't seen one of those little gadgets in a shop for years, I had one, Oregon brand, had it for about 40 years along with a Mobilco Echo saw, but when we lost the house and buildings in a bushfire recently I'm back to starting from scratch.

There have been many lengthy discussions on the Arboristsite about how to set rakers and what tools to use.

I haven't used them all but the consensus on Arboristsite is NO single tool sets the rakers correctly especially as chains wear and the cutter get shorter.
There are several tools that come close and one of these is the Carlton File-O-Plate but even that will not produce an optimised raker at the end of the cutters life
In general these tools set cutters too high and make no allowance for wood hardness, width of cut or saw power. Manufacturers do this because their raker setting tools reduce the chance of kickback, produce less vibe and less wear and tear at the expense of slower cutting speeds.

To optimise cutting speeds, in softer, narrower wood with a large saw the rakers can be set A LOT deeper than for opposite situations. In addition swapping between and 7 and 8 pin sprockets further improves optimisation. It doesn't make much difference when cutting a trailer load of fire wood but when chainsaw milling and you have a 1.2m wide cut that is about 3m long you can use every bit of optimisation you can get.

Some old timers, like my dad, use to set rakers by feel - they would swipe the rakers and try the saw to see it made chips rather than dust. If it was still not cutting right they'd swipe them some more till the got it right. if they went too far they'd take a bit off the cutter. Most just used a bit more raker depth all the way through the chain's life but even this can be improved.

Back in 2008-9 I studied the whole cutting process and raker thing in some detail and came up with my own way of setting raker depth which unbeknownst to me is also used by chainsaw racers. The blokes on Arborist site called it Progressive raker setting. Not many chainsaw shops and users know about it but I've mentioned it on this forum many times here and I won't repeat myself about it and will just say that some hundred of chainsaw users on the Arboristsite use it and swear by this method.

My real reason for starting this thread was about the profile of the cutting edge of the tooth. A grinder makes a flat face inclined at an angle whereas a file makes a curved face. My question probably gets into the theoretical area but which tooth profile cuts better? My feeling is that the curved cutting edge will cut slightly better than the flat profile but in practice, will it make any difference?

Firstly we should establish that (unless noodling, i.e. cutting with the grain) chainsaw cutters don't "cut" instead they "Puncture and Tear" wood out of the kerf. Cross grain cutting s more like cross grain chiselling, puncture the wood and then tear out the wood with the chisel. The shape of the cutter is then all about how effectively it punctures the wood.

This is determined by
1) how "pointy" the cutter is,
2) the angle of the leading edge of the cutter, also known as the top plate cutting angle (TPCA) - also know as "hook"
Screen Shot 2017-06-09 at 7.07.22 AM.png

3) And the raker angle - this is raker angle (RA).
rakercorrect.jpg

Whether it's curved or flat contributes to "the way, and to the total extent it punctures", with a curved cutter puncturing the initial part easily and the latter part not so easily but still achieving a greater "total puncture" than an flat sided cutter at the same average angle.
However, flat sided cutting faces can easily achieve the same extent of puncture just by using a slightly greater hook, or RA , or both.

The greater total puncture obtainable with curved cutter edges is obtained at the expense of using a thinner/weaker cutting edge which breaks off the chromium hard edge a little easier meaning the chain goes blunt quicker.
The CS user who sharpens with a file can adjust for that by using a slightly smaller file in a slightly larger file guide.
This lifts the file up in the gullet during the sharpening process and produces a slight steeper edge which does not go as blunt as quickly, and this is exactly what I do.

If you touch up cutters regularly then these issues are less important because having enough "TPCA or "hook" is essential if you want the saw to self feed.
This is self feeding - the saw pulls itself through the cut with just a slight forward slope.
bobsmillingstyle.jpg

Here are some cutters with enough hook.
The top one is taken from Will Mallofs Chainsaw Lumber Making book and the bottom one is mine.
MalloffBobLchain2.jpg

Next we could talks about the raker profile but I see your eyes are glazing over so I will stop there.

As you can tell I have analysed this stuff in some detail.
This is because I am a lazy and want to make things easy for myself, perhaps in contrast to younger fitter types who can make up for these things with a bit more grunt.

Interestingly enough, I was wandering around U-Tube looking at saw sharpening videos and came across one featuring a filing jig from Stihl that sharpened both the tooth and reduced the raker height at the same time. I wandered into my friendly Stihl Shop in Port Macquarie and found that they had these gadgets on the shelf but they were $80.00 each which made me cringe just a little. They seem to have a couple of guide bars that ride on adjacent cutting edges so setting the round file height but then there is a special flat file that rides on the raker and reduces it's height in relation to the adjoining cutters. When you file the tooth you reduce the raker height at the same time. How this would work on a bar with a curved profile I don't know.
It's an expensive gadget. I walked out of the shop with 2 filing jig kits (I have 2 saws with different chain sizes) but now I begin to wonder if that was the wise move. Would I be better served with the more expensive jig and have the chain setup correctly each time it is sharpened?
Are there different raker settings for European softwoods compared to our hardwoods? As the "raker" is really a "depth of cut regulator" would setting them for softwood cause the saw to work harder due to our much harder wood and so cause the chain to wear/stretch faster than it should?
It's raining and the ground is muddy so I might just go for a drive back to Port Macquarie and look a bit closer at those gadgets.

Originally Posted by Old Hilly

Interestingly enough, I was wandering around U-Tube looking at saw sharpening videos and came across one featuring a filing jig from Stihl that sharpened both the tooth and reduced the raker height at the same time. I wandered into my friendly Stihl Shop in Port Macquarie and found that they had these gadgets on the shelf but they were $80.00 each which made me cringe just a little. They seem to have a couple of guide bars that ride on adjacent cutting edges so setting the round file height but then there is a special flat file that rides on the raker and reduces it's height in relation to the adjoining cutters. When you file the tooth you reduce the raker height at the same time. How this would work on a bar with a curved profile I don't know.
It's an expensive gadget. I walked out of the shop with 2 filing jig kits (I have 2 saws with different chain sizes) but now I begin to wonder if that was the wise move. Would I be better served with the more expensive jig and have the chain setup correctly each time it is sharpened?

They sound like the ones Bryn refers to above except they cost $59 on-line. They do lower the rakers every time but not be the right amount and they produce a flat topped raker where I reckon a curved raker top reduces the friction.

Are there different raker settings for European softwoods compared to our hardwoods? As the "raker" is really a "depth of cut regulator"

Not just for softer European woods but even for Aussie woods. It's not just the type of wood, but also the width of the cut, the type of chain and the saw power that determines what the optimum raker setting should be. You are probably not familiar with Marri, but its a much softer old than say Spotted gum. You need to remember I already run my rakers lower than usual anyway so for the same size log and saw, when milling Marri I find can drop the rakers by an extra 5 thou and the big 880 fair flys though the wood, In contrast, in any really wide log (>1.2m) I usually swap to a chain running slight higher rakers and swap from an 8 pin to a 7 pin drive sprocket.

would setting them for softwood cause the saw to work harder due to our much harder wood and so cause the chain to wear/stretch faster than it should?.

Nope because in European softwoods the saw is hardly working so the rakers can afford to be dropped a lot.

It's raining and the ground is muddy so I might just go for a drive back to Port Macquarie and look a bit closer at those gadgets.

See above

Thanks Bob, I missed Bryn's post earlier on. These were the same tool I saw in the shop in Port but at $59 plus $15 postage I would be better off buying locally. The flat file is a special item, noticeably thicker than a common file and with no tang for a handle.
As you say, the depth gauges would be flat-topped but a touch with a file on the leading edge from time to time would fix that problem. The square face of the depth gauge would cause more friction, probably because it would act as a sort of blunt chisel as it dragged through the cut.
One needs to balance the friction demands of the flat-topped depth gauge with the decreases in performance from not lowering the depth gauges. Probably the answer is something more complex but perhaps doing something, even if it isn't quite enough, is better than doing nothing at all?