Chain Sharpening Tips
Chainsaws are high performance, precision wood cutting machines. When you consider the power output of these machines, and the volume of timber they can cut, it's my opinion that no other type of saw comes close to the performance of a chainsaw.
Other power tools can be 'just sharp' - 'a little bit under powered' - 'if you force them they're up to the job'. There's no compromise with chainsaws. The motor must be running at full power and speed. The saw chain must be 'pin' sharp and filed at the correct angles at all times.
A chain is either 'right or rubbish' - there is no in-between.
How to look after your chain!!
From the smallest 10" electric to the largest 48" 120cc petrol chainsaw, from large pitch chipper to small pitch micro bit chain, (with the exception of the filing angles), all chains work the same way.
When a chain is working well, the saw will cut easily, requiring very little force from yourself. The saw must always produce large chips of wood (never saw dust). The time to file the chain is when you need to push the chain to make it cut. If you at this point examine the cutting edge of the chain, it may appear sharp (this is not good enough). IT MUST BE RAZOR SHARP.
If you can see a line of light on the cutting edge THIS IS BLUNT!!!
All saw chain teeth are chrome plated. (A very thin hard chrome plating is bonded to the surface of the cutter). It's this thin hard chrome edge that does all the work (when you lose this edge, the cutting performance rapidly drops off). To keep the chain at its peak, you must keep filing (more than you think).
People always ask how long a chain will last between sharpenings. Somewhere between 30 seconds and 3 months!!!
If you are cutting very near the ground, or rolled muddy logs, (or foolishly roots of a tree) - 30 seconds. Joiners cutting clean planed soft wood - about 3 months.
There are different types of cutter that require different filing angles. On average the usual filing angle is 30 degrees (looking at the top of the cutter).
Looking at the side of the cutter the top part of the cutter would hook forward from the vertical, by about 10 or 15 degrees. This 'hook' makes the chain 'self feeding'. The chain pulls itself into the timber (too much hook and chain will be aggressive and stall, too little hook and you'll have to force the chain to cut).
Different chains require different round files to maintain the cutting angles, 4.00mm, 4.8mm, 5.5mm. You must use the correct file for the chain.
Files are of a good quality and aren't very expensive. BUT as you are filing a hard chrome chain they will not last long (you don't get owt for now't).
You can file a chain 'free hand', but my recommendation would be to use a small 'roller guide'. (See picture at the top of this page).
This device is a small aluminum frame with 2 nylon rollers that clips on the chain. If the file is kept at 90 degrees to the rollers you will get your 30 degree angle. With the right file on the rollers you will get your 10% hook on the cutter.
The time to have your chain professionally ground is when you find that as you cut through the timber the cut curves right or left. This is usually because the filing angles on your right and left cutters are uneven, making your saw cut with a bias. The most usual cause is when you accidentally hit some abrasive material with one side of the saw.
The other time when you need your chain grinding is when the saw only produces sawdust or just tries to burn its way through the wood. This is usually because you've hit some abrasive material and ground the top of the cutter down.
When this happens we need to grind the cutter back to a good chrome edge. This can mean taking out a lot of material. Providing we still leave at least 1mm on the heel of the cutter the chain will still cut.
There is one more thing you need to be aware of regarding the performance of your chain. These are the depth gauges. These are the small pieces of metal that stand up in front of the cutting edge (they are part of the cutter). Looking at the cutter from the side, the height of the depth gauge should be about 0.6mm below the height of the cutter.
The depth gauge governs how much wood is allowed onto the cutter. As the cutter is filed back, the height between the depth gauge and cutter is reduced. Less wood will be cut and the saw will overspeed.
The depth gauges need to be filed down to the correct height (approx. 0.6mm). Depth gauge files and guides are available You must not attempt to file these without a guide (take too much off and the chain will be ruined).
If your depth gauges are filed too low your saw will snatch and stall. Every time we grind a chain, depth gauges are checked and ground.
If you feel my comments aren't clear, or you feel more information is needed, please e-mail or ring. I will be glad to hear from you.