Dremel sell a Sharpening Attachment Kit with an attachment for sharpening chainsaw chains. If you follow the instructions included in the kit you will damage your chain, cause extra wear and tear on your bar and chainsaw, go through more fuel and oil, find cutting more difficult and tiring, have difficulty cutting straight lines, and may put yourself at more risk of kickback and personal injury.
The Dremel A679-02 Sharpening Kit owner’s manual can be found at the product page under “Product Support”. It consists of two manuals in a single PDF — one for Lawn Mower and Garden Tool Sharpening (Model 675) and the other for Chain Saw Sharpening (Model 1453).
If you own the kit and want to learn how to sharpen a chainsaw chain using the chain saw sharpening attachment, then you will probably read that manual.
In the SHARPENING THE CHAIN section, Step 4 instructs you to:
Turn the saw around so that you are looking at the side of the chain bar with the motor to your left. Sharpen the cutter teeth on the far side of the chain, from inside to outside, or away from you, as shown in Figure 6. The guide should be laid flat on the tooth with the 30° index line parallel with the chain.
Repeat the process above to sharpen all of the cutter teeth on the far side of the chain.
Figures 5 and 6 (the one referred to) are reproduced below:
Step 4 and Figure 6 are incorrect.
In Figure 5 you can see that the guide rests on the top plate of the cutting tooth. If you turn the saw around, as instructed in Step 4 and shown in Figure 6, the guide will rest on a depth gauge and not the top plate of the cutting tooth.
The guide is designed to rest exclusively on the top plates of cutting teeth. Depth gauges are lower than top plates, so resting the guide on depth gauges will result in you grinding the cutting corner and side plate too low.
If you consistently grind the left-hand cutting teeth lower than the right-hand cutting teeth the saw chain will not cut evenly through the wood and will pull to one side. This will make it harder to cut straight, increase the amount of pinching and jams on larger diameter logs, and increase the chance of kickback when cutting with the top of the bar.
The sharpener (as currently designed and sold) can only sharpen evenly if both left-hand and right-hand cutting teeth are sharpened from the same side — as per Step 2 and illustrated in Figure 5 — with the motor to the right.
This YouTube video (Chainsaw sharpening. Simple DIY Dremel type rotary tool.) shows the process correctly.
Note that even Dremel’s own videos (e.g. Sharpening a Chainsaw: Dremel Rotary Tool) contradict the manual and show the correct approach (i.e. sharpening from one side), but some (e.g. Sharpening a Chainsaw: Dremel 8200, Sharpening a Chainsaw Blade: Dremel Rotary Tool) make major errors (e.g. resting on depth gauges and grinding at incorrect angles). It does not appear as though anyone who actually knows how to sharpen chainsaw chains was consulted when Dremel made their chain sharpening videos, so it’s probably a good idea not to trust any of them.
1: When sharpening the teeth closest to you exercise a little bit more care — you don’t want to jab the grinding stone into the side plate.
2: Dremel’s sharpening stones (i.e. 453, 454 and 455) wear out and will need to be replaced on a regular basis. When grinding, steady, full-length strokes will evenly wear out the stone and maximise its life. Depending on how much metal you need to grind off each time, the stone may need to be replaced after as few as three or four chains. If your conditions are such that you are wearing out a lot of chains, consider purchasing third-party “diamond chainsaw sharpener burrs” — they are quite cheap to source online and last about three times as long.
3: Due to the direction that rotating tools rotate (i.e. virtually always clockwise, from the point of view of the tool) this attachment will result in metal fragments being thrown downwards and into the chain. Due to the presence of bar and chain oil, some of these fragments will stick in between the links. When you operate your saw, these fragments will cause a small amount of extra wear on the chain, bar and sprockets before finally dislodging. If this sort of thing concerns you, then consider using a set of 2, 3 or even 4 chains, waiting until all of them need sharpening, then sharpening them together and, after they have been sharpened, wash them all clean in a petrol bath. The petrol will dissolve the oil and release the filings, along with any other gunk in the chain, and prevent any of the filings lodging in your bars or sprockets. (Some folks like keeping their chains clean this way regardless of how the chain is sharpened.)