If you’re new to chainsaws, the direction of the chain can cause you problems. Not everyone is a natural-born chainsaw wielder, and the orientation of the chain isn’t a hard-wired base instinct in all of us. Because of that, sometimes, we end up with our chain mounted backward.
Since the chainsaw chain has a specific direction in which it’s intended to travel, putting it backward really affects the cutting ability. The chain’s cutter blades work in one direction, so if your chain is backward, you won’t be able to cut much of anything.
Correct Chainsaw Chain Direction
The chain travels clockwise. It may be easier to see this if you look at the saw from the side. While you’re holding the saw and running it, a clockwise direction means the chain moves away from you when it’s traveling over the top of the bar, then towards you as it’s on the underside.
A chainsaw can be very dangerous— as many as 36,000 people suffer chainsaw injuries each year— so an essential safety feature involves having the chain move away from you. Most of us learned basic knife safety in Boy Scouts and know to cut away from our bodies.
Since a chainsaw is essentially a bunch of knives strung together and driven by an engine, cutting away from your body is extra important, so the chain moves away from you over the top of the bar.
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Which way does the chain go on a chainsaw?
This is easy to learn if you know what to look for. On the top of the chain, you’ve got guides and cutters. In the photo, note two items listed as number one. Both of these are the cutters, and there are two marked because they alternate along the blade, one facing right, the next facing left.
When your chain faces the right direction, the cutters on the top of the bar face forward, toward the end of the bar. Note that the cutters slant upward from back to front. You can also feel that one end of the cutter is sharp since it, you know, cuts.
Item number two is the guide, and there’s one in front of each cutter. It looks kind of like a shark’s dorsal fin. Looking at it that way, you want the shark swimming away from you over the top of the bar. This means that on a correctly mounted chain, the guide’s point points back at you, while the curved side faces forward.
The guide controls the size of the cut but doesn’t do any cutting on its own. It allows for control of how big a bite each cutter takes out of the wood it’s cutting.
Finally, you’ll find the drive links on the underside of the chain. These sit inside the groove on the bar and serve to keep your chain on track and not flying off the bar, which would endanger you and anyone around you. They also have numbers on them indicating things like pitch and gauge. They curve into a point, and that point faces forward when sitting on top of the bar.
How To Replace A Chainsaw Chain
Your chain needs replacing if it’s been damaged or if it’s old enough that you can’t effectively sharpen it anymore. It’s not a complicated process, but since doing it wrong can put your safety at risk, it’s worth knowing what you’re doing rather than just winging it and hoping for the best.
Remove the Chainsaw Case
Most chainsaws come with a chainsaw tool called a scrench. This T-shaped tool has a flathead screwdriver on one end and two wrenches on the other, which is where the portmanteau name comes from.
Two different wrench sizes allow for removing the saw’s spark plug and removing the two nuts holding the casing in place.
To remove the casing:
- Remove both nuts.
- Pull the casing (in the photo, it’s the white plastic polygon) and set it aside.
- Lay it face down so it forms a sort of bowl, then place the nuts in that bowl.
Lose these, and your saw will be useless.
Remove the Chain and Bar
The nuts you just removed held more than the casing in place. They also held the bar in place against the saw’s body, so once the cast comes off, the bar will sag and come out of alignment. There’s a tension adjustment screw, which we’ll deal with more in a bit, that you may need to loosen to remove the bar.
More likely, you’ll be able to pull straight up (assuming the saw is lying on its side and the bar is facing flat-side-up). The chain will be wrapped around the drive sprocket, which impels the chain to move. Depending on your chain’s tension, this can be an easy or not-so-easy process. It may take some wiggling, but essentially, you’ll pull the bar and chain together up off the chainsaw body.
Identify the Cutting Direction of Chain
Keeping in mind what we’ve already discussed, make sure the cutters, when they’re on top of the bar, face toward the end of that bar, and that the pointy end of the drive links, which you’ll fit down into the bar’s groove, face the same direction.
Again, if you put the chain backward, it won’t cut. The motor will move the chain, and you’ll get some metal-on-wood action that will cut via erosion, but there will be a lot of smoke and not a lot of cutting. Be sure to get this right.
Assemble Chain and Bar
Assembly is relatively straightforward but requires a specific order of operation.
- Use the screwdriver end of the scrench to loosen the tension adjustment screw. You’ll see the whole assembly moving forward when you’re turning it in the right direction. Without this step, you may have difficulty getting the bar to fit back into place.
- Stand the bar up on its butt end so its tip is in the air.
- Drape the chain over the bar tip, ensuring that the drive links seat in the groove (and are facing the right direction).
- Fit the links into the groove down the top and bottom sides of the bar. You may find it easier to keep it in place if you pull down on the chain, applying tension to keep the drive links from coming back out.
- Stretch the chain over the drive sprocket (don’t try to do this after putting the bar in place, although in fairness, this step and the next are somewhat two parts of the same step).
- Lay the bar in place, fitting the two bolts into the corresponding holes on the bar.
- Holding the bar steady, fit the casing over the bar and the two bolts.
- Put the nuts back on, but hand-tighten them only. Do not crank them down with the scrench yet.
Tension Chain
Now you’ve put everything back together, but you will need to adjust the chain’s tension, and here’s where the aptly named tension adjustment screw comes into play. You’ll find it located (usually) between the two nuts you just hand-tightened.
Holding the bar in place so it aligns with the body, slowly turn the screw. You’ll see the bar move forward and away from the saw’s body and watch the chain tighten up. Once you’ve put enough tension to keep the drive links seated, but not so much as to tax the engine, then it’s finally time to use the scrench to seat the nuts in place fully. Now go cut some trees.
Can a Chainsaw Chain Be Put On Backwards?
Yes, a chainsaw chain can be put on backward. As we’ve seen, there is a forward and backward direction to chains, and if you’re not paying attention, you can easily mistakenly mount the chain backward.
How do I know if my chainsaw chain is backwards?
When the saw isn’t running, you can look at the cutters. On the top of the bar, the cutters should slant upward, from back to front. If the cutters slant downward to the front of the saw, the chain is on backward.
When the saw is running, you’ll know the chain is backward if you see more smoke than wood chips coming from the saw. Since the cutters are directional, you’ll only be applying metal-on-wood friction if they’re going the wrong way, and that won’t get the job done.
How Tight Should the Chain be on a Chainsaw?
Tighten the chain so that when you pull on it, you can’t pull the drive links all the way out of the bar. The chain can come off the bar while you work if it’s too loose. At best, that’s annoying. At worst, it can be quite dangerous.
Don’t go so tight, though, that the engine has to work harder to turn the chain. There should be some give in the chain, just not so much that the links come unseated.
Why does my chainsaw keep throwing the chain?
The main culprit is a lack of tension. If your chain is too loose, it will come off the bar. Another problem could be with the chain itself. They do a lot of work and suffer a lot of abuse. Eventually, they get stretched. At some point, you won’t be able to tighten the tension adjustment screw enough to apply enough tension, and it will be time for a new chain.
Finally, when the drive sprocket wears out, you won’t be able to keep tension on the chain for any length of time. You can replace drive sockets, so if your saw suffers from this, you don’t necessarily need to buy a brand new chainsaw. But that can be a fun thing to do, so it’s up to you.
