How to change and tension the chain on a chainsaw
Every manufacturer specifies the tooth pitch in the instruction manual. Since the guide bar also has an idler sprocket (designed to provide the necessary tensioning), the sprocket pitch must be the same for both types of chains. Chainsaw chain sprockets can be assembled or solid. The first sprocket has a hub with a gear ring pressed on it. This is how the parts in Champion chain saws are arranged. The complete unit must be removed for replacement, since it is virtually impossible to maintain the factory set interference value at home. And getting a crown separately is also a problem.
On STIHL or Husqvarna chain saws, the replacement ring gear is located directly on the cylinder shaft and is easy to change.
Tooth wear can be identified by the following symptoms:
- There are clearly visible radii in the transition from tooth to socket.
- Tooth width is not uniform in height.
- Chipped metal on top of tooth.
- The inside surface of the bore in the hub has extensive scoring and risks (due to poor lubrication).
- On sprocket bar there is a groove from the guide bar (the chain must be changed, too).
- The chain jams at the initial start.
If at least one of the factors listed above occurs, the drive sprocket needs to be replaced.
Before you start work (especially if the chain saw has been in operation for a relatively short time) it is worth checking the fastening of the saw bar. Tensioner screw has come loose or fastening nuts have come loose. the guide is out of alignment with the longitudinal line of the saw blade. It does not contact with the center, but with the periphery of the teeth in the drive sprocket and causes intensive wear. After tightening the above elements, check the chain saw’s operation: if the play is not eliminated, the sprocket will have to be replaced.
As already mentioned, the sprocket can have a split or pressed ring gear. That’s why the sequence of operations will be different.
For the stationary positioned ring, the following steps are performed in series:
- Dismantling the guard;
- Removing the saw bar along with the chain;
- Disconnecting the clutch from the engine (first, the piston must be locked in place);
- Removing the clutch coupling along with the drum;
- Remove the crown from the drum with an ordinary open-ended wrench (some manufacturers include a puller in their spare parts kit).
Reassemble the assembly in the reverse order. For some models you have to remove the air filter before dismantling the rim.
When disassembling the drive sprocket for a chainsaw that has an interchangeable ring gear, the work order will be much the same, but in the final step only the ring gear needs to be replaced.
After completing the work, check the effectiveness of the replacement. To do this check the tension in the chain: if the chain does not move when the brake is released and you try to pull it in the direction of movement, the chain is too tight and you have to loosen the tensioner a little.
The success of the work is determined by the special repair kit that you have bought for your particular brand of chain saw. If not, you need to know the exact saw size and tooth pitch.
The Husqvarna 137 chain saw has been designed so that all resources maintain maximum performance over time:
- The Auto-Tuning option allows to use the automatic carburetor adjustment.
- If air is sucked in, a secondary filtration takes place that reduces the strain on the filter.
- Vibration damping is due to the LowVib function.
- There’s an easy start option that keeps the Husqvarna 137 chain saw running uninterrupted in all seasons.
- The chain tensioner is located on the side of the body.
- A multipurpose wrench is used for a variety of private adjustments and repairs.
- The sprocket is not only equipped with a. Chain sprocket, sprocket and hub, but also auxiliary hole for receiving lubricant and oil.
This video will show you how to change the chain drive sprocket on your Husqvarna chain saw.
The chainwheel or sprocket is a part that resembles a star. It absorbs engine torque and transmits it to the guide bar and saw chain. It guarantees the rotation of the cutting attachment and the sawing process itself. It operates in automatic mode, which depends on the engine speed.
The clutch drum can be located either outside the chainsaw or inside it, under a separate cover. It has a protective function not only for the sprocket material, but also for the operator who can be injured by the chain while working. In addition to its function of rotating the chain, the drive sprocket prevents the motor system from malfunctioning if the chain jams or stops rotating.
The drum, located at the base of the clutch mechanism, is an integral part of the chain drive system. It is shaped like a star, which is how the chain saw got its name. Depending on the chainsaw, it can be a professional or a home appliance. Because a professional saw is used more often than a domestic appliance, the chain sprocket needs to be replaced regularly. If we talk about domestic tools, it all depends on the amount of work performed and the load on the chain of the device.
Most often the sprocket, sprocket and saw bearing need to be replaced.
In any case, the main reason to replace the sprocket is the chain wear of its teeth. In the case where the device has a monolithic drum, the surface of the chain cuts through it almost completely, which also requires a complete replacement of the entire part. If your chainsaw has a drum with an interchangeable sprocket, you may just replace the sprocket.
Usually in order to remove the sprocket from a chainsaw, many people turn to specialized service centers, but if there is a need to save the family budget, you can perform this work yourself. The activity does not look complicated, but you need to have the necessary parts and tools. The process of changing the sprocket is the same for any model.
Chain orientation and which way to put it on
Chain saw chain looks closely and has teeth that are facing the same direction. That’s why it is easy to find the right direction of the teeth on the guide bar: If you place the chain saw itself on the plane it is in when you work, the row of teeth on top of the guide bar with its sharp edges should be pointing toward the end of the bar. While, the row of teeth, which is located at the bottom of the chainsaw, the sharp edges should face in the opposite direction, towards the drive sprocket.
The chain cannot be slid with its teeth facing inward against the guide bar, it would just not fit on the bar. That’s why it’s necessary to put the chain on the guide bar so that the guide lugs of the sawblade links are turned to the guide bar.
First of all with the same universal wrench we unscrew the headset, the bar, take out the chain, and then remove the air filter.
Next, the spark plug should be unscrewed with the same key that is included in the kit, and then the piston locking mechanism should be installed there so that it can be fixed in the cylinder.
In the wrench set puller, and with the device that came out of it you need to unscrew the coupling in a clockwise direction.
The next step is to remove the clutch drum, this element must be replaced, also the cams and the centrifugal department are subject to wear.
After replacing all the elements with new ones, after a visual inspection of all the elements, you can return all the elements to their places, screwing everything in the reverse order.
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After this procedure, we check the correct installation, and use the saw with a new sprocket and a new chain.
What kinds of chainsaw sprockets there are?
There are two types of sprockets that are used in chainsaws:
The first ones are a single construction of bed, clutch plate, spline and whisk. You can’t get the whisk separately. Such devices are cheaper than collapsible chainsaw sprockets, 5-7 dollars, but they wear out faster and are not economical for replacement. you have to replace the whole construction, not a single part, while the base/plate has almost no wear. Such sprockets are used in budget, Chinese, and Russian chainsaws.
The second one is a double element construction: the base / clutch plate and the whisk. The whisk fits freely into the plate, and can be obtained separately. Sprockets of this type are more expensive than the solid ones, about 20, but they are more profitable at replacement. it is cheaper to replace a single whisk. They are installed in European, premium and professional chainsaws.
The job starts with loosening the saw chain tension. This requires a slotted screwdriver, which should be turned a few full turns counterclockwise the adjusting screw. The latter is accessible through a special hole in the clutch cover (some models have a clutch interlock (emergency brake) on this cover).
Then loosen the two nuts from the bolts fixing the cover and the bar with a ring spanner or ring spanner. Carefully remove the cover.
To shorten the chain, you have to remove one cutting link from the chain. Once this condition is met, it can be adjusted again with the existing tensioning mechanism.
The choice is made visually. Determine the tooth that has been ground down and deformed as much as possible in the process (e.g. “caught” a nail or stud). Then determine the chain pitch to be shortened. There are several ways to do this correctly:
- Using the nameplate on the saw chain;
- by the information on the box (if it is still there);
- Measure with a tape measure or a caliper.
To enter the table, you will need to take one of three measurements. They are exactly equal. Therefore, you choose any one, at your discretion:
Divide the obtained value (in millimeters) by 2. The partial indicates the pitch of your chain in millimeters. Use the table to convert it to inches.
- The second option involves measuring the distance between the five rivets. The resulting value will need to be divided by 4;
- The third option, between seven (divided by six).
The value you get is usually not the same as the one indicated in the table. Therefore choose the table value, as close as possible to the results of your measurement.
If you work with domestic chainsaws of any manufacturer, there is a 95% chance that you will get one of the two values: 8.25mm, which is 0.325″, or 9.30 mm (3/8″). This is the most common pitch for non-professional chainsaws.
It should be prepared in advance. For repair work (if available), it is recommended that you purchase a repair kit. This solution will maximize the quality of your work. For this money you get 30 new connecting links consisting of two parts: the main link (with pins for future rivets) and the counter link (with holes for rivets).
If you can not buy a repair kit, you can use a second-hand chain links and rivets made by yourself. With certain skills, their quality and durability will be comparable with their factory counterparts.
Some craftsmen manage to reuse rivets removed from the chain being shortened. In such cases, however, it is usually necessary to make the walls of the connecting links thinner. This option can therefore be used for short-term sawing operations as a last resort.
- 6 rivets;
- 2 shanks;
- 1 cutting tooth (of your choice);
- 1 kerf limiter.
- It is necessary to cut off 1 and 6 rivets (preferably on both sides) on the section to be removed.
- a procedure that guarantees a minimum probability of damage to the disconnected links is the grinding of the rivet head with a file;
- it is possible to cut it down by means of a hammer, a chisel (preliminary fixation of the chain in a vice);
- use a special attachment on an electric drill, an angle grinder (angle grinder), an emery wheel.
Using mechanisms makes it much faster. However, this solution has two significant disadvantages.
First, the metal, in such processing, significantly heats up, which reduces its strength characteristics (the probability of chain breakage on one of the two remaining links, contacting with 1 or 6 rivets increases).
After removing the external projections the rivet is hammered out of the mounting hole using a drift punch. It is recommended to bend a little the sides of the link.
How to Replace Chain for Mini Chainsaw？
If you need to shorten the original chain of the right brand, there are no questions. And if you have to shorten and install a chain for another model of saw, you need to consider the following.
It is necessary to calculate in advance the number of remaining links so that the number of guide lugs located on the inner side of the saw chain, the spaces between them match the dimensions of the saw’s drive sprocket.
To remove rivets used to connect chain elements, a punch is used, which is a small-sized mechanical press. The main construction elements of this riveting machine are:
There is an eccentric mechanism inside that is actuated by a handle that can be installed on the right or left side of the body. In the home position, it is in the extreme up position (perpendicular to the supporting surface). It is equipped with a special limiter, which allows deviating it from the horizontal by not more than 95%.
Connected to the eccentric is a piston rod with a holder for the punch. As it moves down, it easily squeezes out the rivet without damaging the walls of the link.
It is necessary to make sure that the machine has a set of punches of different sizes (rivets of different diameters are used to connect the elements of the structure of the saw chain, and each rod is designed for only one type).
When working, you should check that the diameter of the holes in the sides of the links coincide with the same size of the puncher.
When laying the chain to be separated on the anvil, it is necessary to avoid contact between the cutting part of the chain and the anvil. Only the shank should be in contact with it.
This question, while seemingly easy to answer, can cause serious problems with implementation. Clearly, riveting is required. But in the free sale, even in specialized stores, they are quite rare. If you are lucky enough to find a repair kit with links matching the chain dimensions of your chainsaw (or electric saw). But the chance of making such a purchase is slim. Therefore, we have to consider alternative options for making rivets. There are not many of them:
Algorithm of chainsaw cutting thread installation
Slow installation of the chain takes no more than 30 minutes, provided that the correct and fixed installation of spare parts. The chainsaw chain installation algorithm consists of 8 steps:
- You need to prepare a flat surface. This avoids misalignment of parts and the chain itself, and minimizes loss of fasteners. First lay the guide bar and chain parallel to each other.
- Removing the sprocket guard. On older models, the sprocket guard is a wing nut that is easy to unscrew. For the newer models of chainsaws you’ll need a wrench (most often 10).
- The chain saw drive sprocket at the base of the guide bar should be unscrewed all the way to the right.
- On each fixing groove of the guide bar the links are placed in sequential order (link by link). The chainsaw chain is mounted on top of the guide bar so that the bar is always on top, while the chain is on the bottom.
- Put the guide bar and the chain on the drive sprocket.
- Replace the sprocket cover. During installation it is important to make sure that the sprocket itself is straight and free of play.
- Let’s check the position of the guides, which must be in a special groove.
- Check that the chain is firmly fixed in the bar and in the chainsaw.
After this procedure is complete, all that’s left is to tension the chain itself. But before we go to this procedure, we should make sure that the chain is in the correct position. Otherwise you will either have to repeat the algorithm repeatedly (up to disconnecting the tire and chain).
How to: Change a Chain on a Husqvarna Chainsaw. ( Model 445 )
How to tension the chain on a chainsaw
Before you tighten the chain, check the manual. it says exactly how and with what you need to tighten it. Depending on the model, the tension may vary. If this manual is not available or is in a different language, use our suggestions. They will be below.
Let’s consider two types of chain saws. classic and with a knob for tension adjustment.
- Take the wrench from the kit, its shape resembles the letter T. The spanner has two working parts: one for undoing the nuts and the other for turning the tensioning screw.
- Loosen the cover nuts first, but do not unscrew them.
- Use the other hand (screwdriver) to turn the tensioning screw. It is located near the nuts.
- Turn the screw clockwise until the chain slack at the bottom is about five millimeters.
- Tighten the nuts.
These models are less popular and are only used on more expensive machines. There is a knob on the side of the cover that will tighten or loosen the chain when you turn it. Clockwise to tighten, counterclockwise to loosen. Again, make sure the slack is no more than 5 millimeters.
Before you get to work, you should check again how the chain is tensioned:
There should be ±5 millimeters of slack in it. Check it with your hand to see how it feels. Make sure you stroke lightly.
Worst case if you overtighten the chain. Loosely tensioned chains quickly come off and become noticeable. Overtightened chains make themselves felt not immediately. you may not even notice the difference for a long time, but the wear of the parts will increase.
How to correctly put the chain on the chainsaw: direction
When considering how to correctly put the chain on the chainsaw, let us note the point that the modern version of the tool has a special setting wheel. Due to it, the procedure is greatly simplified. Among its features are the following points:
- Considering how to put the chain on the chainsaw correctly, we note that first it is necessary to prepare an even surface. This prevents damage to the tool. After that, the main part of the tool, the bar and the chain are laid out separately.
- The next step is to remove the protection, which is designed to protect the sprocket. In most cases it is fixed with an ordinary wing nut.
- On the bar the tensioning sprocket turns to the right as far as it will go. This is where the tool is installed.
- Then the chain is gradually slipped over the fixing element. Quite a common question is which side of this element is put. Installation begins at the top, with the chain rotated so that the bar is over. Only wear thick gloves which can withstand the cutting edge. The cutter on the end face must be placed forward.
- Both elements are put on the sprocket.
- The next step is to reattach the sprocket cover. It is important to make sure that the pins are in line with the holes. Incorrect fixation can cause rattling or other problems.
- Make sure that the guides are in the special groove.
- Visually inspect the chain after it is securely fastened.
The next step is to directly check that the chain has not been over tightened. To do this, release the chain brake and pull it along the line of motion. Checking is carried out only with special gloves.
In general it can be said that the procedure under consideration is quite simple to perform and does not require special tools. However, not all chain saws are as easy to service as the above models.
Necessary tools and equipment for tightening the chain on a chainsaw
In order to properly tighten the chain, you need to know some simple mechanisms and simple tools. On STIHL chain saws, tensioning is easy with the integrated chain tensioner. This method is very simple and is very fast. To tighten or adjust the degree of slack in the chain, the manufacturer recommends doing the following
- Using a wing nut, unscrew the sprocket cover;
- Turn the adjusting wheel to determine the required length of chain, tightening it to the required degree;
- the sprocket cover is closed again and the chain is firmly secured to the bar.
If it is impossible to tension the chain of a chainsaw with a built-in mechanism, use such tools (by the example of a Sparky electric saw):
- angle grinder with metal disk;
- Allen wrench, 5 mm in diameter;
- piece of wire;
- a wooden stick or a sturdy splinter;
- flat screwdriver.
After de-energizing the electric saw, unscrew the screws with an allen key, remove the housing cover, unscrew the tensioning screw with a screwdriver and remove the stem nut. The side of the screw adjacent to the body of the saw is ground with a disk. The saw is then reassembled in the reverse order. The hex wrench is needed to clean sawdust from the body.