What is chainsaw chain size? Chainsaw chain size is determined by three key measurements: pitch, gauge, and the number of drive links. You can also determine compatibility by checking your saw model, bar length, and the specific chain type needed.
Choosing the correct chainsaw chain size is vital for your saw’s performance, safety, and longevity. Using a chain that’s too large or too small can lead to inefficiency, damage to your saw, and dangerous kickback. This guide will walk you through everything you need to know to accurately determine your chainsaw chain size.
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The Three Core Measurements: Pitch, Gauge, and Drive Links
The fundamental aspects that define a chainsaw chain’s size and compatibility are its pitch, gauge, and the number of drive links.
Fathoming Pitch
Pitch refers to the distance between the drive links. It’s a critical measurement because it must precisely match the pitch of your saw’s drive sprocket and the nose sprocket on the guide bar. If the pitch doesn’t match, the chain won’t engage properly with the sprockets, leading to poor cutting performance and rapid wear.
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How is Pitch Measured?
Pitch is measured from the center of one drive link rivet to the center of the next drive link rivet, then divided by two. Chainsaw chains typically come in standard pitches such as 3/8-inch, .325-inch, and 1/4-inch. Larger, more powerful saws often use larger pitches (e.g., 3/8-inch or .404-inch), while smaller saws use smaller pitches. -
Finding Your Saw’s Pitch:
The easiest way to find your saw’s pitch is to look for it stamped directly onto your guide bar. Usually, it’s found near the base of the bar where it attaches to the saw. If it’s not there, consult your chainsaw’s owner’s manual. If all else fails, you can measure it yourself by taking a measurement from the center of one drive link to the center of the next, and then dividing by two. You’ll need a ruler or caliper for accuracy.
Gauging the Gauge
The gauge of a chainsaw chain refers to the thickness of the drive links, which are the parts of the chain that sit inside the groove of your guide bar. The gauge of the chain must match the groove width of your guide bar for proper fit and function.
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How is Gauge Measured?
Gauge is measured by the thickness of the drive link. Common gauges are .050-inch, .058-inch, and .063-inch. A chain with the wrong gauge will either be too loose in the bar groove (if the gauge is too small) or too tight and won’t feed correctly (if the gauge is too large). -
Identifying Your Saw’s Gauge:
Similar to pitch, the gauge is often stamped on the guide bar, usually near the pitch. Look for numbers like “050” or “058.” If you can’t find it on the bar, your owner’s manual is the next best source of information. If you need to measure it, you can use a caliper to measure the thickness of a drive link.
Counting Drive Links
The number of drive links is the exact count of the individual links on the chain that engage with the sprocket and sit within the guide bar’s groove. This number is crucial for ensuring the chain is the correct length for your guide bar.
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Why Drive Links Matter:
The number of drive links dictates the total length of the chain. If you have too few drive links, the chain won’t be long enough to complete a full loop. If you have too many, the chain will be too long, and the tensioning mechanism won’t be able to take up the slack, resulting in a loose chain that can easily derail or cause damage. -
Determining Your Drive Link Count:
The most straightforward method is to count them! Remove the old chain and count the number of drive links that ride in the groove of the guide bar. Alternatively, you can find this information in your owner’s manual. Some chain packaging will also specify the number of drive links.
Other Crucial Factors for Chain Selection
Beyond the core measurements, several other factors play a significant role in ensuring you select the right chainsaw chain.
Bar Length Considerations
The bar length of your chainsaw is the measurement from the tip of the bar to the point where it meets the saw’s powerhead. While bar length doesn’t directly dictate the chain’s pitch or gauge, it directly relates to the required number of drive links. A longer bar requires a longer chain with more drive links.
- Matching Chain to Bar Length:
Chainsaw manufacturers design their bars for specific chain lengths. For instance, a 16-inch bar will typically use a chain with a specific number of drive links, while an 18-inch bar will use a longer chain with more drive links. Always ensure the chain you purchase is designed for the specific bar length you are using. For example, a 20-inch bar will require a different chain length than a 16-inch bar, even if they share the same pitch and gauge.
Decoding Chain Type
Chainsaw chains are not all the same; they come in various types designed for different cutting applications and chain saw characteristics. The chain type impacts its cutting speed, aggressiveness, vibration, and durability.
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Common Chain Types:
- Full Chisel: These chains have square-cornered cutters for fast, aggressive cutting. They are ideal for professional loggers and experienced users who need to cut through hard or frozen wood efficiently. However, they are more prone to kickback and require more frequent sharpening.
- Semi-Chisel: These chains have rounded-corner cutters. They offer a good balance between cutting speed and durability, making them suitable for a wide range of users and applications. They are less aggressive than full chisel but also less prone to kickback and stay sharper for longer.
- Skip Tooth (or Semi-Skip): These chains have every other drive tooth removed. This spacing allows for better chip clearance, which is beneficial when cutting softwoods or in dirty conditions. They tend to cut slower but can prevent chain jamming in challenging situations.
- Low Profile: These chains are designed for smaller chainsaws and offer reduced kickback potential. They typically have smaller cutters and are less aggressive than standard chains.
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Selecting the Right Type:
Consider what you’ll be cutting. For general yard work and occasional use, a semi-chisel chain is usually a good choice. For demanding professional work, full chisel might be preferred. If you’re cutting a lot of dirty wood or softwoods, a skip tooth chain could be advantageous.
The Role of the Sprocket
The sprocket is the toothed wheel that engages the chain and is driven by the engine. The sprocket on the clutch drum (drive sprocket) and the sprocket at the tip of the guide bar (nose sprocket) must match the pitch of your chain.
- Sprocket Compatibility:
If you replace your drive sprocket, ensure the new one matches your chain’s pitch. Similarly, if you replace your guide bar’s nose sprocket, it must also match the chain pitch. Some guide bars have interchangeable sprockets, while others have them permanently fixed.
Teeth Count and Its Impact
The teeth count, referring to the number of cutting teeth on the chain, influences how quickly the chain cuts. While not a direct sizing factor in terms of pitch or gauge, it’s a characteristic that defines a specific chain and is usually tied to a particular bar length and saw.
- Teeth Count and Cutting Speed:
A chain with more teeth might cut slightly faster as there are more cutters working. However, this also means more friction and potentially faster dulling if not properly maintained. The number of teeth is intrinsically linked to the total length of the chain (number of drive links) and the pitch.
Cutters: The Business End of the Chain
The cutters, also known as teeth, are the sharp edges that do the actual cutting. They are designed with specific angles and shapes based on the chain type and intended application.
- Cutter Geometry:
Different cutter geometries affect how the chain bites into wood. Full chisel cutters have a sharp, 90-degree angle, while semi-chisel cutters have a more rounded, 80-degree angle. The sharpness and condition of the cutters are paramount for efficient cutting.
Understanding Kerf
The kerf is the width of the cut made by the chainsaw chain as it passes through the wood. The kerf is determined by the width of the chain’s cutters.
- Kerf and Cutting Efficiency:
Chains with a narrower kerf (thinner cutters) require less power to cut through wood and produce less sawdust. This can be beneficial for smaller chainsaws or when making many cuts. However, narrower kerf chains are generally less durable and more prone to damage from hitting foreign objects. Chains with a wider kerf are more robust but require more power. The gauge of the chain is directly related to its kerf.
How to Find the Right Chain for Your Saw
Now that we’ve covered the key measurements, let’s look at practical ways to find the correct chain.
Method 1: Consult Your Owner’s Manual
This is by far the most reliable method. Your chainsaw’s owner’s manual will specify the exact pitch, gauge, and the recommended chain length (often in number of drive links) for your specific saw model. It may also suggest preferred chain types.
Method 2: Inspect Your Current Chain and Bar
As mentioned previously, most of this information is stamped directly onto the guide bar.
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Locate Markings on the Guide Bar:
- Pitch: Look for a measurement like “3/8” or “.325”.
- Gauge: Look for a measurement like “050” or “058”.
- Drive Links: While not always stamped, knowing the bar length and model can help you find the corresponding drive link count for chains made for it.
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Inspect the Old Chain:
If your old chain is still intact, you can count its drive links. You can also examine its cutters for wear and damage to get an idea of what might be needed for a replacement.
Method 3: Identify Your Saw Model and Manufacturer
If you know your chainsaw’s manufacturer and exact model number, you can often find replacement chain information online through the manufacturer’s website or by contacting their customer support. Many retailers also have online chain selectors where you input your saw model to find compatible chains.
- Example: If you have a “Stihl MS 250” or a “Husqvarna 450 Rancher,” searching for “Stihl MS 250 chain size” or “Husqvarna 450 Rancher replacement chain” will yield precise results.
Method 4: Measure if Necessary
If you can’t find the information through the above methods, careful measurement is your last resort.
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Measuring Pitch:
- Lay the chain flat.
- Measure from the center of one rivet to the center of the next rivet.
- Divide that measurement by two.
- Convert to inches (e.g., 19 mm / 2 = 9.5 mm; 9.5 mm is roughly 3/8 inch).
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Measuring Gauge:
- Use a caliper to measure the thickness of a drive link.
- Ensure it’s the part that sits within the guide bar groove.
- Convert to inches (e.g., 1.3 mm is approximately .050 inch; 1.5 mm is approximately .058 inch).
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Counting Drive Links:
- Remove the old chain.
- Count the number of metal tabs (drive links) that fit into the guide bar groove.
Common Chainsaw Chain Size Combinations
Here are some typical combinations you might encounter, though variations exist:
| Saw Model Example | Bar Length | Pitch | Gauge | Drive Links (Approx.) | Chain Type (Common) |
|---|---|---|---|---|---|
| Stihl MS 170 / MS 180 | 16″ | 3/8″ LP | .043″ | 52 | Low Profile Semi-Chisel |
| Husqvarna 350 / 440 | 18″ | .325″ | .050″ | 64 | Semi-Chisel |
| Stihl MS 250 / MS 261 | 16″-20″ | 3/8″ | .050″ | 56-60 | Full/Semi-Chisel |
| Husqvarna 455 Rancher | 20″ | 3/8″ | .058″ | 72 | Full/Semi-Chisel |
| Stihl MS 462 / MS 500i | 25″ | 3/8″ | .063″ | 70-74 | Full Chisel |
| Husqvarna 372XP / 390XP | 24″-28″ | .404″ | .063″ | 84 | Full Chisel |
Note: “LP” in 3/8″ LP refers to Low Profile, a narrower pitch for smaller saws. “.043” is also sometimes referred to as 1.1mm.
What Happens if You Use the Wrong Chain Size?
Using a chain with the incorrect pitch, gauge, or length can cause a variety of problems:
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Incorrect Pitch:
- Too Small: The chain will not engage properly with the sprocket, leading to slipping, poor cutting, and excessive wear on the chain and sprocket.
- Too Large: The chain will not fit onto the sprocket or guide bar groove, making it impossible to mount. If forced, it can cause catastrophic damage.
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Incorrect Gauge:
- Too Small: The chain will be loose in the guide bar groove. This can cause it to jump off the bar, leading to damage and dangerous kickback.
- Too Large: The chain will be too tight in the guide bar groove, causing excessive friction, heat buildup, and making it difficult or impossible for the saw to cut effectively. It can also damage the bar and chain.
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Incorrect Length (Drive Links):
- Too Short: The chain will not meet properly, and the tensioner will not be able to take up the slack. The chain will not engage the sprockets fully.
- Too Long: The chain will be loose even when the tensioner is engaged. This can cause it to derail, damage the saw, and lead to kickback.
Maintaining Your Chainsaw Chain for Optimal Performance
Once you have the correct chain, proper maintenance is key to its lifespan and your saw’s performance.
Sharpening Your Chain
Sharp cutters are essential for efficient and safe cutting. Dull chains require more force, put a strain on your saw, and increase the risk of kickback.
- Filing Techniques: Use a round file of the correct diameter for your chain’s pitch. File at the recommended angle (usually 25-35 degrees) on each cutter. Maintain consistent strokes and depth.
- Depth Gauges: The depth gauges (bumpers) that precede each cutter help control how much wood the cutter removes. If they are too high, the chain will grab and cut aggressively. If they are too low, the chain will cut slowly. They need to be filed down periodically to maintain the correct height relative to the cutter.
Oiling Your Chain
Proper lubrication is crucial to reduce friction and heat, which extend the life of your chain and guide bar.
- Automatic Oiling System: Most chainsaws have an automatic oiler that feeds oil from a reservoir to the chain and bar. Ensure the oil reservoir is full before each use.
- Manual Oiling: If your saw doesn’t have an automatic oiler, or if you’re using a manual oiler, ensure you apply oil frequently to the chain and bar while cutting.
- Correct Oil Type: Use bar and chain oil specifically designed for chainsaws. Motor oil is not suitable.
Tensioning Your Chain
Correct chain tension is critical for safety and performance.
- Checking Tension: A properly tensioned chain will be snug against the bar but should still be able to be pulled around by hand (with gloves!). There should be no sag on the underside of the bar. When the chain is correctly tensioned, a few teeth on the bottom of the bar should be visible.
- Adjusting Tension: Use your saw’s tensioning screw (usually on the side or front) to adjust the tightness. Always loosen the bar nuts slightly before adjusting the tension. Retighten the bar nuts firmly after tensioning.
Frequently Asked Questions (FAQ)
Can I use a different pitch chain on my saw if it fits?
No, you should never use a chain with a different pitch than what your saw is designed for. The pitch must match the drive sprocket and guide bar sprockets precisely for safe and effective operation. Using the wrong pitch can cause severe damage and is a major safety hazard.
What does “low profile” mean for a chainsaw chain?
“Low profile” refers to chainsaw chains designed for smaller, less powerful chainsaws. They typically have a narrower pitch (like 3/8″ low profile or 1/4″) and thinner cutters. This design reduces the likelihood of aggressive kickback and requires less power to cut, making them safer and more efficient for their intended saws.
How often should I replace my chainsaw chain?
Chainsaw chains need to be replaced when they become too worn to be sharpened effectively. Signs include:
* The chain requires frequent sharpening.
* The cutters appear significantly smaller or deformed after sharpening.
* The drive links or cutters are cracked or broken.
* The chain consistently sags even when properly tensioned.
* You notice a significant decrease in cutting performance despite proper sharpening.
What is the purpose of the different cutter shapes on a chainsaw chain?
The different cutter shapes (full chisel vs. semi-chisel vs. skip tooth) are designed for different cutting characteristics. Full chisel cutters are aggressive and fast but dull quicker and are more prone to kickback. Semi-chisel cutters offer a balance of speed, durability, and reduced kickback. Skip tooth chains are designed for better chip clearance, ideal for softwoods or dirty conditions.
Does the number of teeth on a chain matter for sizing?
While the number of teeth (cutters) is a characteristic of a specific chain, it’s not a primary sizing factor like pitch or gauge. The number of teeth is directly related to the chain’s overall length (drive links) and pitch. For instance, a 72-drive link chain at 3/8″ pitch will have a certain number of cutters, and a 64-drive link chain at .325″ pitch will have a different number of cutters. You need to ensure the chain matches your saw’s pitch, gauge, and length requirements.
By carefully considering pitch, gauge, drive links, and matching them to your saw model and bar length, you can confidently select the right chainsaw chain for efficient, safe, and productive work. Always prioritize safety and consult your owner’s manual for the most accurate specifications.