What is the best way to measure chainsaw bar length? The most common and practical method to measure chainsaw bar length is to count the number of drive links on the chain that rides on the bar, and then add two inches to that number.
So, how do you figure out the correct chainsaw bar size for your saw, or when you need a chainsaw bar replacement? It’s not as tricky as it might seem! Knowing your chainsaw bar measurement is super important for safety, performance, and making sure your saw runs right. This chainsaw bar length guide will walk you through everything you need to know, from simple counting to deciphering numbers stamped on the bar.
Why Knowing Your Chainsaw Bar Size Matters
Your chainsaw bar is the long metal piece that guides the cutting chain. It’s like the sword for your power tool! The length of this bar directly impacts how efficiently and safely you can cut wood.
- Cutting Capacity: A longer bar lets you cut through bigger logs and thicker trees in one pass.
- Balance and Handling: The bar length affects how the chainsaw feels in your hands. A longer bar can make the saw heavier and less maneuverable, especially for lighter saws.
- Engine Power: Your chainsaw’s engine is designed for a specific bar length. Putting on a bar that’s too long can strain the engine, reduce cutting speed, and even damage the saw.
- Chain Compatibility: The bar length dictates the type of chain you need, including its pitch and gauge.
Common Methods for Chainsaw Bar Measurement
There are a few ways to get the right chainsaw bar measurement. We’ll cover the most reliable ones.
Method 1: Counting Drive Links (The Most Reliable Method)
This is the go-to method for accurate chainsaw bar sizing. It’s simple, effective, and works for almost any chainsaw.
What are Drive Links?
Drive links are the parts of the saw chain that sit in the groove of the guide bar and are driven by the sprocket. They are the small metal tabs that extend downwards from the chain.
How to Count Drive Links:
- Remove the Chain: Make sure your chainsaw is off and cool. Take off the chain cover. Carefully unhook the saw chain from around the bar and the drive sprocket.
- Lay the Chain Flat: Spread the chain out on a flat surface.
- Count the Drive Links: Look at the chain and count each individual drive link. These are the pieces that fit into the bar’s groove. Count them one by one until you’ve gone all the way around.
- Add Two Inches: Once you have your drive link count, add two inches to that number. This is the standard way chainsaw bar length is referred to in inches.
Example:
If you count 50 drive links on your chain, the chainsaw bar length is 20 inches (50 drive links + 2 inches = 20 inches).
Why does this work?
Manufacturers standardize bar lengths based on the number of drive links. A 20-inch bar will typically use a chain with 72 drive links (since 72/3 = 24, and 24 * 2 = 48, plus 2 for the bar length, it comes to 20 inches). The “plus two inches” is a convention, not a literal measurement of the bar’s metal length, but it’s how the industry refers to them.
Method 2: Checking the Stamped Number on the Bar
Many chainsaw bars have a number stamped onto them, usually near the base where the bar connects to the chainsaw body. This number often indicates the bar length.
How to Find the Stamped Number:
- Locate the Bar: With the chain removed, inspect the guide bar.
- Look Near the Base: Check the area where the bar mounts to the chainsaw’s powerhead. You might see numbers etched or stamped into the metal.
- Interpret the Number: This number is usually the nominal bar length in inches (e.g., 16, 18, 20).
Important Notes:
- Not Always Present: Some older bars or aftermarket bars might not have this marking.
- Different Markings: Sometimes, the number might refer to something else, like the chain pitch or gauge. Always cross-reference with the drive link count if possible.
Method 3: Measuring the Bar Directly (Less Common for “Length”)
While you can physically measure the metal bar, this isn’t the standard way to determine the “bar length” for purchasing a replacement or chain. The industry standard is based on drive links and nominal length.
How to Measure Directly:
- Remove the Bar: Take the bar off the chainsaw.
- Use a Measuring Tape: Measure from the tip of the bar (the nose) to the point where the bar enters the chainsaw body (the heel).
- Convert to Inches: Ensure your measurement is in inches.
Why this isn’t ideal:
The actual metal length might be slightly different from the nominal bar length. For instance, a 20-inch bar might measure 20.5 inches from tip to heel. Relying on this direct measurement can lead to getting the wrong size chain or bar. The drive link count is much more precise for compatibility.
Deciphering Chainsaw Bar Markings: Beyond Length
Besides the length, other numbers and symbols on your chainsaw bar are crucial for choosing the correct chain and for overall chainsaw bar identification.
Chain Pitch
- What it is: The distance between the drive links of your saw chain. It’s measured from the center of one rivet to the center of the next, then divided by two.
- Common Pitches: 3/8 inch, .325 inch, 1/4 inch.
- Where to find it: This is often stamped on the guide bar near the chain brake or at the base of the bar. It might be written as “.375″ for 3/8” or “.325”.
- Why it matters: The pitch of your chain must match the pitch of your drive sprocket and the groove on your guide bar. Using the wrong pitch will cause poor cutting, damage your saw, and can be dangerous.
Chain Gauge
- What it is: The thickness of the drive links that sit in the bar’s groove.
- Common Gauges: .050 inch (1.3 mm), .058 inch (1.5 mm), .063 inch (1.6 mm).
- Where to find it: This is also usually stamped on the guide bar, often near the pitch. It might be written as “.050” or “.063”.
- Why it matters: The gauge must match the groove width on your guide bar. A chain that’s too loose in the groove can jump off, and one that’s too tight will bind and wear out quickly, potentially damaging the bar.
Drive Link Count
- What it is: As discussed earlier, this is the number of drive links on the chain that fit into the bar.
- Where to find it: You have to count them yourself.
- Why it matters: This is the most direct way to determine the correct nominal bar length.
Chainsaw Bar Sizing: Matching Bar to Saw
Knowing your chainsaw bar size isn’t just about the number; it’s about making sure that number is appropriate for your chainsaw model and engine.
Matching Bar Length to Your Chainsaw’s Power
Chainsaw manufacturers design their saws with specific bar length ranges in mind.
- Small Saws (e.g., 10-14 inch bars): Typically have smaller engines (around 30-40cc). They are lighter, more maneuverable, and suited for light-duty tasks like trimming branches, limbing, and cutting smaller trees.
- Mid-Size Saws (e.g., 16-20 inch bars): Common for homeowners and property owners (around 40-60cc). They offer a good balance of power and usability for felling medium-sized trees and processing firewood.
- Large Saws (e.g., 20+ inch bars): Built for professionals and serious arborists (60cc and up). These are powerful, heavier, and designed for felling large trees and demanding work.
Consequences of Mismatching:
- Bar Too Long:
- Engine Strain: The engine has to work harder to drive a longer chain, leading to overheating and potential damage.
- Reduced Cutting Speed: The saw will cut slower because the engine can’t maintain chain speed effectively.
- Increased Kickback Risk: A longer bar can increase the leverage the saw has, making kickback more severe.
- Bar Too Short:
- Inefficiency: You won’t be able to cut as efficiently through larger wood.
- Can Damage Bar Mount: While less common, a significantly shorter bar might not be ideal for the overall balance and stress distribution on the powerhead.
Checking Your Chainsaw’s Manual
The best place to find out the recommended bar length for your specific chainsaw model is in the owner’s manual. It will list the compatible bar lengths, chain pitch, and chain gauge.
Looking Up Your Chainsaw Model Online
If you don’t have the manual, search online for your chainsaw’s make and model number. Many manufacturers provide digital manuals or specifications on their websites.
Chainsaw Bar Replacement: When and How
Guide bars don’t last forever. They wear down over time, and replacing them is a normal part of chainsaw maintenance.
Signs Your Bar Needs Replacing:
- Groove Wear: The groove where the chain runs can get wider or develop burrs. This is often the most common wear.
- Bar Nose Damage: The sprocket at the tip of the bar can wear down or get damaged.
- Warping: The bar can become bent or warped due to stress or improper tensioning.
- Uneven Wear: If you don’t flip the bar periodically, one side will wear out faster.
How to Replace a Chainsaw Bar:
- Safety First: Ensure the chainsaw is off, cool, and in a stable position. Wear gloves.
- Remove the Chain: Loosen the bar nuts and remove the chain.
- Remove Old Bar: Unscrew the bar nuts completely and carefully lift off the old guide bar. Note how the chain catcher (a small metal piece that stops the chain if it breaks) is positioned.
- Clean the Area: While the bar is off, clean the sprocket nose and the area around the bar mount.
- Prepare New Bar: Make sure your new bar has the correct pitch, gauge, and drive link count for your saw. Some bars require you to transfer the chain catcher from the old bar.
- Install New Bar: Place the new bar onto the mounting studs, ensuring it’s correctly oriented and the chain catcher is in place.
- Install New Chain: Loop the new chain around the bar nose sprocket and the drive sprocket.
- Tension the Chain: Adjust the tensioner screw (usually on the side of the bar mount) until the chain is snug but can still be pulled by hand around the bar. The drive links should not hang down from the bar.
- Tighten Bar Nuts: Tighten the bar nuts securely.
- Final Tension Check: With the bar nuts tight, check the chain tension again. Run the saw for a few seconds (without cutting) to seat the chain, then re-tension if necessary. The chain should be tight enough not to sag but loose enough to move freely by hand. A good rule of thumb is that it shouldn’t sag when the bar is held horizontally.
Chainsaw Bar Length Calculation and Charts
While direct “chainsaw bar length calculation” isn’t a complex math problem, it’s about applying the drive link count rule. However, having a chainsaw bar length chart can be helpful for quick reference or when you’re unsure of your drive link count.
Example Chainsaw Bar Length Chart:
| Drive Links | Nominal Bar Length (inches) |
|---|---|
| 44 | 12 |
| 52 | 14 |
| 56 | 16 |
| 64 | 18 |
| 72 | 20 |
| 80 | 22 |
| 84 | 23 |
| 88 | 24 |
Note: This is a general chart. Actual drive link counts can vary slightly between manufacturers for the same nominal bar length, which is why counting is always best.
Measuring Chainsaw Bar Diameter (Not Standard for Bar Length)
You might have heard about “measuring chainsaw bar diameter.” This usually refers to the diameter of the roller nose on the bar, which impacts chain fitment and wear. However, this is not how you determine the bar length. Bar length is always determined by the drive link count or the nominal length marking.
Frequently Asked Questions (FAQ)
Q1: Can I put a longer bar on my chainsaw?
A1: While technically possible, it’s generally not recommended unless your chainsaw’s manual specifically states it’s an option. A longer bar can strain your engine, reduce cutting performance, and increase the risk of kickback. Always check your chainsaw’s specifications.
Q2: How often should I replace my chainsaw bar?
A2: This depends on usage and maintenance. A good rule of thumb is to replace the bar when the groove depth is worn by more than half, or when the nose sprocket is significantly worn or damaged. Many users replace the bar every 2-3 chains, or when they notice a decrease in cutting performance and increased chain wear.
Q3: What is the difference between a round nose and a sprocket nose bar?
A3: A round nose bar has a solid, curved tip and is less prone to kickback but can be slower. A sprocket nose bar has a replaceable sprocket at the tip, which reduces friction and wear, leading to faster cutting and easier maintenance. Most modern bars are sprocket nose.
Q4: My bar has a number like “3/8 .050” stamped on it. What does that mean?
A4: This indicates the chain pitch (3/8 inch) and the chain gauge (.050 inch). You need a chain that matches these specifications, and a guide bar with the correct pitch and gauge groove to fit it.
Q5: Can I use a bar from a different brand of chainsaw on mine?
A5: Yes, but only if the mounting system, bar length, chain pitch, and chain gauge are identical. It’s always best to stick to bars designed for your specific chainsaw model for optimal performance and safety.
Q6: What happens if my chain is too loose or too tight?
A6: A loose chain can derail, causing damage to the saw and posing a serious safety hazard. A tight chain will cause excessive wear on the chain, bar, and drive sprocket, leading to premature failure and reduced cutting efficiency. Proper tension is key.
By following this comprehensive guide, you should now have a clear picture of how to measure your chainsaw bar length and make informed decisions about chains, bars, and overall saw maintenance. Happy cutting!