Image Source: i.ytimg.com
How to Measure Chainsaw Bar Length: A Comprehensive Guide
How do you measure the bar length on a chainsaw? You measure a chainsaw bar by looking at the number of drive links on the chain that fits it and then converting that to inches, which is the standard measurement for chainsaw bars.
Choosing the right chainsaw bar length is crucial for optimal performance and safety. Whether you’re a seasoned arborist or a homeowner tackling a weekend project, knowing how to accurately measure and select the correct bar size can make all the difference. This guide will walk you through everything you need to know about chainsaw bar length, from the basics of measurement to understanding different types and standards.
The Importance of Correct Chainsaw Bar Length
A chainsaw’s bar is the metal strip that guides the chain as it cuts. Its length dictates the maximum cutting capacity of your chainsaw. Using a bar that is too long for your saw can lead to a variety of problems, including:
- Overheating the Engine: A longer bar requires more power to turn the chain. If your chainsaw’s engine isn’t powerful enough, it will struggle, leading to overheating and potential damage.
- Reduced Cutting Efficiency: A bar that is too long can cause the chain to flex and bind, making cuts less efficient and requiring more effort.
- Increased Wear and Tear: The added strain on the engine, clutch, and chain can lead to premature wear on these components.
- Safety Hazards: An improperly matched bar can lead to kickback, a dangerous sudden upward and backward movement of the chainsaw.
Conversely, a bar that is too short might limit your cutting capacity and not be suitable for the tasks you need to perform. Therefore, accurate chainsaw bar length measurement is not just about convenience; it’s about safety and the longevity of your equipment.
Deciphering Chainsaw Bar Dimensions: What Matters?
When you look at a chainsaw bar, several dimensions are important, but for measuring chainsaw bar length, two key figures stand out:
- Pitch: This refers to the distance between the drive links on the chain. It’s typically measured from the center of one rivet to the center of the next rivet. Common pitches include .325”, 3/8”, and .404”.
- Gauge: This is the thickness of the drive links on the chain. It determines how snugly the chain fits into the groove of the bar. Common gauges are .050” and .063”.
- Drive Links: This is the number of metal tabs on the chain that engage with the sprocket and sit inside the bar’s groove. This is the most direct way to determine the bar’s intended length.
While pitch and gauge are critical for chain compatibility, it’s the drive links that directly inform the chainsaw bar size.
How to Measure Chainsaw Bar Length: The Primary Method
The most accurate and universally accepted method for measuring chainsaw bar length is by counting the drive links on the chain that fits the bar.
Step-by-Step Guide to Measuring Drive Links:
- Remove the Chain: Ensure your chainsaw is off and completely cool. Carefully remove the chain from the bar. This usually involves loosening the bar nuts and adjusting the tensioner.
- Lay the Chain Flat: Spread the chain out on a flat surface. Try to untangle any twists or knots.
- Count the Drive Links: A drive link is the part of the chain that has a small tab or “foot” on it. These are the links that sit inside the groove of the chainsaw bar and engage with the drive sprocket. Start at one end and count each individual drive link until you reach the other end.
- Cross-Reference with Manufacturer Specifications: Once you have the drive link count, you can cross-reference this with your chainsaw manufacturer’s specifications or online resources to determine the nominal bar length in inches.
Example:
- A chain with 68 drive links typically corresponds to a 20-inch chainsaw bar.
- A chain with 52 drive links usually fits a 16-inch bar.
Why This Method Works:
Chainsaw manufacturers design their bars to accommodate a specific number of drive links for a given chain pitch and gauge. This standardization ensures that the chain sits correctly within the bar groove, allowing for smooth operation and proper tension.
Alternative Methods for Checking Chainsaw Bar Length
While counting drive links is the most reliable method, there are other ways to ascertain the chainsaw bar length if you’re in a pinch or don’t have the chain readily available.
1. Measuring the Bar Directly (with a Caveat)
You can measure the bar directly with a tape measure, but this method has a crucial nuance.
How to Measure Directly:
- Measure from the Nose to the Powerhead: Place the tape measure at the very tip of the bar’s nose sprocket.
- Measure to the Base Where It Connects to the Saw: Extend the tape measure along the top of the bar to the point where the bar mounts to the chainsaw body (where the bar studs protrude).
- The “Effective” Cutting Length: The number you get from this measurement is the actual length of the bar. However, chainsaw bars are advertised by their cutting length, which is usually about 2 inches shorter than the total bar length. This is because the last 2 inches of the bar are typically covered by the nose sprocket and the mounting area.
Example: A bar that measures 20 inches from the nose to the mounting base will likely be advertised as a 18-inch bar.
The Caveat:
This direct measurement method is less precise for determining what size bar you need to buy because manufacturers list bar lengths based on the cutting length. So, while you can measure the physical bar, you still need to translate that into the commonly understood “advertised” length.
2. Checking Your Chainsaw’s Manual or Stamped Markings
Most chainsaw manuals will clearly state the recommended bar lengths for your specific model.
How to Check Manuals and Markings:
- Consult Your Chainsaw Manual: This is often the easiest and most reliable way to find out the correct chainsaw bar dimensions. Look for sections on specifications or maintenance.
- Look for Stamped Markings on the Bar: Sometimes, the bar itself will have markings indicating its length, pitch, and gauge. These are usually stamped near the base of the bar where it mounts to the saw. Look for numbers like “20” or “18” which represent the advertised cutting length.
Understanding Chainsaw Bar Length Standards and Types
Chainsaw bars come in various lengths and are designed for different types of saws and cutting tasks.
Common Chainsaw Bar Lengths:
Chainsaw bars are typically available in lengths ranging from 10 inches to 36 inches or even longer for specialized professional saws.
- Small Saws (10-14 inches): Ideal for limbing, light pruning, and smaller homeowner tasks.
- Mid-Size Saws (16-20 inches): The most common range for homeowners and general property maintenance. They offer a good balance of cutting power and maneuverability.
- Large Saws (20-24 inches and up): Designed for felling larger trees and more demanding professional work. These require more powerful engines and can be heavier.
Chainsaw Bar Length Types:
While the length is the primary differentiator, bars can also vary in their construction and features.
- Solid Bars: These are made from a single piece of high-quality steel. They are durable and resistant to bending but are also heavier.
- Laminated Bars: These bars are made of three laminations of steel, with the groove for the chain milled into the middle layer. They are lighter than solid bars but can be more prone to bending under heavy stress.
- Roller Nose Bars: These have a replaceable sprocket at the tip of the bar. The roller nose reduces friction, making cutting smoother and more efficient, and can extend the life of the bar and chain.
- Hardnose Bars: These bars have a solid nose with no moving parts. They are generally more durable than roller nose bars but generate more friction.
The chainsaw bar length guide provided by manufacturers will often recommend specific chainsaw bar length types suitable for their engines.
Choosing the Right Bar Length for Your Saw and Task
Selecting the correct chainsaw bar size is a balancing act between your saw’s power, its intended use, and your own comfort and experience.
Matching Bar Length to Saw Power:
- Engine Displacement (cc): Smaller engines (under 40cc) are best suited for shorter bars (10-16 inches). Mid-size engines (40-60cc) can handle 16-20 inch bars effectively. Larger engines (over 60cc) can power longer bars (20 inches and above).
- Horsepower (HP): Similar to cc, higher horsepower engines can drive longer chains with more force.
- Weight of the Saw: A longer bar on a lightweight saw can make the saw unwieldy and difficult to control.
Matching Bar Length to Cutting Task:
- Limbing and Pruning: Shorter bars (10-14 inches) are ideal for these tasks due to their maneuverability and lighter weight.
- Felling Small to Medium Trees: 16-20 inch bars are a popular choice, offering a good balance of reach and power.
- Felling Large Trees: For significantly large trees, longer bars (20 inches and up) are necessary. However, ensure your saw has the power and torque to handle them efficiently and safely.
- General Yard Work: A 16 or 18-inch bar is often sufficient for most homeowner tasks like cutting firewood and clearing brush.
Maintaining Your Chainsaw Bar
Proper maintenance ensures your bar performs optimally and lasts longer.
Key Maintenance Tips:
- Regularly Clean the Bar Groove: Debris, sawdust, and oil can build up in the bar groove. Use a thin screwdriver or a specialized bar cleaner tool to remove this buildup. A clean groove ensures the chain moves smoothly.
- Lubricate the Bar and Chain: Ensure the automatic oiler is working correctly. The oil lubricates the chain and the bar groove, reducing friction and heat. Check the oil reservoir regularly.
- Check for Bar Wear: Over time, the groove in the bar can wear down, becoming wider and shallower. This can lead to the chain derailing. You can check for wear by inserting the tip of a screwdriver into the groove. If it sinks too deeply, the bar may be worn. Many professionals use a bar rail gauge to check for wear.
- Straighten Bent Bars: If your bar gets bent, you might be able to straighten it using specialized tools. However, severely bent bars should be replaced.
- Replace Worn Sprocket Nose: If you have a roller nose bar, the sprocket at the tip will eventually wear out. It’s usually a simple process to replace it, extending the life of your bar.
When to Replace Your Chainsaw Bar:
- Excessive Wear: If the groove is worn out, the chain becomes loose even when properly tensioned.
- Bent or Damaged Bar: Any significant bending or damage to the bar can create safety hazards and affect cutting performance.
- Worn Sprocket Nose: A worn-out sprocket will make your chain jump and reduce cutting efficiency.
Frequently Asked Questions (FAQ)
Here are some common questions regarding chainsaw bar length measurement:
Q1: Can I put a longer bar on my chainsaw than what the manufacturer recommends?
A1: While technically possible, it’s generally not recommended. Using a bar that is too long for your saw can strain the engine, clutch, and chain, leading to overheating, reduced performance, and potential damage or safety hazards like increased kickback risk. Always stick to the recommended bar lengths for your specific chainsaw model.
Q2: How do I know which chain pitch and gauge to use with my bar?
A2: The pitch and gauge are determined by the drive sprocket on your chainsaw and the design of the bar. This information is usually stamped on the bar itself or listed in your chainsaw’s manual. You must use a chain with the correct pitch and gauge that matches your saw and bar. Using the wrong pitch or gauge can damage the saw and the chain.
Q3: Does the number of teeth on the nose sprocket affect the bar length?
A3: The number of teeth on the nose sprocket (if it’s a roller nose bar) affects the chain’s speed and efficiency but not the physical length of the bar itself. Bar length is primarily determined by the number of drive links.
Q4: What does “effective cutting length” mean for a chainsaw bar?
A4: The effective cutting length is the primary measurement used when referring to a chainsaw bar’s size (e.g., 16 inches, 20 inches). It’s the length of the bar that is actually in contact with the wood during a cut, excluding the nose sprocket and the mounting area.
Q5: How do I check my chainsaw bar for wear?
A5: You can check for wear by looking at the groove in the bar. If the groove looks wide and shallow, or if a flathead screwdriver can sink deeply into it, the bar is likely worn. You can also use a specialized bar gauge tool for a more precise measurement. A worn bar should be replaced to ensure safe and efficient operation.
By following this comprehensive guide, you’ll be well-equipped to accurately measure your chainsaw bar length, choose the correct replacement, and ensure your equipment performs at its best for years to come. Remember, safety and proper fit are paramount when working with chainsaws.