What is the correct way to measure a chainsaw bar? Measuring a chainsaw bar correctly involves measuring the length from the tip of the bar to the point where it meets the chainsaw body, and also counting the number of drive links on the chain. This guide will break down the process step-by-step.
When you own a chainsaw, knowing how to properly maintain it is key to its longevity and your safety. One of the most important components to understand is the chainsaw bar. Whether you need to replace a worn-out bar, order a new chain, or simply want to know your chainsaw’s capabilities, accurate chainsaw bar measurement is essential. This comprehensive guide will walk you through everything you need to know about measuring your chainsaw bar, ensuring you get the right parts and keep your saw running smoothly.
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Why Accurate Chainsaw Bar Measurement Matters
Getting the chainsaw bar length right is not just about aesthetics; it’s about performance and safety. Using a bar that’s too long or too short can lead to a variety of problems:
- Reduced Performance: A bar that’s too long for your chainsaw’s engine can overwork the motor, leading to overheating and reduced cutting efficiency. Conversely, a bar that’s too short might not be able to handle the tasks you need it for.
- Chain Fit Issues: The chain needs to perfectly match the bar’s groove and the sprocket. An incorrect bar size can mean a chain won’t fit, or worse, it might fit loosely and derail, causing damage or injury.
- Safety Hazards: An improperly fitted bar or chain can be unstable during operation. This increases the risk of kickback, a sudden and violent upward and backward motion of the chainsaw that can cause serious injury.
- Damage to Your Chainsaw: Using the wrong bar can put undue stress on your chainsaw’s clutch, engine, and other components, leading to premature wear and expensive repairs.
The Key Measurements: Length and Drive Links
When we talk about measuring a chainsaw bar, there are two primary aspects to consider: the physical length of the bar itself and the number of drive links on the corresponding chain.
1. Measuring the Chainsaw Bar Length
The most common way to measure your chainsaw bar is to determine its effective cutting length.
How to Measure Chainsaw Bar Length: A Step-by-Step Approach
- Safety First: Always ensure your chainsaw is turned off and the chain brake is engaged before you begin any measurements or maintenance.
- Locate the Mounting Point: Identify where the chainsaw bar attaches to the chainsaw’s powerhead. This is usually at the base of the bar.
- Measure to the Tip: Using a tape measure or ruler, measure the length from the very tip of the bar (the nose sprocket, if it has one) down to the point where the bar meets the chainsaw body.
- Exclude the Mount: Do not include the portion of the bar that slots into the chainsaw’s powerhead in your measurement. This is a common mistake. You are measuring the portion that is exposed and does the cutting.
- Record the Measurement: It’s typically best to measure in inches. For example, a common chainsaw bar length might be 16 inches, 18 inches, or 20 inches.
Important Note: While the direct measurement from the tip to the mount is a good indicator, the actual cutting length is what matters most for chain compatibility. This is often slightly less than the measured length due to the way the chain wraps around the bar’s nose sprocket. However, for ordering purposes, the measured length is usually sufficient, and manufacturers provide chainsaw bar length charts that correlate these measurements with specific chain sizes.
Interpreting Chainsaw Bar Lengths
Chainsaw bars come in various lengths, and each is designed for a specific range of chainsaw models and cutting tasks.
- Smaller Bars (10-14 inches): Ideal for light-duty tasks like pruning, limbing, and felling small trees. They offer excellent maneuverability.
- Medium Bars (16-20 inches): Versatile and suitable for a wide range of applications, from cutting firewood to felling medium-sized trees. This is a very common chainsaw guide bar measurement for many homeowner and professional saws.
- Larger Bars (22 inches and above): Designed for demanding jobs like felling large trees and cutting thick logs. These require more powerful chainsaws.
2. Counting the Drive Links on the Chain
The number of drive links on your chainsaw chain is just as crucial as the bar length for ensuring a proper fit. The drive links are the bottom portions of the chain that sit within the groove of the chainsaw bar and engage with the drive sprocket.
How to Measure a Chainsaw Chain: Counting Drive Links
- Disengage the Chain: Ensure the chainsaw is off and the chain is safely removed from the bar if you are doing a full replacement. If measuring on the saw, ensure the chain brake is engaged and the saw is off.
- Identify a Drive Link: Look at the chain. You’ll see alternating cutters and drive links. The drive links are the ones with the small tabs on the bottom that fit into the bar groove.
- Count Carefully: Start with any drive link and count each subsequent drive link all the way around the chain until you return to your starting point.
- Double-Check: It’s easy to miscount. Run through the count a second time to confirm the total number.
- Record the Number: Make a note of the total number of drive links. This is a critical piece of chainsaw parts measurement.
Why is this important? The number of drive links dictates the circumference of the chain. If you have the wrong number of drive links for your bar, the chain will either be too loose (and likely come off) or too tight (and bind or break), causing damage.
Beyond Basic Measurement: Gauging Bar Compatibility
While measuring the length and counting drive links are the primary steps, several other factors contribute to proper bar and chain compatibility. This is where understanding chainsaw bar identification and chainsaw parts measurement becomes vital.
Gauge: The Thickness of the Drive Link
The gauge refers to the thickness of the drive links on your chainsaw chain. This thickness must match the groove in the chainsaw bar.
- Common Gauges: The most common chainsaw chain gauges are:
- .050 inches (or 1.3mm)
- .058 inches (or 1.5mm)
- .063 inches (or 1.6mm)
How to Determine Chain Gauge
- Check the Bar: Most chainsaw bars have the gauge stamped on them, usually near the mounting end. Look for numbers like “.050”, “1.3”, “.058”, “1.5”, “.063”, or “1.6”.
- Check the Old Chain: If the old chain fits correctly, you can measure the thickness of one of its drive links with calipers.
- Consult Your Chainsaw Manual: Your owner’s manual will specify the correct gauge for your saw.
- Professional Advice: If you’re unsure, take your old chain or bar to a reputable power equipment dealer.
Pitch: The Spacing Between Drive Links
The pitch is the distance between drive links, measured from the center of one drive link to the center of the next. This measurement is critical for the chain to mesh properly with the drive sprocket and the bar’s nose sprocket.
- Common Pitches:
- 3/8 inch (often referred to as 3/8″)
- .325 inch (often referred to as .325)
- 1/4 inch (often referred to as 1/4)
- .404 inch (less common for homeowner saws)
How to Determine Chain Pitch
- Check the Bar: Like the gauge, the pitch is usually stamped on the chainsaw bar. It might be written as “3/8”, “.325”, or “1/4”.
- Check the Old Chain: You can measure the pitch of an old chain. A common method is to measure the distance across three consecutive drive links and divide by two. For example, if the distance is 1.5 inches, the pitch is 0.5 inches (or 3/8 inch).
- Consult Your Chainsaw Manual: Your manual will specify the correct pitch.
Groove Width: The Slot in the Bar
The groove width is the width of the channel in the chainsaw bar where the drive links sit. This must match the gauge of your chain. For example, if you have a .050 gauge chain, you need a bar with a .050 groove width. This is a crucial aspect of chainsaw guide bar specifications.
Chainsaw Bar Identification and Model Numbers
Many manufacturers use specific chainsaw bar model number systems or provide a chainsaw bar identification system that helps users quickly determine compatibility.
Where to Find Model Numbers and Identification
- On the Bar Itself: Look for stamped or etched information on the bar, usually near the base where it mounts to the chainsaw. This often includes the manufacturer’s name, the bar length, pitch, gauge, and sometimes a specific part number.
- On Your Chainsaw: The chainsaw bar type is often indicated on a sticker or plate on the chainsaw body itself, or in the owner’s manual. This will tell you the recommended bar length, pitch, and gauge.
- On the Original Packaging: If you still have the packaging for your chainsaw or a previous replacement bar, it will contain all the necessary information.
Using Manufacturer-Specific Information
Different chainsaw brands (e.g., Stihl, Oregon, Husqvarna) have their own naming conventions and part numbers for bars. Knowing your chainsaw’s brand and model number is the first step to finding the correct replacement bar. For instance, a Stihl 3627 000 0064 bar might be for a specific Stihl saw and have a defined length, pitch, and gauge.
Example: A common Oregon bar might be listed as “200GXGK095”.
* “200” often indicates the length (20 inches).
* “GX” might indicate a particular series or type of mount.
* “GK” could refer to the pitch and gauge.
* “095” might be a specific model identifier.
It’s always best to cross-reference this information with your chainsaw’s manual or reliable online parts finders.
Special Chainsaw Bar Types
Beyond the standard guide bars, there are specialized types that might affect how you measure or what you need:
- Roller Nose Bars: These have a sprocket at the tip to reduce friction and wear. The measurement method remains the same, but the nose sprocket adds a slight complexity to visual inspection, though your tape measure will still go to the very end.
- Hardnose Bars: These have a solid nose without a sprocket. They are generally less expensive but can cause more friction and wear. Measurement is straightforward.
- Carving Bars: These are typically shorter and have a very narrow tip, designed for detailed carving work. While the measurement principle is the same, their specialized shape means you need to be very precise.
Tools You’ll Need for Accurate Measurement
Having the right tools ensures the precision needed for correct chainsaw parts measurement:
- Tape Measure: A standard metal tape measure is usually sufficient for measuring the bar length.
- Ruler: For smaller chainsaws or more intricate measurements.
- Calipers (Optional but Recommended): Digital or dial calipers are ideal for accurately measuring the chain gauge and bar groove width.
- Magnifying Glass (Optional): Helpful for reading small stamped numbers on bars.
- Chainsaw Owner’s Manual: Your definitive source for specifications.
- Pen and Paper: To record your measurements.
When to Replace Your Chainsaw Bar
Even with correct measurement, chainsaw bars wear out. Here are signs that it’s time for a replacement:
- Worn Groove: The groove where the chain sits becomes wider than specified, causing the chain to wobble or run loose.
- Burring: Metal shavings build up along the edges of the bar groove, particularly at the nose.
- Warping: The bar can become bent or twisted from use, impacting cutting accuracy and safety.
- Damaged Nose Sprocket: If the roller nose sprocket is stiff, doesn’t spin freely, or is visibly worn, it needs replacement.
- Excessive Wear: The overall length of the bar can effectively shorten as the rails wear down.
Using a Chainsaw Bar Length Chart and Online Resources
Once you have your measurements, you might need to consult a chainsaw bar length chart or use online resources to find the correct replacement.
- Manufacturer Websites: Most major chainsaw and bar manufacturers have online tools where you can input your chainsaw model number to find compatible bars and chains.
- Online Retailers: Many online stores that sell chainsaw parts have detailed product descriptions and compatibility guides.
- Specialty Forums and Communities: Chainsaw enthusiasts often share information and can help identify parts.
Putting It All Together: Ensuring Compatibility
Let’s say you’ve measured your bar to be 18 inches, counted 66 drive links on your chain, and found the pitch stamped on the bar is .325, with a gauge of .050.
When purchasing a new bar or chain, you would look for:
- Bar: An 18-inch bar with a .325 pitch and .050 gauge.
- Chain: A chain for an 18-inch bar, with .325 pitch, .050 gauge, and specifically 66 drive links.
These chainsaw guide bar specifications must align perfectly.
Frequently Asked Questions (FAQ)
Q1: Can I put a longer or shorter bar on my chainsaw?
A: While technically possible, it is generally not recommended. Using a bar length different from what the manufacturer specifies can strain your engine, affect lubrication, and increase the risk of kickback. Always stick to the recommended chainsaw bar length for your saw’s model.
Q2: How do I know if my chainsaw bar is worn out?
A: Look for a widened groove, burrs along the edges, a bent or twisted bar, or a damaged nose sprocket. If the chain sits loosely in the groove, it’s time for a new bar.
Q3: What is the difference between pitch and gauge?
A: Pitch refers to the spacing between drive links (e.g., .325 inches), and gauge refers to the thickness of the drive link (e.g., .050 inches). Both are critical for proper chain and bar fit.
Q4: My bar has a number like ’20-50-325′. What does that mean?
A: This is a common shorthand for chainsaw bar identification. It typically means:
* 20: Bar length in inches.
* 50: Chain gauge (e.g., .050 inches).
* 325: Chain pitch (e.g., .325 inches).
Q5: Do I need to measure my bar every time I buy a new chain?
A: Ideally, yes, or at least know the exact specifications (length, pitch, gauge) for your saw. Even if you think you remember, it’s best to confirm to avoid errors. Remembering the number of drive links is also essential for ordering the correct chain.
By following this guide, you’ll be well-equipped to accurately measure your chainsaw bar and chain, ensuring you select the correct parts for optimal performance, safety, and the longevity of your chainsaw. Happy cutting!