Stihl MS251 Chain Size Guide (5 Pro Tips for Perfect Filing)
I remember the first time I tried to sharpen a chainsaw chain. I thought, “How hard could it be?” Famous last words, right? I ended up with a chain that cut slower than a butter knife through cold concrete. It was a frustrating experience, especially when I was trying to get a winter’s worth of firewood stacked before the first snow. That’s why I’m writing this guide – to help you avoid the same pitfalls I stumbled into and to ensure your Stihl MS251 chainsaw is always ready to rip.
The global wood processing and firewood industry is a significant one. Did you know that the global firewood market was valued at approximately USD 26.9 billion in 2023 and is projected to reach USD 34.5 billion by 2033, according to a recent market research report? This highlights the continued importance of efficient and effective wood processing, whether for heating, cooking, or other applications. In the US alone, over 70 million cords of firewood are burned annually. And while modern heating systems are prevalent, the charm and reliability of a wood-burning stove or fireplace remain strong, driving demand for quality firewood. Properly maintaining your chainsaw is crucial to meeting that demand, whether you’re a hobbyist or a professional.
Stihl MS251 Chain Size Guide (5 Pro Tips for Perfect Filing)
The Stihl MS251 is a popular chainsaw, known for its versatility and reliability. It’s a fantastic choice for homeowners, farmers, and even some professionals tackling smaller jobs. But like any chainsaw, its performance hinges on having the right chain and keeping it properly sharpened. This guide will walk you through everything you need to know about Stihl MS251 chain sizes, how to choose the right one, and, most importantly, how to file it like a pro.
Understanding Stihl MS251 Chain Specifications
Before we dive into filing techniques, let’s nail down the basics of chain specifications. This will help you choose the right chain and understand the numbers stamped on your guide bar and chain.
- Pitch: The pitch is the distance between any three consecutive rivets divided by two. It’s measured in inches. The Stihl MS251 typically uses a 3/8″ low profile (also known as .375″) pitch chain.
- Gauge: The gauge is the thickness of the drive links that fit into the groove of the guide bar. It’s also measured in inches. The MS251 usually requires a .050″ gauge chain.
- Drive Links: The number of drive links is the number of links that fit into the guide bar. This is crucial for matching the chain to your specific guide bar length. The MS251 commonly uses guide bars ranging from 16″ to 18″, which translates to roughly 55 to 61 drive links, respectively. Always double-check the specifications for your particular bar.
Why are these specifications important? Using the wrong pitch or gauge chain can damage your chainsaw and be extremely dangerous. Too few drive links, and the chain won’t fit. Too many, and you’ll have slack that can cause the chain to derail.
Choosing the Right Chain for Your Needs
The Stihl MS251 is a versatile chainsaw, and you have several chain options. Here’s a breakdown to help you decide:
- Stihl RSC (Rapid Super Comfort): This is a popular semi-chisel chain known for its all-around performance. It’s a good choice for general firewood cutting and felling smaller trees. It holds an edge well and is relatively easy to file.
- Stihl RM (Rapid Micro): This is a full-chisel chain designed for faster cutting in clean wood. It requires more frequent filing but offers superior performance when sharp. It’s ideal if you’re primarily cutting seasoned hardwood.
- Stihl RMC (Rapid Micro Comfort): A low-kickback chain designed for safety. Good for beginners and those who prioritize safety over maximum cutting speed.
My Recommendation: For most users of the Stihl MS251, the RSC (Rapid Super Comfort) chain offers the best balance of performance, durability, and ease of maintenance.
Pro Tip #1: Understanding Chain Anatomy – The Key to Effective Filing
Before you start grinding away at your chain, let’s take a closer look at its anatomy. Knowing the parts of the cutter will make filing much easier.
- Cutter: This is the part of the chain that actually does the cutting. It has a top plate, a side plate, and a depth gauge.
- Depth Gauge (Raker): This controls the amount of wood the cutter takes with each pass. Think of it like a tiny plane blade.
- Tie Straps: These connect the cutters and drive links.
- Drive Links: These fit into the guide bar and pull the chain around.
Why is this important? Filing the cutter correctly is only half the battle. You also need to maintain the correct depth gauge height. If the depth gauge is too high, the cutter won’t bite into the wood. If it’s too low, the chain will grab aggressively and be prone to kickback.
Pro Tip #2: Gathering Your Sharpening Tools – Setting Yourself Up for Success
Having the right tools is essential for achieving a professional-quality chain sharpening. Here’s what you’ll need:
- Chainsaw File: Use the correct diameter file for your chain’s pitch. For a 3/8″ low profile chain, a 5/32″ (4.0mm) file is usually required. Stihl also offers file kits with the file holder, depth gauge tool, and the correct size files.
- File Holder (Filing Guide): This helps you maintain the correct filing angle and depth. It’s a worthwhile investment, especially for beginners.
- Depth Gauge Tool (Raker Gauge): This is used to check and adjust the height of the depth gauges.
- Flat File: For filing the depth gauges.
- Vise or Chainsaw Filing Clamp: To hold the chainsaw securely while you’re filing. A stump vise is a great option if you’re working in the field.
- Gloves: To protect your hands.
- Eye Protection: Always wear eye protection when filing.
- Cleaning Brush: To remove filings from the chain.
Cost Breakdown: A basic chainsaw file kit can cost around $20-$40. A good quality vise or filing clamp can range from $30-$70.
My Experience: I initially tried filing freehand, but my results were inconsistent. Investing in a file holder made a huge difference in the sharpness and consistency of my chain.
Pro Tip #3: The Step-by-Step Filing Process – Transforming Dull to Razor Sharp
Now, let’s get down to the nitty-gritty of filing. Follow these steps carefully for optimal results:
- Secure the Chainsaw: Clamp the chainsaw securely in a vise or use a chainsaw filing clamp. Make sure the chain is free to rotate.
- Identify the Sharpest Cutter: Before you start filing, find the sharpest cutter on the chain. This will serve as your reference for filing the rest of the cutters.
- Position the File: Place the file in the file holder, ensuring the arrow on the holder points in the direction of the chain’s rotation.
- File at the Correct Angle: The file holder will help you maintain the correct filing angle. Typically, this is around 30 degrees relative to the guide bar and 10 degrees down from horizontal. Check your file holder’s instructions for the exact angles.
- File Each Cutter: Using smooth, even strokes, file each cutter from the inside out. Apply light pressure on the forward stroke and release on the return stroke. Count the number of strokes required to sharpen the reference cutter and use the same number of strokes for all other cutters.
- Maintain Consistency: As you file, pay close attention to the length and shape of the cutter. Try to maintain a consistent shape and length for all cutters on the chain.
- Check Your Work: After filing a few cutters, step back and examine your work. Are you maintaining the correct angles? Are the cutters all the same length and shape?
- File All Cutters: Rotate the chain and repeat the filing process for all cutters on the chain.
- File the Depth Gauges: After filing the cutters, use the depth gauge tool to check the height of the depth gauges. If they are too high, use a flat file to lower them. File them evenly, maintaining a slightly rounded profile. Consult your chainsaw manual for the recommended depth gauge setting. This setting often depends on the type of wood you’re cutting – softer wood requires a lower depth gauge.
- Clean the Chain: Use a cleaning brush to remove any filings from the chain.
- Lubricate the Chain: Apply chain oil to the chain before using it.
Important Note: It’s better to file frequently with a few light strokes than to wait until the chain is extremely dull and then try to sharpen it with many heavy strokes.
Pro Tip #4: Mastering Depth Gauge Adjustment – Fine-Tuning for Optimal Performance
Adjusting the depth gauges (rakers) is often overlooked, but it’s crucial for achieving optimal cutting performance. The depth gauge controls how much wood the cutter takes with each pass.
- Checking the Depth Gauge Height: Use a depth gauge tool to check the height of the depth gauges relative to the cutters. Place the tool on the chain, and if the depth gauge protrudes above the tool, it needs to be filed down.
- Filing the Depth Gauges: Use a flat file to file down the depth gauges. File them evenly, maintaining a slightly rounded profile.
- Recommended Depth Gauge Settings: Consult your chainsaw manual for the recommended depth gauge setting. As a general guideline, a setting of .025″ to .030″ is a good starting point for most applications. Softer woods may benefit from a slightly lower setting.
The Consequences of Incorrect Depth Gauge Settings:
- Depth Gauges Too High: The chain will cut slowly and may bounce or chatter.
- Depth Gauges Too Low: The chain will grab aggressively and be prone to kickback. It can also overload the engine.
Pro Tip #5: Avoiding Common Filing Mistakes – Learning from My Blunders
Over the years, I’ve made my fair share of mistakes when filing chainsaw chains. Here are some common pitfalls to avoid:
- Using the Wrong Size File: Using a file that’s too large or too small will result in an improperly shaped cutter.
- Filing at the Wrong Angle: Maintaining the correct filing angle is crucial for achieving a sharp and efficient cutting edge. Use a file holder to ensure consistent angles.
- Filing Unevenly: Filing some cutters more than others will result in a chain that cuts unevenly.
- Ignoring the Depth Gauges: Neglecting to check and adjust the depth gauges will significantly reduce the chain’s cutting performance.
- Over-Filing: Removing too much material from the cutters will shorten the life of the chain.
- Dulling the File: Using a dull file will make the filing process more difficult and less effective. Replace your files regularly.
- Not Securing the Chainsaw: Trying to file a chainsaw that isn’t properly secured is dangerous and will result in inconsistent filing.
- Not Wearing Eye Protection: Metal filings can easily fly into your eyes, causing serious injury. Always wear eye protection when filing.
My Biggest Mistake: I once tried to sharpen a chain with a file that was completely worn out. I spent hours filing, but the chain never got sharp. I learned the hard way that a sharp file is essential for effective sharpening.
Troubleshooting Common Chainsaw Problems
Even with a perfectly sharpened chain, you might encounter some common chainsaw problems. Here’s a quick troubleshooting guide:
- Chain Won’t Cut:
- Check the chain tension. A loose chain will not cut effectively.
- Make sure the chain is installed correctly.
- Check the depth gauge settings.
- The chain may be dull and need filing.
- Chain Smokes:
- Check the chain oil level. A lack of lubrication will cause the chain to overheat and smoke.
- Make sure the oiler is working properly.
- The chain may be too tight.
- Chain Kicks Back:
- Use a low-kickback chain.
- Maintain a firm grip on the chainsaw.
- Avoid cutting with the tip of the bar.
- Ensure the depth gauges are not too low.
- Chainsaw Won’t Start:
- Check the fuel level.
- Make sure the spark plug is clean and in good condition.
- Check the air filter.
- The carburetor may need to be cleaned or adjusted.
Firewood Preparation: From Tree to Hearth
Sharpening your chainsaw is just one piece of the firewood preparation puzzle. Here’s a brief overview of the entire process:
- Felling the Tree: This is the most dangerous part of the process. If you’re not experienced, consider hiring a professional.
- De-limbing: Remove the branches from the felled tree.
- Bucking: Cut the tree into manageable lengths (usually 16-18 inches for firewood).
- Splitting: Split the logs into smaller pieces for faster drying. Use a maul, splitting axe, or log splitter.
- Stacking: Stack the firewood in a well-ventilated area to allow it to dry properly.
- Seasoning: Allow the firewood to season for at least six months, preferably longer. The ideal moisture content for firewood is below 20%.
Data Point: Studies have shown that properly seasoned firewood burns more efficiently, produces more heat, and creates less smoke than green wood. Green wood can have a moisture content of over 50%, while seasoned wood should be below 20%.
My Firewood Stacking Strategy: I stack my firewood in long rows, with spaces between the rows to allow for air circulation. I also cover the top of the stack with a tarp to protect it from rain and snow, but I leave the sides open to allow for ventilation.
Budgeting for Firewood Preparation
Preparing firewood can be a cost-effective way to heat your home, but it’s important to factor in all the costs involved. Here’s a breakdown of potential expenses:
- Chainsaw: $200 – $500 (or more for professional models)
- Chainsaw Maintenance: $50 – $100 per year (for files, oil, spark plugs, etc.)
- Splitting Axe or Maul: $50 – $100
- Log Splitter (Optional): $500 – $2000
- Safety Gear: $50 – $100 (helmet, eye protection, gloves, chaps)
- Fuel and Oil: $20 – $50 per month (depending on usage)
- Transportation: Varies depending on the distance to the wood source.
Cost-Saving Tip: Consider purchasing used equipment or borrowing tools from friends or neighbors. You can also save money by gathering firewood from your own property or obtaining a permit to harvest firewood from public lands.
Next Steps and Additional Resources
Now that you have a better understanding of Stihl MS251 chain sizes and how to file them, it’s time to put your knowledge into practice. Here are some additional resources to help you on your wood processing journey:
- Stihl Website: For information on Stihl chainsaws and accessories.
- Local Chainsaw Dealers: For expert advice and service.
- Forestry Associations: For information on sustainable forestry practices and firewood harvesting permits.
- Online Forums and Communities: Connect with other chainsaw enthusiasts and share tips and experiences.
Suppliers of Logging Tools and Drying Equipment:
- Northern Tool + Equipment: Offers a wide range of logging tools, log splitters, and firewood processing equipment.
- Bailey’s: Specializes in forestry and logging supplies.
- Amazon: Carries a variety of chainsaw files, file holders, and other sharpening tools.
By following the tips and techniques outlined in this guide, you can keep your Stihl MS251 chainsaw running smoothly and efficiently for years to come. Remember to always prioritize safety and take your time. With a little practice, you’ll be filing your chainsaw chains like a pro in no time. Happy cutting!
