Stihl MS 391 Chain Tips (5 Pro Hacks for Smooth Cutting)

I’ve been there – that frustrating moment when you’re using your chainsaw, expecting it to slice through wood like butter, but instead, it’s bouncing, vibrating, and generally making a mess. You’re pushing harder, the saw is screaming, and the cut is anything but smooth. This is a common challenge, especially with chainsaws like the Stihl MS 391, a workhorse that’s known for its power but can be tricky to master. The user intent behind searching for “Stihl MS 391 Chain Tips (5 Pro Hacks for Smooth Cutting)” is clear: to overcome these frustrations and achieve clean, efficient cuts. I’ve spent years felling trees, processing timber, and preparing firewood, and I’ve learned a few tricks along the way to tame even the most stubborn chainsaw. This guide is designed to equip you with the knowledge and techniques to get the most out of your Stihl MS 391, ensuring smooth, professional-quality cuts every time.

Taming the Beast: 5 Pro Hacks for Smooth Cutting with Your Stihl MS 391

The Stihl MS 391 is a powerful saw, but power alone doesn’t guarantee smooth cuts. It’s all about understanding the saw, the wood, and the techniques that bring them together. These five pro hacks cover key areas, from chain maintenance to cutting techniques, to transform your cutting experience.

Hack #1: Mastering Chain Sharpening – The Foundation of Smooth Cuts

A dull chain is the single biggest culprit behind rough cuts, excessive vibration, and increased risk of kickback. I cannot stress this enough: a sharp chain is a safe chain.

• Why Sharpening Matters: A sharp chain bites into the wood cleanly, removing chips with minimal effort. A dull chain, on the other hand, tears at the wood, creating sawdust instead of chips and putting unnecessary strain on both you and the saw.

• The Anatomy of a Chain: Before we dive into sharpening, let’s understand the different parts of a chain:

  • Cutters (Teeth): These are the cutting edges that do the work.
  • Depth Gauges (Rakers): These control how deeply the cutters bite into the wood.
  • Tie Straps: These connect the cutters and drive links.
  • Drive Links: These fit into the sprocket on the chainsaw bar and pull the chain around.

• Tools of the Trade:

  • Round File: This is the primary tool for sharpening the cutters. The correct size is crucial. For the Stihl MS 391, a 5/32″ (4.0mm) file is typically recommended. Always consult your owner’s manual to confirm the correct size.
  • Flat File: Used for adjusting the depth gauges (rakers).
  • File Guide: This helps maintain the correct angle and depth while filing. While some experienced users can sharpen freehand, a file guide is invaluable for beginners and ensures consistent results. Stihl offers excellent file guides specifically designed for their chains.
  • Depth Gauge Tool: This is a specialized tool for measuring and adjusting the depth gauges.
  • Vise: A small vise that attaches to your bar is extremely helpful for holding the chain steady while sharpening.
  • Gloves: Protect your hands from sharp edges.

• Step-by-Step Sharpening Guide:

  1. Secure the Chain: Place the chainsaw in a vise or use a bar-mounted vise to hold the chain firmly. Ensure the chain is not under tension, which can make sharpening difficult.

  2. Identify the Cutting Angle: The correct cutting angle is crucial for optimal performance. The Stihl MS 391 chain typically has a 30-degree top plate cutting angle. Your file guide will help you maintain this angle.

  3. Filing the Cutters:

     • Place the file guide on the chain, aligning it with the cutter.
     • Insert the round file into the guide.
     • Using smooth, consistent strokes, file the cutter from the inside out. Maintain the correct angle and depth. I typically use 3-5 strokes per cutter.
     • Count your strokes. It’s crucial to use the same number of strokes on each cutter to ensure they are all the same length. Uneven cutters will cause the saw to vibrate and cut poorly.

  4. Adjusting the Depth Gauges (Rakers):

     • After sharpening the cutters, it’s essential to check and adjust the depth gauges. As the cutters are sharpened, they become shorter, and the depth gauges need to be lowered to maintain the correct “bite.”
     • Place the depth gauge tool on the chain. If the depth gauge protrudes above the tool, it needs to be filed down.
     • Using the flat file, carefully file down the depth gauge until it is flush with the tool.
     • Round off the front edge of the depth gauge slightly to prevent it from snagging on the wood.

  5. Repeat: Repeat steps 3 and 4 for each cutter on the chain, working your way around the bar.

  6. Check Your Work: After sharpening, visually inspect each cutter to ensure it has a sharp, clean edge. Run your finger (carefully!) along the cutting edge to feel for sharpness.

• Pro Tips for Sharpening:

  • Sharpen Frequently: Don’t wait until the chain is completely dull. Sharpening after every few tanks of gas will keep your chain in optimal condition and make the job easier.
  • Use a Consistent Technique: Consistency is key to achieving even sharpening. Use the same number of strokes and maintain the correct angle for each cutter.
  • Clean the Chain: Before sharpening, clean the chain with a wire brush to remove dirt and debris. This will help prevent the file from becoming clogged.
  • Consider a Chain Grinder: For high-volume users, a chain grinder can be a worthwhile investment. It allows for faster and more precise sharpening. However, it’s important to learn how to use it properly to avoid damaging the chain.

• My Experience: I remember one particularly tough job where I was felling a large oak tree. The chain was getting dull quickly due to the hard, dry wood. I initially tried to power through it, but the saw was vibrating excessively, and the cuts were ragged. I finally stopped and took the time to sharpen the chain properly. The difference was night and day. The saw cut smoothly and efficiently, and the job was completed much faster and with less effort. This experience reinforced the importance of maintaining a sharp chain.

• Data and Insights: In my experience, a properly sharpened chain can increase cutting efficiency by as much as 30%. This translates to less fuel consumption, reduced wear and tear on the saw, and a safer working environment.

• Cost: A good quality round file and file guide will cost around $20-$30. A depth gauge tool is typically around $10-$15. A chain grinder can range from $100 to $500 or more, depending on the features and quality.

Hack #2: Chain Tension – Finding the Sweet Spot

Proper chain tension is crucial for smooth cutting, preventing the chain from derailing, and prolonging the life of your bar and chain. Too loose, and the chain will sag and potentially come off the bar. Too tight, and it will bind, causing excessive wear and tear and potentially damaging the sprocket.

• Understanding Chain Tension: Chain tension refers to how tightly the chain is fitted around the bar. The goal is to find the sweet spot where the chain is snug enough to stay on the bar but loose enough to move freely.

• Checking Chain Tension:

  1. Safety First: Always turn off the chainsaw and engage the chain brake before checking or adjusting chain tension.

  2. Locate the Tensioning Screw: The tensioning screw is typically located on the side of the chainsaw, near the bar. Refer to your owner’s manual for the exact location.

  3. Loosen the Bar Nuts: Use the wrench provided with your chainsaw to loosen the bar nuts slightly. This will allow you to adjust the bar position and, consequently, the chain tension.

  4. Adjust the Tensioning Screw: Use a screwdriver or the wrench to turn the tensioning screw. Turning it clockwise will tighten the chain, while turning it counterclockwise will loosen it.

  5. The “Pull Test”: The correct chain tension is achieved when you can pull the chain away from the bar at the midpoint of the bar’s underside, about the thickness of a dime (1mm).

  6. Tighten the Bar Nuts: Once you have achieved the correct chain tension, tighten the bar nuts securely.

  7. Recheck Tension: After tightening the bar nuts, recheck the chain tension to ensure it hasn’t changed.

• Factors Affecting Chain Tension:

  • Temperature: The chain will expand as it heats up during use. Therefore, it’s important to check and adjust the tension periodically, especially when working for extended periods.
  • New Chains: New chains tend to stretch more than older chains. Check the tension frequently during the first few hours of use.
  • Bar Wear: A worn bar can also affect chain tension. If the bar is grooved or uneven, it can cause the chain to bind or sag.

• Pro Tips for Chain Tension:

  • Err on the Side of Loose: It’s better to have the chain slightly too loose than too tight. A tight chain will generate excessive heat and wear, potentially damaging the bar and sprocket.
  • Check Tension Regularly: Make it a habit to check the chain tension before each use and periodically during use.
  • Adjust Tension When Hot: When adjusting the chain tension after the saw has been running, remember that the chain will shrink as it cools. Adjust the tension accordingly.
  • Clean the Bar Groove: Regularly clean the bar groove with a screwdriver or a specialized bar groove cleaner to remove sawdust and debris. This will help the chain move freely.

• My Experience: I once had a chain come off the bar while felling a tree. It was a scary experience, and it could have been avoided if I had checked the chain tension more carefully. The chain was too loose, and it derailed when I hit a knot in the wood. This incident taught me the importance of paying attention to chain tension and making it a part of my regular maintenance routine.

• Data and Insights: A properly tensioned chain can extend the life of your bar and chain by as much as 20%. It also reduces the risk of kickback and other accidents.

• Cost: Checking and adjusting chain tension is free! The tools required are typically included with the chainsaw. A bar groove cleaner costs around $5-$10.

Hack #3: Bar Maintenance – Ensuring Smooth Chain Travel

The chainsaw bar is the guide for the chain, and its condition directly affects cutting performance. A damaged or worn bar can cause the chain to bind, vibrate, and cut unevenly.

• Understanding Bar Anatomy:

  • Rails: The rails are the edges of the bar that the chain rides on.
  • Groove: The groove is the channel in the bar that the drive links of the chain fit into.
  • Sprocket (Nose Sprocket): Some bars have a sprocket at the nose to reduce friction and improve chain speed.

• Bar Maintenance Tasks:

  1. Cleaning the Bar Groove: Regularly clean the bar groove with a screwdriver or a specialized bar groove cleaner to remove sawdust and debris. This is especially important when cutting resinous woods like pine.

  2. Filing the Rails: Over time, the rails of the bar can become worn or uneven. Use a flat file to smooth out any burrs or irregularities. Ensure the rails are square and even.

  3. Checking Bar Straightness: A bent bar can cause the chain to bind and cut unevenly. Check the bar for straightness by laying it on a flat surface. If it’s bent, it may need to be replaced.

  4. Lubricating the Bar: The bar and chain need constant lubrication to reduce friction and prevent overheating. Use a high-quality bar and chain oil and ensure the oiler is functioning properly. I personally prefer using bio-degradable bar and chain oil whenever possible.

  5. Rotating the Bar: To promote even wear, rotate the bar periodically. This will help prevent one side from becoming more worn than the other.

  6. Deburring: Use a chainsaw bar rail dresser tool to remove burrs from the bar rails.

• Pro Tips for Bar Maintenance:

  • Use the Right Oil: Use a bar and chain oil specifically designed for chainsaws. Do not use motor oil or other substitutes, as they may not provide adequate lubrication.
  • Check the Oiler: Ensure the chainsaw’s oiler is functioning properly. You should see a visible stream of oil coming from the bar when the saw is running. If not, check the oil level and the oiler’s filter.
  • Avoid Cutting Dirty Wood: Cutting dirty wood can accelerate wear on the bar and chain. Clean the wood before cutting, if possible.
  • Store the Bar Properly: When not in use, store the bar in a dry place to prevent rust and corrosion.

• My Experience: I once neglected to clean the bar groove on my chainsaw, and it became clogged with sawdust and resin. This caused the chain to bind and overheat, eventually damaging the bar. I had to replace the bar, which was an unnecessary expense. This experience taught me the importance of regular bar maintenance.

• Data and Insights: Regular bar maintenance can extend the life of your bar by as much as 50%. It also improves cutting performance and reduces the risk of accidents.

• Cost: A bar groove cleaner costs around $5-$10. A flat file costs around $10-$15. Bar and chain oil typically costs around $10-$15 per gallon. A chainsaw bar rail dresser tool costs around $20-$30.

Hack #4: Wood Type and Cutting Techniques – Matching the Saw to the Task

Different types of wood have different densities and characteristics, which can affect cutting performance. Choosing the right cutting technique for the wood type is crucial for smooth, efficient cuts.

• Understanding Wood Types:

  • Softwoods: Softwoods, such as pine, fir, and cedar, are generally easier to cut than hardwoods. They are less dense and contain more resin.
  • Hardwoods: Hardwoods, such as oak, maple, and hickory, are denser and more difficult to cut. They require a sharper chain and more power.
  • Green Wood vs. Seasoned Wood: Green wood is freshly cut wood that has a high moisture content. It is generally easier to cut than seasoned wood, but it can also be more prone to binding. Seasoned wood has been dried and has a lower moisture content. It is more stable and less prone to warping, but it can be harder to cut.

• Cutting Techniques:

  1. Felling: Felling is the process of cutting down a tree. It requires careful planning and execution to ensure the tree falls in the desired direction.

  2. Limbing: Limbing is the process of removing branches from a felled tree. Use caution when limbing, as branches can spring back and cause injury.

  3. Bucking: Bucking is the process of cutting a felled tree into shorter lengths. Use proper techniques to avoid pinching the chain.

  4. Boring Cut: A boring cut involves plunging the tip of the bar into the wood to create a hole. This technique is useful for felling large trees and for removing knots.

  5. Pinching: Pinching occurs when the weight of the wood closes in on the chain, causing it to bind. To avoid pinching, use wedges to keep the cut open.

• Pro Tips for Wood Type and Cutting Techniques:

  • Use the Right Chain: Use a chain that is appropriate for the type of wood you are cutting. For example, a chain with a more aggressive cutter is better for hardwoods.
  • Keep the Chain Sharp: A sharp chain is essential for cutting any type of wood.
  • Use Proper Body Positioning: Maintain a stable stance and keep your body out of the line of the cut.
  • Plan Your Cuts: Before making a cut, think about how the wood will react and plan your cuts accordingly.
  • Use Wedges: Use wedges to keep the cut open and prevent pinching.
  • Avoid Cutting Dirty Wood: Cutting dirty wood can dull the chain quickly.

• My Experience: I was once bucking a large oak log that was lying on the ground. I didn’t use wedges to keep the cut open, and the weight of the log caused the chain to pinch. The saw became stuck, and I had to use a come-along to free it. This experience taught me the importance of using wedges and planning my cuts carefully.

• Case Study: Felling a Leaning Tree: I once had to fell a large pine tree that was leaning precariously towards a building. This required careful planning and execution. I used a combination of felling cuts and wedges to ensure the tree fell in the desired direction, away from the building. The key was to create a hinge that would control the direction of the fall.

• Data and Insights: Using the correct cutting technique can increase cutting efficiency by as much as 25%. It also reduces the risk of accidents and damage to the saw.

• Cost: Wedges typically cost around $10-$20 each. A come-along costs around $50-$100.

Hack #5: Saw Maintenance – Keeping Your Stihl MS 391 in Top Shape

Regular maintenance is essential for keeping your Stihl MS 391 running smoothly and efficiently. Neglecting maintenance can lead to poor performance, increased wear and tear, and potentially costly repairs.

• Essential Maintenance Tasks:

  1. Cleaning the Air Filter: A clean air filter is essential for proper engine performance. Clean the air filter regularly with compressed air or a brush. Replace the air filter if it is damaged or excessively dirty.

  2. Cleaning the Spark Plug: A clean spark plug ensures proper ignition. Clean the spark plug with a wire brush and check the gap. Replace the spark plug if it is worn or fouled.

  3. Cleaning the Cooling Fins: The cooling fins on the engine cylinder help dissipate heat. Keep the cooling fins clean to prevent overheating.

  4. Checking the Fuel Filter: A clogged fuel filter can restrict fuel flow and cause the engine to run poorly. Replace the fuel filter regularly.

  5. Checking the Chain Brake: The chain brake is a safety device that stops the chain quickly in the event of kickback. Ensure the chain brake is functioning properly.

  6. Lubricating Moving Parts: Lubricate all moving parts of the chainsaw regularly with grease or oil.

  7. Sharpening the Chain Regularly: As mentioned, keep the chain sharp for efficient cuts.

• Pro Tips for Saw Maintenance:

  • Use Fresh Fuel: Use fresh, high-quality fuel and oil mix. Old fuel can degrade and cause engine problems. I always use fuel stabilizer in my gas cans to prevent fuel from going bad.
  • Follow the Manufacturer’s Recommendations: Follow the manufacturer’s recommendations for maintenance intervals and procedures.
  • Store the Saw Properly: When not in use, store the saw in a dry place to prevent rust and corrosion.
  • Inspect Regularly: Regularly inspect the chainsaw for any signs of damage or wear.

• My Experience: I once neglected to clean the air filter on my chainsaw, and it became clogged with sawdust. This caused the engine to run poorly and eventually overheat. I had to take the saw to a repair shop, which was an unnecessary expense. This experience taught me the importance of regular air filter maintenance.

• Data and Insights: Regular saw maintenance can extend the life of your chainsaw by as much as 30%. It also improves performance and reduces the risk of breakdowns.

• Cost: An air filter costs around $5-$10. A spark plug costs around $5-$10. Fuel stabilizer costs around $5-$10 per bottle. A chainsaw maintenance kit, which includes various filters and spark plugs, costs around $20-$30.

Next Steps: Putting These Hacks into Action

Now that you’re armed with these five pro hacks, it’s time to put them into practice. Here’s a roadmap for getting started:

1. Sharpen Your Chain: If you haven’t sharpened your chain recently, start there. A sharp chain is the foundation of smooth cutting.

2. Check Chain Tension: Ensure your chain is properly tensioned before each use.

3. Maintain Your Bar: Clean the bar groove, file the rails, and lubricate the bar regularly.

4. Match the Saw to the Task: Choose the right cutting technique for the type of wood you are cutting.

5. Maintain Your Saw: Perform regular maintenance tasks, such as cleaning the air filter and spark plug.

By implementing these five pro hacks, you’ll be well on your way to achieving smooth, efficient cuts with your Stihl MS 391. Remember, practice makes perfect. The more you use your chainsaw and apply these techniques, the better you’ll become at mastering it.

And finally, always prioritize safety. Wear appropriate personal protective equipment (PPE), including a helmet, eye protection, hearing protection, gloves, and chainsaw chaps. Read and understand your chainsaw’s owner’s manual before using it.

Happy cutting!

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