3/8 LP File Size Guide (5 Chain Saw Filing Tips)

Ever found yourself wrestling with a chainsaw that just won’t cut straight, spitting sawdust instead of slicing through wood like butter? I know I have. More often than I care to admit, the culprit wasn’t a dull chain, but a poorly filed one. And the key to a properly filed chain, especially on those popular 3/8″ low profile (LP) chainsaws, lies in understanding the correct file size and technique. This guide is going to be your go-to resource for mastering chainsaw chain filing, specifically for 3/8″ LP chains. I’ll share my experiences, the mistakes I’ve made, and the hard-earned lessons that have transformed me from a chainsaw-chain-filing fumbler to a confident wood processor.

3/8 LP File Size Guide: 5 Chain Saw Filing Tips

This guide will cover everything you need to know about filing your 3/8″ LP chainsaw chain, from selecting the right file to mastering the filing technique. We’ll dive into the specifics of 3/8″ LP chains, the importance of correct file size, and the step-by-step process I use to keep my chains cutting smoothly and safely.

What is a 3/8″ Low Profile (LP) Chainsaw Chain?

Before we grab a file, let’s understand what we’re working with. A 3/8″ LP chain, also sometimes referred to as 3/8″ Picco, is a common type of chain found on many smaller and mid-sized chainsaws, particularly those used by homeowners and hobbyists. The “3/8” refers to the pitch of the chain, which is the distance between three consecutive rivets divided by two. The “LP” or “Low Profile” designation indicates a lower profile cutter, which generally translates to reduced kickback and easier handling, making them ideal for limbing and smaller diameter trees.

Key Characteristics of 3/8″ LP Chains:

Pitch: 3/8″ (9.52mm)
Gauge: Typically .050″ (1.3mm) or .043″ (1.1mm) – this refers to the thickness of the drive links that fit into the guide bar groove.
Common Applications: Homeowner chainsaws, limbing, pruning, carving.
Advantages: Reduced kickback, easier to handle, suitable for smaller chainsaws.
Disadvantages: Slower cutting speed compared to larger chains.

Think of my experience a few years back. I was helping a friend clear some storm damage using my trusty Stihl MS 170 (a typical 3/8″ LP chainsaw). The chain was dull, and I, in my youthful ignorance, grabbed any old file I had lying around. The result? An unevenly filed chain that cut poorly and vibrated excessively. That experience taught me the hard way the importance of using the correct file size and technique.

Why is the Correct File Size Crucial?

Using the wrong file size can lead to several problems, including:

Incorrect Cutting Angle: The file’s diameter determines the angle at which the cutter is sharpened. An incorrect angle can result in aggressive but weak cutters that dull quickly, or cutters that simply won’t bite into the wood.
Uneven Cutter Lengths: Using the wrong file can lead to inconsistent cutter lengths, causing the chain to pull to one side or vibrate excessively.
Damage to the Cutter: A file that is too large can damage the cutter’s top plate and side plate, weakening it and reducing its lifespan. A file that is too small may not effectively sharpen the cutter.
Increased Kickback Risk: Incorrectly filed cutters can increase the risk of kickback, a dangerous phenomenon where the chainsaw suddenly jumps back towards the operator.

I once witnessed a colleague use a file that was way too large for his 3/8″ LP chain. The result was a chain that was so aggressively sharpened that it chattered and vibrated violently, making it nearly impossible to control the chainsaw. He ended up ruining the chain and nearly injuring himself. This underscores the critical need for precision in chain filing.

Finding the Right File Size for your 3/8″ LP Chain

The recommended file size for a 3/8″ LP chain is typically 5/32″ (4.0mm). However, it’s always best to consult your chainsaw’s manual or the chain manufacturer’s specifications to confirm the correct file size for your specific chain.

Here’s how to confirm the correct file size:

Consult your chainsaw manual: This is the most reliable source of information.
Check the chain packaging: The file size is often printed on the chain packaging.
Use a chain filing gauge: These gauges have slots for different file sizes, allowing you to quickly determine the correct size for your chain.

My Personal Recommendation: While 5/32″ (4.0mm) is the most common size, I always double-check my chainsaw manual or the chain packaging. I keep a small notebook with the file sizes for each of my chainsaws, so I don’t have to look it up every time. This simple practice has saved me a lot of time and frustration.

Tools You’ll Need

Before you start filing, make sure you have the following tools:

Round File (5/32″ or 4.0mm): This is the most important tool. Invest in a high-quality file for best results. I prefer files made by Stihl or Oregon, as they tend to hold their edge longer.
Flat File: Used for filing the depth gauges (rakers).
Depth Gauge Tool: This tool ensures that the depth gauges are filed to the correct height.
Chain Filing Guide (Optional): This guide helps maintain the correct filing angle and depth. I recommend using one, especially if you’re a beginner.
Vise or Chain Filing Clamp: This securely holds the chainsaw bar in place while you file. A simple bench vise works well, or you can purchase a dedicated chain filing clamp.
Gloves: Protect your hands from sharp cutters and metal filings.
Eye Protection: Safety glasses or goggles are essential to protect your eyes from flying debris.
Wire Brush: Used to clean the chain before filing.

A Word on Tool Quality: Don’t skimp on your tools. A cheap file will dull quickly and make filing more difficult. A high-quality file will last longer and produce a sharper, more consistent edge. I learned this the hard way after wasting money on a set of bargain-bin files that were practically useless.

5 Chain Saw Filing Tips: A Step-by-Step Guide

Now, let’s get to the heart of the matter: filing your 3/8″ LP chain. Here’s my step-by-step guide, incorporating the lessons I’ve learned over the years:

Step 1: Preparation is Key

Clean the Chain: Use a wire brush to remove any dirt, sawdust, or oil from the chain. A clean chain is easier to file and will extend the life of your file. I often use compressed air to blow out any remaining debris.
Secure the Chainsaw: Place the chainsaw bar in a vise or chain filing clamp. Make sure the bar is securely held in place to prevent it from moving while you file.
Identify the Shortest Cutter: Examine the cutters on the chain. You’ll likely find that some are shorter than others due to wear or previous filing. This is normal. Start by filing the shortest cutter first, as this will determine the final length of all the other cutters. I use a marker to identify the shortest cutter so I don’t lose track.

Step 2: Filing the Cutters

Position the File: Hold the round file at the correct angle. The angle is typically marked on the chain filing guide, or you can refer to your chainsaw’s manual. For a 3/8″ LP chain, the top plate angle is usually around 30 degrees, and the side plate angle is around 60 degrees.
File with a Smooth, Even Stroke: Using a smooth, even stroke, file the cutter from the inside out. Apply gentle pressure on the forward stroke and release pressure on the return stroke. Avoid rocking the file or applying excessive pressure.
Maintain the Correct Depth: File until the cutter is sharp and the cutting edge is even. Use the chain filing guide to maintain the correct depth and angle. I usually aim for 2-3 strokes per cutter, but this will vary depending on the sharpness of the file and the condition of the chain.
File All Cutters to the Same Length: After filing the shortest cutter, use it as a reference and file all the other cutters to the same length. This is crucial for ensuring that the chain cuts straight and evenly. I frequently check the cutter lengths with my eye to ensure consistency.
Alternate Sides: File all the cutters on one side of the chain, then flip the chainsaw bar and file the cutters on the other side. This helps maintain balance and prevents the chain from pulling to one side.

Step 3: Filing the Depth Gauges (Rakers)

Determine the Correct Depth Gauge Setting: The depth gauges (also known as rakers) control how much the cutter bites into the wood. If the depth gauges are too high, the chain won’t cut effectively. If they’re too low, the chain will be too aggressive and prone to kickback. The correct depth gauge setting is typically specified in your chainsaw’s manual.
Use a Depth Gauge Tool: Place the depth gauge tool over the cutter and the depth gauge. If the depth gauge protrudes above the tool, it needs to be filed down.
File the Depth Gauges: Using a flat file, carefully file down the depth gauges until they are flush with the top of the depth gauge tool. Be careful not to file them too low.
Round Off the Front of the Depth Gauges: After filing the depth gauges, use the flat file to slightly round off the front of each depth gauge. This helps prevent the depth gauges from catching on the wood and causing kickback.

Step 4: Check Your Work

Inspect the Cutters: Examine the cutters to ensure that they are all the same length and that the cutting edges are sharp and even.
Check the Depth Gauges: Verify that the depth gauges are all set to the correct height and that they are slightly rounded off at the front.
Rotate the Chain: Rotate the chain around the bar and check for any tight spots or binding. A properly filed chain should rotate smoothly and freely.

Step 5: Final Touches

Lubricate the Chain: Before using the chainsaw, lubricate the chain with chainsaw oil. This will help reduce friction and extend the life of the chain.
Test the Chain: Start the chainsaw and test the chain on a piece of wood. A properly filed chain should cut smoothly and aggressively, producing large, even chips.

My Personal Tips for Success:

Practice Makes Perfect: Don’t be discouraged if your first few attempts at filing are not perfect. It takes practice to develop the necessary skills and feel.
Use a Chain Filing Guide: A chain filing guide can be a valuable tool, especially for beginners. It helps maintain the correct filing angle and depth, ensuring consistent results.
Keep Your Files Clean: Clean your files regularly with a file card to remove any metal filings that may be clogging the teeth.
Replace Dull Files: A dull file will make filing more difficult and less effective. Replace your files when they start to lose their edge. I usually replace my files after every 5-10 chains.
Sharpen Frequently: Sharpen your chain frequently, rather than waiting until it’s completely dull. A slightly dull chain is much easier to sharpen than a severely dull one. I usually sharpen my chain after every tank of fuel.

Case Study: Reviving a Neglected Chainsaw Chain

I once inherited a neglected chainsaw from a neighbor who was moving. The chain was severely dull, with several broken cutters and uneven depth gauges. Most people would have simply replaced the chain, but I saw it as a challenge.

Here’s what I did:

Assessment: I carefully examined the chain to assess the damage. I identified the shortest cutter and noted the condition of the depth gauges.
Repairing Broken Cutters: I used a chain breaker and spinner to remove the broken cutters and replace them with new ones. This is a more advanced technique, but it can save you money in the long run.
Filing the Cutters: I filed all the cutters to the same length, using the shortest cutter as a reference. I paid close attention to maintaining the correct filing angle and depth.
Filing the Depth Gauges: I filed the depth gauges to the correct height, using a depth gauge tool. I also rounded off the front of each depth gauge.
Testing: After filing the chain, I tested it on a piece of wood. The chain cut smoothly and aggressively, producing large, even chips.

The result? I was able to revive a seemingly useless chain and save myself the cost of a new one. This experience reinforced my belief that with patience and the right techniques, even the most neglected chainsaw chain can be restored to its former glory.

Safety First: Protecting Yourself While Filing

Chain filing involves working with sharp tools and potentially dangerous equipment. Always follow these safety precautions:

Wear Eye Protection: Safety glasses or goggles are essential to protect your eyes from flying debris.
Wear Gloves: Gloves will protect your hands from sharp cutters and metal filings.
Work in a Well-Lit Area: Good lighting will help you see what you’re doing and avoid mistakes.
Keep Your Work Area Clean: A clean work area will reduce the risk of accidents.
Disconnect the Spark Plug: Before working on the chainsaw, disconnect the spark plug to prevent accidental starting.
Be Aware of Your Surroundings: Make sure there are no people or pets nearby while you’re filing.
Take Breaks: Filing can be tiring. Take breaks to avoid fatigue and maintain focus.

I always make sure to wear a full face shield when filing, as I’ve had metal filings ricochet off the chain and come dangerously close to my eyes. It’s better to be safe than sorry.

Strategic Advantages of a Sharp Chain

Beyond the immediate benefit of easier cutting, a sharp chainsaw chain offers several strategic advantages:

Increased Efficiency: A sharp chain cuts faster and more efficiently, allowing you to complete your work in less time.
Reduced Fuel Consumption: A sharp chain requires less power to cut, resulting in reduced fuel consumption.
Less Wear and Tear on the Chainsaw: A sharp chain puts less stress on the chainsaw engine and components, extending its lifespan.
Improved Safety: A sharp chain is less likely to kick back, making it safer to operate.
Higher Quality Results: A sharp chain produces cleaner, more precise cuts, resulting in higher quality results.

I’ve noticed a significant difference in fuel consumption when using a sharp chain versus a dull one. With a sharp chain, I can typically cut through a cord of wood on a single tank of fuel, whereas with a dull chain, I might need two or even three tanks. This translates to significant savings in fuel costs over time.

Understanding Wood Types and Their Impact on Chain Maintenance

The type of wood you’re cutting can significantly impact the lifespan of your chainsaw chain. Different wood species have different densities and abrasive properties, which can affect how quickly the chain dulls.

Here’s a brief overview of common wood types and their impact on chain maintenance:

Softwoods (Pine, Fir, Spruce): Softwoods are generally easier to cut and less abrasive than hardwoods. Chainsaw chains tend to stay sharp longer when cutting softwoods.
Hardwoods (Oak, Maple, Ash): Hardwoods are denser and more abrasive than softwoods. Chainsaw chains dull more quickly when cutting hardwoods.
Green Wood: Green wood (freshly cut wood with high moisture content) is often easier to cut than seasoned wood, but it can also be more prone to clogging the chain with sap and fibers.
Seasoned Wood: Seasoned wood (wood that has been dried) is harder and more abrasive than green wood. Chainsaw chains dull more quickly when cutting seasoned wood.
Dirty Wood: Wood that is covered in dirt, sand, or bark can be extremely abrasive and will dull a chainsaw chain very quickly.

I once made the mistake of cutting a pile of old fence posts that were covered in dirt and sand. The chain was dull after just a few cuts. I learned my lesson and now always clean the wood as much as possible before cutting it.

Drying Methods and Moisture Content Targets

Properly drying firewood is essential for efficient burning and reducing smoke. The drying process reduces the moisture content of the wood, making it easier to ignite and burn.

Here are some common drying methods:

Air Drying: This is the most common and cost-effective method. The wood is stacked in a well-ventilated area and allowed to dry naturally.
Kiln Drying: This method uses a kiln to dry the wood quickly and efficiently. Kiln-dried wood has a lower moisture content than air-dried wood.
Solar Drying: This method uses the sun’s energy to dry the wood. Solar drying is more efficient than air drying but less efficient than kiln drying.

Moisture Content Targets:

The ideal moisture content for firewood is between 15% and 20%. Wood with a moisture content above 20% will be difficult to ignite and burn inefficiently, producing excessive smoke.

I use a moisture meter to check the moisture content of my firewood before burning it. This ensures that I’m burning wood that is properly dried and will burn efficiently. You can buy a decent moisture meter for around $30-$50.

Conclusion: Mastering the Art of Chain Saw Filing

Mastering the art of chainsaw chain filing is an essential skill for anyone who works with wood. By understanding the principles of chain filing and following the steps outlined in this guide, you can keep your chainsaw chain cutting smoothly and safely, saving you time, money, and frustration. Remember, practice makes perfect, so don’t be discouraged if your first few attempts are not perfect. Keep practicing, and you’ll soon become a confident and skilled chainsaw chain filer.

Next Steps

Now that you’ve learned the basics of chainsaw chain filing, here are some practical next steps you can take:

Gather Your Tools: Assemble the necessary tools, including a round file, flat file, depth gauge tool, chain filing guide (optional), vise or chain filing clamp, gloves, and eye protection.
Inspect Your Chainsaw Chain: Examine your chainsaw chain to assess its condition and identify any damage or wear.
Practice Filing: Practice filing your chainsaw chain on a piece of scrap wood. Pay close attention to maintaining the correct filing angle and depth.
Test Your Work: After filing your chainsaw chain, test it on a piece of wood to ensure that it cuts smoothly and aggressively.
Seek Feedback: Ask an experienced chainsaw user to review your filing technique and provide feedback.

By taking these steps, you can continue to develop your chainsaw chain filing skills and become a proficient wood processor. Happy cutting!

3/8 LP File Size Guide (5 Chain Saw Filing Tips)

3/8 LP File Size Guide: 5 Chain Saw Filing Tips