How to sharpen a chainsaw chain correctly

Chain sharpening for STIHL chainsaws is a service we carry out routinely at Zakservices in Senica. What you want: sharp cutters of equal length, the right angle (typically 30° on standard STIHL chains), the right round file diameter for the pitch and a depth gauge checked after sharpening. The chain should pull itself into the cut with light pressure and throw out chips, not fine dust.

Below you’ll find a practical guide to touching up the chain at home, based on STIHL’s own principles. If you don’t have the right file or file guide, or you’re unsure about the angle and the condition of the guide bar, bring your saw to Obchodná 493/2A. We’ll sharpen the chain, check the guide bar and lubrication and, if needed, advise you on a replacement. Just call +421 904 446 915 or +421 34 651 70 72, or email zakservices@zakservices.sk.

What you’ll learn in this article

• when a chain is blunt and what to do about it (the signs, according to STIHL)
• which file and angle to use (the basics, according to STIHL)
• a step-by-step checklist if you sharpen at home
• how to check the depth gauge and why it matters
• the most common mistakes and safety
• when to leave it to the Zakservices workshop, and FAQ

Chain sharpening as a service in Senica

At our shop at Obchodná 493/2A, we’ll sharpen your STIHL chainsaw chain, check the pitch and the condition of the guide bar, and show you a suitable file with a file guide if you’d like to do the maintenance yourself. Just drop in during opening hours (Monday to Friday, 8:30 to 16:30) or give us a quick call first.

When it makes sense to come in straight away:

• you don’t know the pitch, the chain type or the file diameter
• the cutters are uneven after hitting a stone or a nail
• the saw cuts crooked, vibrates, smokes or runs hot even after an attempt at sharpening
• you’d like a first demonstration of the method on your own STIHL saw
• you’d rather leave the sharpening and the guide bar check to the workshop

A touch-up at home still makes sense for ordinary dulling, as long as you have the right tools and some patience. The aim of this article is to show you what to do at home and when it’s safer and quicker to come to us.

When to sharpen the chain

Sharpen sooner rather than later. A blunt chain puts strain on the engine, the guide bar, the sprocket and the operator, and according to STIHL it’s also less safe. With STIHL chains, a simple rule applies: as soon as the cutting gets worse, give the cutters a quick touch-up rather than a ‘rough’ sharpen once a season.

Typical signs that it’s time to sharpen (according to STIHL manuals):

1. The cut produces fine dust instead of coarser chips.
2. You have to push into the cut. A sharp chain ‘pulls’ itself into the wood.
3. The saw cuts crooked or pulls to one side (often because the left and right cutters are unevenly sharp or of different lengths).
4. The cut produces smoke, even though lubrication and tension are fine.
5. The saw bounces and vibrates as you cut (chatter) and is hard to keep in the cut.
6. After contact with sand, stone, nails or soil, the edge goes quickly. In that case, sharpen straight away, even after a short job.

A practical rhythm, according to STIHL: doing 2 to 3 light strokes per cutter more often is better than one big regrind. After a longer session cutting firewood, check a few cutters. After working in sand or dust, sharpen more often. If you’re not sure, bring the saw to Zakservices and we’ll assess its condition together.

What you need before sharpening

For standard STIHL chains, a simple kit is all you need. Check the exact file diameter against the chain pitch and the saw’s manual. In our shop in Senica, we’ll help you choose the file, file guide and gauge to suit the chain on your saw.

Basic kit:

• a round file of the right diameter, made for saw chains (not an ordinary workshop file)
• a file guide / file holder (helps you hold the angle and height)
• a flat file for the depth gauges
• a filing gauge / depth gauge tool for the chain pitch in question
• optionally, a 2-in-1 kit (such as the STIHL Easy File), which files the cutters and the depth gauge at the same time
• cut-resistant gloves, eye protection
• a sturdy stand or vice to clamp the guide bar, a soft brush, a marker pen to mark the reference cutter

Guide table of round file diameters according to STIHL (code on the depth gauge):

If the marking is illegible, measure the pitch: take the distance between the centres of three consecutive rivets and divide it by two (for example, 19.05 mm means a 3/8" pitch). Measuring across two gaps is more accurate and matches the manufacturers’ definition. The pitch alone doesn’t identify the chain, though (3/8" and 3/8" Picco have the same pitch but are not interchangeable), so also compare the marking on the guide bar, or we can check it for you at Zakservices. Don’t guess the diameter by eye. A file that’s too thick changes the shape of the cutter. One that’s too thin gouges the cutting edge incorrectly.

File angle and height (the basics)

On standard STIHL chains, the cutters are generally sharpened at an angle of 30° to the guide bar. Hold the file horizontally (at 90° to the side of the guide bar). About one fifth of the file’s diameter should protrude above the top plate of the cutter. The exception: STIHL Rapid Hexa chains are sharpened at 25°. For other exceptions, follow the manual for your STIHL chain.

Important rules for the filing stroke:

• file only on the forward stroke, lifting the file on the way back
• apply pressure from the inside of the cutter outwards
• don’t file the tie straps or the drive links
• rotate the file now and then so that it doesn’t wear on one side
• all the cutters should end up the same length (file them to match the shortest)
• a sharp cutter has an even shine along the edge (if patches stay dull or ‘blotchy’, it isn’t finished yet)

A STIHL file guide reduces the risk of a crooked angle. If it’s your first time, it’s a sensible aid. In the shop, we’ll show you what suits your pitch, or we’ll sharpen the chain for you.

Checklist: how to sharpen step by step

Take your time. A quick sharpen ‘by eye’ often costs you more time later, on the guide bar and the engine, than a slow, correct touch-up. If you want to be sure of the geometry and the guide bar, have us sharpen the chain the first time and watch how it’s done.

1. Switch off the engine and let the saw come to a complete stop. On STIHL cordless models, remove the battery. On petrol models, disconnect the spark plug boot as the manual says. On mains-powered models, unplug the cable.
2. Clamp the guide bar in a vice or a sturdy stand. Wear gloves and eye protection. Release the chain brake so that you can move the chain freely (after switching off and disconnecting the power).
3. Tension the chain slightly more while you sharpen so that the cutters don’t ‘wobble’. After sharpening, set the tension back as the manual says.
4. Brush the chain and guide bar clean of sawdust, resin and sand. Check for damage and whether the cutters have reached the wear mark. If they have, it’s better to replace the chain.
5. Find the shortest or most damaged cutter and mark it with a marker pen. It sets the number of strokes for the other cutters. Optionally, colour the top of the cutter: after 2 to 3 strokes, the colour should disappear evenly.
6. Fit the file guide for the correct pitch and angle (usually 30°). Place the file so that it rests on the cutter as the holder is designed to position it.
7. File the reference cutter with a few straight forward strokes (often 2 to 5 light strokes for a routine touch-up, more if it’s damaged). Count the strokes.
8. Work along all the cutters on one side with the same number of strokes. Then turn the saw round by 180° and do the other side the same way.
9. Check the cutter lengths. They should be as even as possible. Large differences cause vibration and a risk of damaging the chain. If one side is shorter, even up the longer cutters with one or two strokes.
10. Check the depth gauges with the filing gauge (see the next section) and lower them with the flat file if necessary. With a 2-in-1 kit, the depth gauge is adjusted at the same time as the cutter.
11. Check the lubrication and the condition of the guide bar (groove, oil hole, wear on the rails). After sharpening or replacing the chain, turn the guide bar over so that it wears evenly.
12. Before the first cut, set the tension back, check the oil, start the saw as the manual says and make a test cut in clean wood.

The depth gauge: why it decides how the chain cuts

The depth gauge (the guiding hump in front of the cutter) determines how deep the cutter can bite into the wood. The difference in height between the top plate of the cutter and the depth gauge sets the bite. As you sharpen the cutters, this difference gets smaller. If the depth gauge stays too high, the chain skids and takes less wood. If you file it too low, the bite becomes aggressive and the risk of kickback increases.

How to go about it:

1. Once all the cutters are sharpened, place the filing gauge for the pitch in question on the chain.
2. If the depth gauge protrudes above the gauge, lower it with a flat file (not a round one), filing horizontally down to the level of the gauge.
3. Adjust all the depth gauges the same way.
4. Slightly round off the front corner of the depth gauge back to its original shape, following the service mark / the manual. Don’t lower the top point any further.
5. On chains with a ‘humped’ drive link (some STIHL chains), lower the depth gauge and the hump together, as the manual says. Filing this part incorrectly can increase the tendency to kick back.
6. Take care that the flat file doesn’t touch the freshly sharpened cutting edge.

Guide values for the depth gauge setting according to STIHL (always check with the gauge and the manual):

• 1/4 P: about 0.45 mm
• the common pitches 1/4, .325, 3/8 and 3/8 Picco: often around 0.65 mm
• .404: about 0.80 mm

These figures are a guide, not a substitute for the gauge. At Zakservices, we’ll show you the right gauge for your STIHL chain, or we’ll adjust the depth gauges when we sharpen the chain in the workshop.

Safety when sharpening and when working with a sharp chain

According to STIHL, a sharp chain is safer than a blunt one, because you push less and have better control of the cut. The following always applies:

• engine off, ignition disconnected, battery removed or cable unplugged
• chain brake released while sharpening (so that the chain can be moved), and the brake used as the manual says when working with the saw running
• gloves and eye protection (flying sawdust and metal filings)
• the saw held firmly in a vice or stand, no loose sharpening ‘on your knee’
• correct tension before sharpening and before cutting
• after sharpening, check the guide bar lubrication and the condition of the sprocket
• keep a firm stance when cutting, avoid the tip of the guide bar (risk of kickback) and don’t cut into the ground or stones
• if you’re tired or the chain ‘jumps’, stop and check the tension, the cutting edges and the guide bar

If you’re new to STIHL chainsaws, it’s better to leave the first sharpening to the Zakservices workshop and have us show you how it’s done.

The most common sharpening mistakes

• The wrong file diameter, or an ordinary workshop file instead of a chain file. The result is a weak or aggressive cut and faster wear.
• A crooked angle (not 30°, or not what the chain type requires, such as 25° for Rapid Hexa). The saw pulls to one side and cuts slowly.
• Filing on the return stroke too. The file wears out and the edge gets ‘torn’.
• A different number of strokes on the left and right. Uneven cutters mean a crooked cut.
• Ignoring the depth gauge. Sharp cutters with a high depth gauge still cut badly.
• A depth gauge that’s too low. An aggressive bite and a higher risk of kickback.
• Sharpening a slack or dirty chain. The angle and height ‘wander’.
• Carrying on with damaged cutters after hitting a stone or a nail. You need to file all the cutters down to match the shortest, or replace the chain.
• A neglected guide bar and oil. Even a sharp chain works badly on a dry or worn guide bar.

If the cut still isn’t right after you’ve tried at home, drop in to see us in Senica. Often all it takes is correcting the geometry, adjusting the depth gauge or replacing a worn guide bar.

When to replace the chain or have it serviced instead of sharpening it

A touch-up at home makes sense as long as the chain is intact and you have the right tools. Come to Zakservices in Senica especially when:

• you want chain sharpening as a service, without worrying about the angle and the depth gauge
• the cutters are damaged by an impact (a stone, a nail, a fence) and their lengths differ significantly
• you don’t know the pitch, the chain type or the right file
• the chain is already worn short (cutters at the wear mark), or has loose rivets or cracks
• the saw vibrates, pulls, smokes or runs hot even after sharpening
• the guide bar has an uneven groove, worn rails or poor oil flow
• the sprocket is badly worn (in which case replacing just the chain isn’t enough)
• you’d like a first demonstration on your STIHL and a check of your file set

In the workshop, we check the chain, guide bar, tension and lubrication. Sometimes it’s better value to fit a new STIHL chain and dress the guide bar than to try to save ruined cutters. For guidance: we confirm the specific price and stock in person, as there’s no price list on the website.

Quick comparison: at home or in the workshop

Frequently asked questions (FAQ)

1. Do you sharpen chainsaw chains at Zakservices?

Yes. In Senica, we sharpen STIHL chainsaw chains and check the depth gauge, guide bar and lubrication. Just bring in your saw or call +421 904 446 915 or +421 34 651 70 72.

2. How often should I sharpen my chainsaw chain?

When the cutting gets worse, not by the calendar. According to STIHL, it’s better to sharpen little and often. With clean wood, a quick touch-up after a larger batch of firewood is often enough. After working in sand or close to the ground, sharpen straight away.

3. What sharpening angle should I use on STIHL chains?

On standard STIHL chains, the typical angle is 30°. Hold the file horizontally in relation to the guide bar. The Rapid Hexa exception: 25°. For other exceptions, follow the manual for the specific chain.

4. How do I find the right file diameter?

Look at the code on the cutter’s depth gauge and the STIHL table (for example, code 2 = .325" = 4.8 mm, code 6 = 3/8" Picco = 4.0 mm). If you’re not sure, we’ll check it at Zakservices using the chain on your saw.

5. Do I always have to adjust the depth gauge?

Yes, check it after sharpening the cutters. If it protrudes above the gauge, lower it with a flat file. Without checking the depth gauge, the cut often stays weak even with sharp cutters. A 2-in-1 kit adjusts the depth gauge at the same time as the cutter.

6. Why does the saw cut crooked even after sharpening?

The most common causes are unevenly sharpened left and right cutters, the wrong angle, a worn guide bar or incorrect tension. Check that you used the same number of strokes on both sides and the condition of the guide bar, or have the chain evened up in the workshop.

7. Can I use an electric sharpener instead of a file?

For home maintenance, a round file with a file guide is the safest option. Electric sharpeners take practice, and one mistake can quickly ruin the geometry of the cutters. If you’re not experienced, stick to sharpening by hand or use the Zakservices workshop.

8. When should I stop sharpening the chain and replace it?

When the cutters are at the wear mark, the rivets are damaged or there are cracks, or when the cut still isn’t steady even after correct sharpening and a guide bar check. At that point, a new STIHL chain and a check of the guide bar and sprocket give a safer result.

9. Why should the chain brake be released when sharpening?

So that you can move the chain freely and sharpen the next cutters. But always switch off the engine first and disconnect the battery, cable or ignition. Don’t confuse using the brake while the saw is running with the maintenance procedure.

Let us help you at Zakservices in Senica

If you need your chain sharpened, your guide bar checked or help choosing a file and file guide, bring your STIHL chainsaw to Zakservices. We’ll show you how it’s done, sharpen the chain or suggest a replacement. We sell and service machines in Senica.

Zakservices, s.r.o.
Obchodná 493/2A, 905 01 Senica (white building opposite the Kaufland car park)
Phone: +421 904 446 915, +421 34 651 70 72
Email: zakservices@zakservices.sk
Opening hours: Monday to Friday, 8:30 to 16:30
Website: https://www.zakservices.sk

Please check the seasonal Saturday opening (April to June) by phone. We’ll confirm specific accessories, indicative prices and stock with you in person.