Every chainsaw will eventually need servicing and replacement of its parts. You need to use exactly the right ones, too–chainsaws are very dangerous if improperly fit. In this guide, we’ll review important measurements of your chainsaw and how to properly size the bar and chain for replacement.
Finding exactly the right part is critical for your chainsaw, but the huge variety of models and parts means you can’t depend upon standard sizes. For example, one prominent manufacture makes over 80 different configurations to match unique requirements of this hardworking tool.
Because of this, precise measurements are necessary to ensure the right fit when replacing parts on your chainsaw. Manufacturers’ charts can be intimidating, and some owners resort to a local dealer to determine the correct sizing. This is a bit of overkill, however: you can avoid hassle and expense by taking the measurements yourself.
There are several key measurements to obtain. The key dimensions are bar or blade length, link count, gauge and pitch size. Each element is interconnected and necessary.
First: Check your Chainsaw Specs
To potentially save time and effort, check your equipment and documentation before starting. The information you need might be stamped onto the blade or casing. Some manufacturers use model numbers to encode the necessary measurements, and in that case, you’ll need to consult the owner’s manual to decipher its code.
Dimensions are usually placed near the base of the mounted bar. If you can find the pitch, gauge, and link count, you’ll have all the information you need to replace your chain. To replace the bar there are a few other things to know, as explained below.
How to take chainsaw measurements
Before taking any measurements involving the chain or guide bar, make sure the unit is turned off. Also, make sure the chainsaw cannot restart by finding the spark plug … and unplugging it.
How to Measure the Guide Bar
A chainsaw’s guide bar, or blade, is measured differently than its chain. The bar’s length has 2 basic dimensions: cutting and true length. The true length is the length of the actual blade. To find that figure simply remove the housing and measure the full length of the bar.
The guide bar’s cutting length is also referred to as the called length. It measures the part of the guide bar that is visible. The called length is the dimension you need for replacement.
There are many guide bars on the market, but the most common are 16, 18, and 20 inches. In rare accord, manufacturers standardized their bar/blade lengths into 2-inch increments, which makes replacement much easier. This is why rounding up is part of the blade measuring process explained below.
- Steady the chainsaw on a flat surface, and begin measuring from the edge of the casing where the guide bar fits into the unit’s housing.
- Measure to the furthest tip. This figure will usually be from 12 to 20 inches.
- Round the measurement up to the nearest inch. The rounded-up number is the called length of your blade.
How to Measure Pitch Size
A chainsaw’s pitch is the spacing between the rivets on its chain. Rivets are the small pins or studs that make up the chain. The pitch must match the teeth of the sprocket that drives the chain.
The method has 2 parts: measure the distance between any 3 consecutive rivets on the chain, and then divide the result by 2. A larger pitch measurement usually means a bigger, heavier chain.
Be aware you will need to be very precise in measuring the pitch. This is the most exacting of the necessary measurements, and the one that you might consider letting a dealer handle if you’re unsure.
How to Take a Link Count
Another necessary metric for chain replacement is the number of drive links, or lugs, in the chain. This requires only a simple count.
One easy method is to mark a link and count as you feed the chain around the bar until it comes up again. If the chain isn’t mounted on the bar, another method is to lay the chain flat and line up the links on each side—this way you can count 2 links at a time.
The only caveat is to make sure you’re counting drive links and not rivets. Here’s a short video that illustrates what drive links look like and how they fit into the chain.
How to measure the chain gauge
A chain’s gauge measures the thickness of its drive links. The dimension is equal to the width of the groove of your guide bar, and is usually written in thousandths of an inch.
The chain’s gauge and the bar’s groove must match for proper lubrication and a smooth glide. Thicker gauge measurements are usually stronger but heavier.
The common way to measure gauge is by using a digital caliper. If you’re using a common size, there is a convenient method to determine the gauge by using coins. To do this, alternately try to insert a penny, a quarter, and a dime in the guide bar groove, and see which one slides into the groove without force.
Interpret the results according to these measures:
Penny (.058 gauge)
Quarter (.063 gauge)
Dime (.050 gauge)
Replacing parts on a chainsaw can be frustrating. The unique dimensions and how they are determined are unusual, and the available choices are vast and always changing. It’s not about finding the strongest chain or bar, you need to determine the exact size that fits.
With the information we’ve covered, you can take accurate measurements to replace either the chain or bar for your chainsaw. Just use care and common sense, and you can eliminate extra cost … and the frustration.