Understanding Your Chainsaw Bar and Chain
The bar and chain are the heart of every chainsaw’s cutting system. The University of Hawaii’s CTAHR bulletin describes the guide bar as the part that “supports and provides track for saw chain.” The saw chain itself is a loop made up of cutters, depth gauges (also called rakers), connecting links, and drive links. Greenworks operator manuals add that the drive links ride inside the bar groove while the cutters do the actual wood removal. Getting to know these parts helps you choose the right replacement, keep the saw cutting safely, and avoid premature wear. For a broader look at chainsaw types and features, see our Chainsaws & Pole Saws guide.
Anatomy of the Bar and Chain
The table below lists the key components, what each one does, and what to inspect during routine care. All descriptions are drawn from the University of Hawaii CTAHR bulletin and Greenworks operator manuals.
| Part | What it does | What to check |
|---|---|---|
| Guide bar | Supports and provides a track for the saw chain (Hawaii CTAHR). | Clean the groove and oil holes; look for nicks, bends, or uneven wear; turn the bar periodically if it is symmetrical (Hawaii CTAHR, Greenworks). |
| Saw chain (cutters, depth gauges, drive links) | A loop of cutters with depth gauges, connecting links, and drive links (Hawaii CTAHR). | Check cutter sharpness, depth gauge height, drive link wear, and overall chain tension (Greenworks, CCOHS). |
| Drive links | Fit into the bar groove and engage the sprocket (Greenworks). | Inspect for wear or hammering; the height must not touch the bottom of the groove (Greenworks, CCOHS). |
| Cutters | The cutting edges that remove wood. | Sharpen with a round file at the angles specified in the owner’s manual; dull cutters produce fine sawdust instead of chips (Hawaii CTAHR, Greenworks). |
| Depth gauges (rakers) | Control how much wood each cutter removes (Hawaii CTAHR). | Check height with a flat file; lowering the depth gauge too much can increase kickback (Greenworks, CCOHS). |
| Bar groove | The channel that holds the drive links (Greenworks). | Remove sawdust and debris with a wire, narrow stick, or scraping hook (Hawaii CTAHR, Greenworks). |
| Oil holes | Allow bar and chain oil to reach the chain (Hawaii CTAHR). | Clean the holes at the rear of the bar so oil flow is not blocked (Hawaii CTAHR, Greenworks). |
| Sprocket nose | The exposed end of the bar that contains a sprocket (Hawaii CTAHR). | Lubricate the nose sprocket bearings if the bar has them (Greenworks). |
Matching a Replacement Bar and Chain
Chainsaw bars and chains are not universal. Greenworks operator manuals warn, “Only use replacement guide bars and saw chains specified by the manufacturer. Incorrect replacement guide bars and saw chains may cause chain breakage and/or kickback.” The Hawaii CTAHR bulletin similarly advises studying the owner’s manual for details about your specific brand and model. Manuals list the chain pitch and gauge your saw takes, along with bar length. For example, the Greenworks 40V 14-inch chainsaw manual lists a chain pitch of 3/8″ LP and a gauge of .050″, while the 82V 20-inch model uses a 0.325″ pitch and .050″ gauge. Always match the pitch, gauge, and bar length printed in your manual. If you are shopping for a battery-powered saw, our Battery Chainsaw Guide for Homeowners explains what to look for in voltage, bar length, and chain specs.
Chain Tension: Why It Matters and How to Adjust
A slack chain can jump off the bar and cause serious injury (Greenworks), and the Hawaii bulletin lists running the chain too tight or too loose among the conditions that cause bar wear. The Hawaii bulletin recommends checking chain tension frequently. To adjust, first shut off the saw and wear gloves. Loosen the sprocket cover nuts, lift the nose of the guide bar, and pull the chain away from the top of the bar. The chain is properly tensioned when it does not sag and can be moved freely along the bar by a gloved hand. Tighten the chain-tensioning screw while holding the bar upward, then secure the cover nuts (Hawaii CTAHR).
Greenworks manuals note that a chain stretches as it heats up. The drive links of a correctly tensioned warm chain will hang approximately 1/16 inch (1.58 mm) out of the bar groove. The CCOHS suggests adjusting tension after the saw has been in use for five to ten minutes. Always recheck tension after the first few cuts and periodically throughout the work session. For a complete maintenance routine, see our Chainsaw Maintenance: Chain, Bar, Oil and Tension article.
Bar Maintenance: Cleaning, Turning, and Wear Checks
Regular bar care extends the life of both the bar and chain. The Hawaii bulletin says to turn the bar over periodically if it is symmetrical, which helps keep wear even. After removing the bar, clean the groove with a wire or narrow stick to clear out sawdust and debris, and clean the oil inlet holes at the rear of the bar. Nicks on the bar rails can be filed smooth, and slight bends can often be straightened. Greenworks manuals add that you should lubricate the nose sprocket bearings (if present) with a syringe, use a scraping hook to clean the groove, and remove burrs from the edges with a flat file. Replace the bar if the groove no longer fits the drive links (the links must never touch the bottom) or if the inside of the guide bar is worn enough to make the chain lean to one side (Greenworks). The CCOHS also recommends replacing a bar that is nicked or distorted.
Sharpening Basics: Cutters and Depth Gauges
A dull chain makes fine sawdust instead of chips, causes the bar to overheat, produces curved cuts, and forces the operator to push harder (Hawaii CTAHR). The Hawaii bulletin advises filing a little each time and filing often. Cutters and depth gauges are designed to be filed at specific angles with round, flat, or triangular files, depending on the chain; the correct file sizes and angles are given in the owner’s manual. The CCOHS states that you need two files: a round file of uniform diameter for the cutters and a flat file for the depth gauges. It also recommends checking the depth gauges every third or fourth time you sharpen the chain.
As an example, the Greenworks 40V 14-inch chainsaw manual specifies a 5/32 inch (4 mm) diameter round file for the cutters and a flat file for the top plate, side plate, and depth gauge. The same manual says to replace the chain if the cutting edges are shorter than 1/5 inch (5 mm), if there is too much space between the drive links and rivets, or if repeated sharpening no longer improves cutting speed. Always file all cutters to the same length and maintain the manufacturer’s recommended angles. Lowering the depth gauge too far can increase the risk of kickback (Greenworks).
Low-Kickback Chain and Safety
Kickback occurs when the nose or tip of the guide bar contacts an object or when the wood pinches the chain, throwing the bar rapidly back toward the operator (Greenworks). The Hawaii bulletin lists low-kickback chain as one of the principal features to evaluate for reducing kickback, along with a chain brake, low-kickback bars, and a safety tip. Using a low-kickback chain can help homeowners work more safely, but it does not replace proper cutting technique. Always wear appropriate protective equipment; our Chainsaw Protective Gear: What to Wear guide covers the essentials. If you are deciding between gas and battery power, our Battery vs Gas vs Corded Garden Tools comparison can help you weigh the trade-offs.
Frequently asked questions
How often should I check chain tension?
Check the tension before each use and again after the first few minutes of cutting. The chain stretches as it heats up. The CCOHS recommends adjusting tension after the saw has been in use for five to ten minutes. The Hawaii bulletin says to check tension frequently throughout operation.
What do chain pitch and gauge mean?
They are chain specifications that must match what your saw’s manual lists; manuals give them alongside bar length. For instance, the Greenworks 40V 14-inch chainsaw manual lists a 3/8″ LP pitch and .050″ gauge. Always refer to your owner’s manual for the correct values.
Can I use any bar and chain on my chainsaw?
No. Greenworks manuals explicitly state that only replacement bars and chains specified by the manufacturer should be used. Incorrect parts can cause chain breakage or kickback. The Hawaii CTAHR bulletin also advises studying the owner’s manual for details about your specific model.
For more guidance on choosing and using chainsaws, visit our Chainsaws & Pole Saws page.
