Who This Suits
The Granberg Bar-Mount Chain Sharpener, Model 12, is a specialized tool designed for users who sharpen chains frequently in the field. It mounts directly to the chainsaw bar, uses a diamond wheel, and runs off a 12V battery. There is no need to remove the chain or haul a bench grinder into the woods. This review covers its performance across a range of chainsaw sizes, from 16-inch bars to 36-inch ripping chains, based on owner feedback and spec analysis.
Performance: The Good and the Not So Good
Sharpening on the Bar is a Game Changer
The primary advantage is not having to remove the chain from the saw. This saves significant time compared to a bench grinder, which requires pulling the clutch cover, removing the bar, taking the chain off, mounting it in a vice, sharpening, and reassembling. With the Granberg, the guide mounts on the bar, the knob tightens, and sharpening begins in about 30 seconds.
On a 20-inch bar, filing by hand typically takes 4 to 5 minutes for a decent touch-up. The Granberg completes the same chain in about 2 minutes. The consistency is also superior: the diamond wheel hits every cutter at the same angle and depth, eliminating guesswork between 30 and 32 degrees.
The Diamond Wheel: Built to Last
The grinding wheel is a diamond electroplated wheel, not a cheap aluminum oxide stone that wears down quickly. Owners consistently report sharpening the same chain over 15 times with no visible wear, glazing, chipping, or loss of grit. In comparison, traditional grinding wheels on bench grinders may burn through three in the same period. The diamond wheel cuts fast and cool, and does not load up with resin from the chain, even on chains with heavy pitch buildup. Cleaning the wheel with a pink pencil eraser after every few sharpenings takes five seconds.
Battery Power: Freedom from the Cord
This sharpener runs on 12V DC and comes with a cigarette lighter plug and alligator clips. Using a standard 7 amp-hour sealed lead acid battery, it runs for over 45 minutes of continuous use before the motor slows down, enough to sharpen a dozen chains. This allows sharpening in the field—on a logging landing, in a driveway, or at a remote farm. The small DC motor has plenty of torque for sharpening cutters but bogs down if pushed too hard, which prevents burning the edge of the cutter. Light pressure is recommended.
The Speed Trade Off
The Granberg Model 12 is slower than a dedicated AC-powered bench grinder. A bench grinder spins at 3,450 RPM, while the Granberg spins at approximately 200 RPM under load. A bench grinder can zip through a chain in about 60 seconds, whereas the Granberg takes 2 to 3 minutes for the same chain. This is because multiple light passes are required; the diamond wheel removes material slowly. On a severely damaged chain with rolled edges, it takes about 5 minutes per side to restore a consistent profile.
This is not a deal breaker for most users, as spending 3 minutes sharpening in the field is preferable to 10 minutes removing, sharpening, and reinstalling the chain. However, for production cutters who sharpen 10 chains every night, a bench grinder is more suitable. The Granberg is designed for touch-ups and field work.
Build Quality and Value
All Metal Construction
Granberg tools are known for robust construction. The Model 12 features a cast aluminum main body, a steel guide plate that clamps to the bar, and metal adjustment knobs. It feels heavy and durable. The mounting system is simple: slide the guide plate over the bar, tighten a knob, and the sharpener locks in place. It works on bars from 1/4 inch to 3/8 inch gauge and accommodates different groove depths. It fits Stihl, Husqvarna, Oregon, and Cannon bars perfectly.
The grinding head pivots to adjust the filing angle from 0 to 45 degrees, with positive detents that click into place. Setting it to 30 degrees for most chains holds reliably. The depth gauge (raker) adjustment uses a screw that limits how deep the wheel can go, maintaining consistent cutter length.
What is in the Box
The package includes the sharpener head, bar mount clamp, 12V power cord with alligator clips, 12V cigarette lighter plug, and a small bottle of lubricating oil. A 12V battery is not included. The sharpener does not come with a case; it ships in a cardboard box. The price is higher than a basic file guide but lower than a good bench grinder. The build quality justifies the cost for a specialized tool that sharpens chains on the bar with a diamond wheel. Granberg has been making this design for decades, and it is a proven product.
Potential Issues
Minor complaints include the 6-foot power cord, which is fine if the battery is close but short for milling setups. An extension can be made using a 12V extension cord from a car accessory store. There is no built-in light, making sharpening at dusk difficult without a headlamp. The raker adjustment works but is less precise than a dedicated raker file; many owners still use a flat file to set raker depth.
Who Should Buy This Sharpener
- Milling Operators: Essential for Alaskan mill or chainsaw mill users who sharpen constantly. Not having to remove the chain saves hours.
- Landscapers and Arborists: Allows field sharpening on a truck tailgate without returning to the shop.
- People with Arthritis or Hand Pain: The tool does the work; turning a crank is much easier on hands than filing.
- Anyone Who Wants Consistent Angles: Locks in the angle, eliminating the challenge of holding a file at the same angle every time.
- People Who Hate Removing the Chain: Minimizes saw disassembly.
Verdict
The Granberg Bar-Mount Chain Sharpener Model 12 is a durable, specialized tool for field sharpening. It is not a replacement for a bench grinder for high-volume sharpening, but it excels for touch-ups and on-the-go use. The diamond wheel lasts indefinitely and cuts cleanly. Battery power enables sharpening anywhere. Build quality is excellent. While slower than a bench grinder and requiring a separate 12V battery, the convenience of on-bar sharpening outweighs these downsides for most users. It is a tool that will last a lifetime.
Final Score: 4 out of 5 stars. Loses a star for the lack of a built-in light and short power cord, but performance and build are solid.
