You'll find a bench grinder in the shop of just about every engineer, auto restorer, woodworker, and DIY enthusiast. They are an easy-to-use tool for all kinds of shaping and sharpening tasks, and you can expand their versatility by fitting them with wire or polishing wheels. We've been assessing the latest models, and our concise guide explains the features you need to consider. We've also made a few recommendations. Our top pick, the Jet 8" Bench Grinder, is a reliable, heavy-duty model, ideal for the high-output environments of demanding professionals.
A bench grinder is in essence a very basic machine: an electric motor with two horizontal shafts, each carrying an abrasive wheel of a different degree of coarseness (grit). Tool rests and eye shields are added. Standard sizes (given as the diameter of the abrasive wheels) are 6" or 8". Generally they run at around 3,500 rpm. Wheels are typically 36- and 60-grit, made of silicon carbide.
Models with 3" and 4" wheels are designed for delicate work and may also offer a flexible shaft (like those found with rotary tools). These are preferred by engravers and jewelers. They can run as high as 10,000 rpm.
Slow-speed grinders, which run at around 1,700 rpm, are preferred for sharpening knives and chisels because they usually have white aluminum oxide wheels, which are a finer grit and run cooler (high temperatures take the temper out of blades). There are high-end versions of this grinder that run with one wheel in a water bath. At the other end they have a leather honing wheel.
There are also variable speed bench grinders available -- you can attach a coarse wheel to one end, and a fine sharpening wheel to the other. However, they don't usually run slow enough to satisfy fine woodworkers.
As we've said, jewelers and other fine trades prefer a smaller model. Woodturners and carvers will prefer slow speed versions. For everyone else, the main factors are wheel size and power.
A 6" bench grinder is a good general-purpose tool. If you're fixing an old vehicle or sharpening a mower blade, it's all you need. An 8" grinder is usually pro-grade. Wheels are wider for faster cutting, and they have more powerful motors. The whole machine will be larger, so if your shop is short of space you'll need to check external dimensions.
Motor power is indicated as either amps (A) or horsepower (HP), which can be confusing. There's a formula to do the math to convert one to the other, but it's a bit complicated. Suffice it to say that anything from 2 to 4 amps is a light-duty model, a 1/2 HP model is a pretty powerful all-rounder, and a 1HP model is a professional tool.
Other than that, you'll want to look at how easy it is to adjust guards and guides, just from a convenience point of view. Cast iron construction usually indicates quality. It's not just tough and durable, but the added weight helps damp vibration.
The least-expensive bench grinders are 3" and 4" models with flexible shaft attachments and basic light-duty 6" models. These can be found for around $50. More powerful 6" models start at about $100, with 8" versions and slow-speed grinders for $150 plus, though it's not difficult to pay $300 or more for professional-grade equipment. High-end precision sharpening systems can be over $900.
A. Although guards are provided, they don't provide total coverage, so some form of eye protection is recommended. If you're grinding metal (rather than sharpening something with a handle), it can get very hot, so wear suitable gloves.
A. Bolt it down to prevent movement. Wait until it reaches full speed before using, and don't be tempted to rub anything against the wheel just to slow it down. If a wheel is cracked or wobbling, turn it off immediately. Rectify or replace before continuing.
What we like: Immensely powerful 1HP motor. 36- and 60-grit 8" wheels offer good versatility. Quick-adjusting guides and guards. Durable construction provides great stability. Rubber foot minimizes vibration. Two-year warranty.
What we like: Easy-to-change wheels are 3/4" wide at 36- and 60-grit to cover lots of household and shop tasks. Adjustable tool rests and guards. Useful work light included.
What we like: Smooth, relatively quiet 1/2 HP motor. 1" aluminum oxide wheels make it easier to get a keen edge. Two different grits. Good vibration damping. Stable base.
Automatic Polishing Machine
Bob Beacham is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money. BestReviews never accepts free products from manufacturers and purchases every product it reviews with its own funds.
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