Hollow Grind Vs Flat Grind Woodworking Tools – Your Ultimate Guide

ByJim Boslice Woodworking Tool

A hollow grind creates a concave bevel using a grinding wheel, which makes honing the edge on a flat stone much faster. It’s ideal for tools that need a razor-sharp edge, like bench chisels and plane irons.

A flat grind creates a straight, V-shaped bevel that is stronger and more durable. It’s better for tools that endure more impact, such as mortise chisels, axes, and many knives.

Ever pick up a chisel and feel like you’re pushing a dull rock through wood? You put in the effort, but the tool fights you every inch of the way, leaving a torn, messy surface instead of a clean shaving.

We’ve all been there. The secret to effortless, satisfying woodworking isn’t brute force—it’s a truly sharp edge. But the world of sharpening can feel confusing, especially when you hear terms like “hollow grind” and “flat grind.”

I promise this guide will clear up that confusion for good. We’ll break down the hollow grind vs flat grind woodworking tools debate into simple, practical terms. You’ll learn what each grind is, when to use it, and how to create it yourself.

By the end of this article, you’ll have the knowledge to put a frighteningly sharp and durable edge on your tools, making your time in the shop more productive and enjoyable.

What is a Tool’s “Grind”? Understanding the Bevel

Before we dive into the specifics, let’s get on the same page about what a “grind” actually is. It’s simpler than it sounds.

Look at the cutting edge of your chisel or plane iron. The angled surface that slopes down to create the sharp point is called the primary bevel.

The “grind” simply refers to the shape of that primary bevel. Is it curved or is it flat? That single difference is the entire basis of our discussion, and it has a huge impact on how the tool performs and how you sharpen it.

The Hollow Grind: The Secret to Fast Honing

A hollow grind is exactly what it sounds like: the primary bevel is slightly concave, or “hollowed out.”

Think about it this way: if you press a flat chisel against a round grinding wheel, the wheel will remove more metal from the middle of the bevel than from the top and bottom, creating a subtle curve.

How a Hollow Grind is Created

The hollow grind is a direct result of using a bench grinder. The curve of the grind perfectly matches the radius of the grinding wheel you used to shape it.

This is the fastest way to establish a primary bevel on a new tool or to fix a badly damaged edge. A few minutes at the grinder can save you an hour of tedious work on sharpening stones.

Benefits of a Hollow Grind for Woodworkers

The main advantage of a hollow grind isn’t its cutting performance, but its incredible efficiency during sharpening. This is a key part of our hollow grind vs flat grind woodworking tools guide.

  • Faster Honing: Because the bevel is concave, only two narrow points touch your sharpening stone: the very tip of the edge (the “toe”) and the back of the bevel (the “heel”). You’re removing a tiny amount of steel, making honing incredibly fast.
  • Easy Angle Registration: It’s much easier to feel when the tool is sitting correctly on the stone. The two points of contact create a stable base, helping you maintain a consistent angle by hand.
  • Achieves a Keen Edge: The thinner profile right behind the cutting edge allows for a very low cutting angle, resulting in a razor-sharp tool perfect for taking fine shavings.

Common Problems with Hollow Grinds

Of course, there’s a trade-off. That fine edge comes at a cost.

The biggest drawback is that the edge is more fragile. With less steel supporting the cutting tip, it’s more prone to chipping or fracturing, especially when working with tough, knotty hardwoods or performing heavy-duty tasks like chopping out mortises.

The Flat Grind: The Champion of Durability

A flat grind is the most straightforward grind. The primary bevel is a single, perfectly flat plane running from the back of the bevel straight to the cutting edge.

This creates a classic, strong “V” shape that provides maximum support directly behind the cutting edge.

How a Flat Grind is Created

A true flat grind is typically established using flat abrasive surfaces. This can be done with a belt sander (like a knife-maker would use), coarse diamond plates, or sandpaper on a flat surface like granite or float glass.

Most woodworkers, however, end up with a flat grind through repeated honing of a hollow-ground tool. Over time, as you flatten the two contact points on your stones, the hollow disappears and you’re left with a flat bevel.

Benefits of a Flat Grind for Woodworking Tools

The flat grind is all about strength. Here are the main benefits of hollow grind vs flat grind woodworking tools when it comes to durability.

  • Maximum Edge Strength: The solid wedge of steel directly behind the edge makes it incredibly robust and resistant to chipping.
  • Excellent for Tough Jobs: It’s the preferred grind for tools that take a beating, like mortise chisels, framing chisels, and axes.
  • Long-Lasting: A well-honed flat grind can hold its edge for a long time during demanding work, requiring less frequent sharpening.

Common Problems with Flat Grinds

The strength of a flat grind comes with a downside: it’s a lot more work to maintain.

Sharpening a flat grind is much slower because you have to remove metal from the entire face of the bevel, not just two small points. It also requires more skill or a reliable honing guide to maintain a perfectly consistent angle.

Hollow Grind vs Flat Grind Woodworking Tools: A Head-to-Head Comparison

So, which one is right for you? Let’s break down the hollow grind vs flat grind woodworking tools best practices in a simple comparison.

Speed of Sharpening

For establishing a bevel, the grinder (hollow grind) is fastest. For the final honing process on stones, the hollow grind wins by a landslide. You can refresh the edge on a hollow-ground chisel in under a minute.

Edge Durability

The flat grind is the clear winner here. The extra steel behind the edge provides superior support and prevents chipping. If your tool’s edge is constantly failing, a flat grind (or a higher sharpening angle) might be the solution.

Ease of Honing by Hand

The hollow grind is much easier for beginners to hone by hand. The two points of contact act like training wheels, making it simple to lock in the correct angle on your water stone or diamond plate.

Best Tool Applications

This is where the rubber meets the road. Choosing the right grind for the right tool is key.

  • Use a Hollow Grind for: Bench chisels, paring chisels, plane irons (for smoothing and jointer planes), and spokeshave blades. These are tools used for fine slicing and shaving.
  • Use a Flat Grind for: Mortise chisels, framing chisels, axes, hatchets, and most carving knives. These tools need to withstand impact and pressure.

How to Achieve Each Grind in Your Workshop

Ready to get sharpening? Here’s a practical look at how to hollow grind vs flat grind woodworking tools in your own shop.

Creating a Hollow Grind with a Bench Grinder

A bench grinder is an essential tool for serious sharpening. A slow-speed wet grinder is ideal as it prevents overheating the steel, but a standard high-speed grinder works well with a light touch.

  1. Safety First: Always wear safety glasses. Make sure the grinder’s guards are in place.
  2. Dress the Wheel: Use a diamond wheel dresser to ensure the face of your grinding wheel is flat and clean. This is a critical step for a clean, consistent grind.
  3. Set the Angle: Adjust the tool rest to your desired primary bevel angle, typically 25 degrees for most chisels and plane irons.
  4. Grind Carefully: Rest the tool flat on the tool rest and gently bring it into contact with the spinning wheel. Move the tool from side to side across the wheel to ensure an even grind and prevent heat buildup.
  5. Quench Often: Keep a pot of water nearby and dip the tool in it every few seconds to keep the steel cool. If you see the metal change color (to blue or straw), you’ve overheated it and ruined the temper.
  6. Check for a Burr: Continue grinding until you feel a small burr (a tiny wire of metal) form along the entire length of the cutting edge. This tells you that you’ve successfully shaped the bevel all the way to the tip.

The Hybrid Approach: The Best of Both Worlds

Here’s the pro tip: most experienced woodworkers don’t strictly use one or the other. They use a hybrid system.

First, they establish a 25-degree hollow grind at the bench grinder. Then, they go to their sharpening stones and add a slightly steeper secondary bevel (or “micro-bevel”) at around 30 degrees. This final bevel is a tiny flat grind right at the tip.

This method gives you the durability of a stronger cutting angle combined with the lightning-fast honing of a hollow grind. When you sharpen, you’re only polishing that tiny micro-bevel, which takes just a few seconds.

Best Practices and Care Guide for Your Grinds

A good edge is easy to maintain if you follow a few simple rules. This hollow grind vs flat grind woodworking tools care guide will help you keep your tools in top shape.

Maintaining Your Hollow Grind

As you repeatedly hone the micro-bevel on a hollow-ground tool, the two “flats” at the heel and toe will get wider. Once they become too wide, honing will slow down considerably.

When you notice this happening, it’s time to go back to the grinder to re-establish the hollow and start the process over. This is typically only necessary after 10-20 honings.

A Note on Sustainable and Eco-Friendly Sharpening

Thinking about sustainable hollow grind vs flat grind woodworking tools practices? The most eco-friendly thing you can do is care for the tools you have.

Proper sharpening extends the life of a tool indefinitely. A quality chisel from your grandfather’s time, when properly ground and honed, will perform just as well as a new one. By maintaining your tools, you avoid the waste of replacing them. Using water stones, which use water as a lubricant instead of oil, is also a cleaner, more environmentally friendly choice for your workshop.

Frequently Asked Questions About Hollow Grind vs Flat Grind Woodworking Tools

Can I put a hollow grind on a knife?

You can, but it’s generally not recommended for general-purpose or outdoor knives. The hollow grind creates a very thin, delicate edge that is great for slicing but can easily chip or roll if used for prying, chopping, or cutting hard materials. Most kitchen and utility knives use a flat grind for durability.

How often should I re-grind my chisel?

You only need to go back to the grinder for two reasons: 1) The edge has a significant nick or chip that would take too long to remove on stones, or 2) You’ve honed the micro-bevel so many times that the flats have become too large and honing is no longer quick and easy.

What’s a “micro-bevel” and how does it relate to these grinds?

A micro-bevel is a very narrow, secondary bevel applied at a slightly steeper angle than the primary bevel. It’s the final step in sharpening. Adding a 30-degree micro-bevel to a 25-degree hollow grind is a very popular and effective technique that gives you a strong edge that is also fast to touch up.

Do I need an expensive slow-speed wet grinder?

No, but they make the process safer and easier. A standard high-speed “dry” grinder works perfectly well, but you must be extremely careful not to overheat the steel. A light touch and frequent quenching in water are essential. A slow-speed wet grinder runs the wheel through a water bath, keeping the tool cool automatically.

Understanding the difference between a hollow grind and a flat grind is a huge step toward mastering the art of sharpening. It transforms a frustrating chore into a quick, satisfying process.

Remember the key takeaway: use a hollow grind to quickly shape your fine-cutting tools like chisels and planes, then hone a tiny micro-bevel for a durable, razor-sharp edge. For your heavy-duty tools, a sturdy flat grind is your best bet.

Now get out in the shop, put these tips into practice, and experience the joy of working with a truly sharp tool. Stay safe and build something incredible!

Jim Boslice
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