What Is A Jointer Woodworking Tool Used For – The Secret To Flat
A jointer is a woodworking machine used to create a perfectly flat face on one side of a board.
It is also used to mill a perfectly square edge that is precisely 90 degrees to that flat face, which is the critical first step for almost any furniture or cabinetry project.
Ever grab a stack of lumber from the home center, excited to start a new project, only to find the boards are twisted, bowed, or cupped?
You try to build a tabletop, but the edges won’t meet flush, leaving ugly gaps that no amount of glue or clamps can fix. It’s a universal frustration that separates amateur-looking work from professional craftsmanship.
In this guide, we’re going to solve that fundamental problem. We’ll show you exactly what is a jointer woodworking tool used for and how this one machine can transform your woodworking. You’ll gain the confidence to turn rough, unpredictable boards into perfectly flat and square stock—the true foundation of quality building.
We’ll cover the core benefits a jointer brings to your shop, provide a step-by-step guide on how to use it safely, and share tips for troubleshooting common issues. Let’s get your projects started on the right foot—or rather, the right face.
What Exactly is a Jointer and How Does It Work?
At its core, a jointer is a simple machine designed to do one thing with incredible precision: make wood flat and straight. It looks like two small tables with a spinning cutterhead nestled between them.
Here’s the basic anatomy:
- Infeed Table: This is where you place the board to begin the cut. It’s set just slightly lower than the cutterhead.
- Cutterhead: A rapidly spinning cylinder with sharp knives (or cutters) that shaves off wood.
- Outfeed Table: This table is set at the exact same height as the highest point of the cutterhead knives. It supports the newly flattened portion of the board.
- Fence: A tall, flat guide (usually cast iron) that can be set to a perfect 90-degree angle to the tables.
The magic happens as you push a board across the infeed table and over the cutterhead. The blades remove a small amount of material, and the newly milled, perfectly flat surface then rests on the outfeed table. By referencing this flat outfeed table for the rest of the pass, the jointer shaves off all the high spots, leaving a truly flat face.
The Two Critical Jobs of a Jointer: Why Every Workshop Needs One
A jointer performs two foundational tasks that are essential for precision woodworking. Think of it as creating the first two sides of a perfect rectangle. Without these first two perfect surfaces, it’s impossible to get the other sides right with a table saw or planer.
Job #1: Face Jointing – Creating the First Flat Surface
This is the starting point for milling any piece of lumber. Face jointing removes cups, bows, and twists from the widest part of a board.
You place the concave side (the “cup” down) on the jointer tables. As you pass it over the cutterhead, it shaves away the high points until the entire face is perfectly flat. This first flat face becomes your primary reference surface for every other cut you make on that piece of wood.
Job #2: Edge Jointing – Squaring an Edge to the Flat Face
Once you have one flat face, you can create a perfectly square edge. This is crucial for creating seamless glue-ups for tabletops, cabinet doors, and panels.
To do this, you press the newly flattened face firmly against the jointer’s fence, which you’ve already set to a perfect 90 degrees. Then, you run the board’s edge over the cutterhead. Because the flat face is held tight to the square fence, the resulting edge will be exactly 90 degrees to it.
A Step-by-Step Guide: How to Use a Jointer Safely and Effectively
A jointer is a powerful tool that demands respect and a proper technique. Following this simple what is a jointer woodworking tool used for guide will ensure clean results and, more importantly, keep you safe.
Safety First: Essential Jointer Best Practices
Before you even turn the machine on, run through this safety checklist. These are non-negotiable rules for operating a jointer.
- Wear Your PPE: Safety glasses are a must. Hearing protection is highly recommended, as jointers are loud. Avoid loose clothing, gloves, or jewelry that could get caught.
- Use Push Blocks: Always use push blocks or push pads, especially when face jointing. They keep your hands high above the cutterhead and provide better control and even pressure.
- Mind the Board Size: Never attempt to joint a board that is shorter than 12 inches long. It’s unstable and dangerous. Also, avoid jointing wood that is excessively thin (less than 1/2 inch).
- Take Shallow Passes: Set your depth of cut to 1/16″ or less for general work, and 1/32″ for hardwoods or figured grain. Deeper cuts increase the risk of tear-out and kickback.
The Jointing Process: From Rough Sawn to Perfection
Here is how to what is a jointer woodworking tool used for in a step-by-step process:
- Inspect the Board: Check the grain direction. You want to feed the board so the knives are cutting “downhill” with the grain to prevent tearing. Identify any major twists or cups.
- Set the Depth of Cut: Adjust the infeed table for a shallow pass. Remember, multiple light passes are safer and produce a better finish than one heavy pass.
- Face Joint the Board: Place the board’s concave (cupped) side down on the infeed table. Using your push blocks, apply even downward pressure and guide the board smoothly over the cutterhead. Don’t stop mid-cut.
- Check for Flatness: After a few passes, turn the machine off and use a reliable straightedge to check the board’s face. Hold it corner-to-corner and edge-to-edge. If you see any light underneath, you need another pass.
- Check the Fence: Use a high-quality machinist’s square to ensure your fence is set to a perfect 90 degrees relative to the outfeed table. Adjust if necessary.
- Edge Joint the Board: Place the newly flattened face firmly against the fence. Use one hand to keep it pressed to the fence and the other (with a push block) to feed it forward. The result will be a perfectly square edge.
Once you have one flat face and one square edge, you can take the board to your thickness planer and table saw to mill it to final dimensions.
Benefits of What is a Jointer Woodworking Tool Used For in Your Shop
Integrating a jointer into your workflow unlocks a new level of quality and potential in your projects. The benefits of what is a jointer woodworking tool used for extend far beyond just making wood flat.
- Flawless Glue-Ups: With perfectly square and straight edges, your boards will meet seamlessly. This creates stronger joints and invisible glue lines for professional-looking tabletops and panels.
- Stronger Joinery: Accurate joinery, like mortise and tenon or box joints, starts with square stock. A jointer ensures your components fit together tightly and accurately.
- Save Money on Lumber: You can buy cheaper, rough-sawn lumber and mill it yourself to perfection. This is significantly more cost-effective than buying pre-surfaced (S4S) lumber from big box stores.
- Unleash Your Creativity: By milling your own stock, you are no longer limited to the standard dimensions sold in stores. You can create custom thicknesses and work with unique wood species.
- The Foundation of Precision: A jointer is the first step in the milling process. It provides the reference surfaces needed for the planer and table saw to work accurately.
Troubleshooting Common Problems with What is a Jointer Woodworking Tool Used For
Even with perfect technique, you might run into a few issues. Here are some common problems with what is a jointer woodworking tool used for and how to fix them.
Why is My Board Tapered or Snipped?
Snipe is when the jointer takes a deeper cut at the very beginning or end of a board. This is almost always caused by an improperly set outfeed table.
The Fix: The outfeed table must be exactly level with the highest point of the cutterhead knives. If it’s too low, the board will drop onto the knives as it leaves the infeed table, causing snipe. Adjust it carefully until it’s perfectly co-planar.
Why Isn’t My Edge 90 Degrees?
You jointed an edge, but when you check it with a square, it’s off. This is a simple setup issue.
The Fix: Your fence is not perfectly 90 degrees to the tables. Unplug the machine, place a reliable square on the outfeed table against the fence, and adjust the fence until there is no gap. Then lock it down and check its positive stops.
Why Am I Getting Tear-Out?
Tear-out is when the wood grain gets ripped out, leaving a rough, chipped surface instead of a glassy-smooth one.
The Fix: This has a few potential causes. First, you might be feeding the board against the grain. Flip the board end-for-end and try again. Second, your knives might be dull and need sharpening or replacing. Finally, you might be taking too deep a cut, especially in figured wood like curly maple.
Jointer Care and Sustainable Woodworking Practices
A well-maintained tool is a safe and effective tool. This simple what is a jointer woodworking tool used for care guide will keep your machine running smoothly for years, while also touching on some eco-friendly benefits.
Your Jointer Care Guide: Keeping it Tuned Up
Regular maintenance is key. Clean the tables and fence frequently to remove dust and resin buildup, which can affect accuracy. Apply a coat of paste wax to the tables to prevent rust and help boards glide smoothly.
Periodically check your knives for nicks or dullness. Sharp knives produce the best results and are safer to use. And every few months, re-check that your tables are co-planar and your fence is square.
Eco-Friendly Jointing: Making the Most of Your Materials
One of the best aspects of a jointer is its role in sustainable what is a jointer woodworking tool used for practices. It allows you to salvage and use lumber that might otherwise be considered scrap due to warping or twisting.
It also empowers you to buy lumber from local, sustainable sawmills. This rough-sawn wood often has a much smaller carbon footprint than lumber shipped across the country. Plus, the shavings produced by a jointer are perfect for garden compost or animal bedding, ensuring nothing goes to waste.
Frequently Asked Questions About Using a Jointer
What’s the difference between a jointer and a planer?
This is the most common question! They are partner machines. A jointer creates one flat face and one square edge (your two reference surfaces). A thickness planer then takes that board, references the flat face, and cuts the opposite face parallel to it, bringing the board to its final thickness.
Can I use a jointer on end grain?
No, absolutely not. This is extremely dangerous. The cutterhead will catch the vertical wood fibers, causing the wood to shatter violently and kick back at you. Never joint the end grain of a board.
Do I really need a jointer? Can I use a hand plane or a sled instead?
For speed and repeatability, a jointer is unmatched. However, you can achieve the same results with other methods. A skilled woodworker can flatten boards with a set of hand planes. For those with a table saw or router, you can build a “jointer sled” that allows you to flatten one face and create a straight edge. These are great alternatives for hobbyists on a budget or with limited space.
How wide of a jointer do I need?
For most home workshops, a 6-inch jointer is a fantastic starting point and will handle the majority of project needs. An 8-inch model provides much more capacity for wider boards and is a great upgrade if your budget and space allow. The wider the jointer, the wider the board you can face-joint in a single pass.
The jointer isn’t just another tool; it’s the gateway to a higher level of woodworking. It’s the machine that takes the wild, unpredictable nature of wood and brings it into the world of precision and control.
By mastering this one machine, you’re not just flattening boards—you’re laying the foundation for every successful project that follows. You’re ensuring tight joints, seamless panels, and a final product you can be truly proud of.
Now go flatten some boards and build something amazing. Stay safe in the shop!
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