October 11, 2023

Troubleshooting Jointer Issues: Why is Your Jointer Not Flattening Wood?

You’re not alone if your jointer isn’t flattening wood as it should. In this blog post, we’ll dive into troubleshooting jointer issues, uncover common problems, and help you achieve perfectly flattened wood surfaces. Have you ever wondered why your jointer misbehaves? Let’s unravel this woodworking mystery together.

Importance of Flat Wood Surfaces

Flat wood surfaces hold significant importance in woodworking projects for the following reasons:

  • Stability: Flat surfaces provide strength and structural integrity to woodworking projects, ensuring proper fitting and preventing warping or distortion over time.
  • Precision: Flat surfaces are reliable reference points for accurate measurements, layout, precise cuts, joinery, and assembly, producing a professional and well-finished product.
  • Aesthetics: Smooth and flat wood surfaces enhance the visual appeal of the final piece, allowing for even staining, finishing, or painting and contributing to the overall beauty of the project.

Common Challenges with Jointers

Jointers, while valuable tools for achieving flat wood surfaces, can encounter common problems, including:

  • Uneven or Concave Surfaces: Improper setup or techniques can lead to jointers producing uneven or concave surfaces, which can cause gaps or misalignment when joining boards together.
  • Tearout: Dull blades, improper feed direction, or challenging grain patterns can result in tearout, where the wood grain tears or splinters during the jointing process.
  • Snipe: Improper support or misalignment of the tables can cause snipe, which refers to an undesired reduction in thickness or unevenness at the beginning or end of a board when passing it through the jointer.
  • Inaccurate Fence Alignment: When the jointer’s fence is not aligned correctly, it can lead to angled cuts or uneven edges, affecting the flatness of the wood surface.
  • Dust and Debris Buildup: Over time, jointers can accumulate dust and debris, hindering their performance and compromising the final surface’s quality.

Understanding Jointers

A jointer is a woodworking tool designed to create flat, smooth edges on boards. Its primary function is to straighten and square the edges in preparation for joining them together.

Types of Jointers

  • Benchtop Jointer: A compact and portable jointer is designed to sit on a workbench. It is suitable for more minor to medium-sized woodworking projects.
  • Floor-standing Jointer: Designed to handle larger workpieces, providing increased stability and durability, it is ideal for professional woodworking applications. Professional woodworking shops commonly have it and use it for large-scale projects.

How Jointers Work

  • Fence and Infeed Table: A jointer consists of an adjustable fence and an infeed table. The fence guides the board to maintain a straight edge during jointing. The infeed table supports the board fed into the cutting area.
  • Cutter Head and Blades: The cutter head, equipped with sharp blades, is the central component of a jointer. As the board passes over the infeed table and along the fence, the rotating cutter head removes a thin layer of wood from the edge, resulting in a flat and smooth surface.
  • Outfeed Table: After being cut by the blades, the board rests on the outfeed table. The outfeed table is aligned with the cutter head to ensure consistent thickness and flatness across the entire length of the board.
  • Adjustment Mechanisms: Jointers feature various adjustment mechanisms to control the depth of cut and align the fence and tables. These adjustments allow for precise and accurate results.

The Importance of Flatness

Precision in Woodworking

Flatness holds excellent importance in woodworking due to its impact on precision and accuracy in various aspects:

Joinery: Flat surfaces ensure precise and secure joinery, allowing components to fit together seamlessly and create strong connections in furniture and other woodworking projects.

Measurements and Layout: Flat surfaces are reliable reference points for accurate measurements, enabling precise cuts and proper assembly. It contributes to the overall quality and professional finish of the project.

Alignment: Flatness is crucial for aligning components such as table legs or cabinet doors, ensuring proper fit, and eliminating gaps or misalignments affecting functionality and aesthetics.

Safety Considerations

Maintaining flat wood surfaces is essential for ensuring a safe working environment in woodworking.

Stability: Flat surfaces provide stability and prevent furniture or wooden structures from wobbling or becoming unstable. It promotes user safety and minimizes the risk of accidents.

Tool Performance: Uneven surfaces can adversely affect performance, leading to unpredictable behaviour and potential safety hazards. Flatness ensures consistent tool operation and control, reducing the risk of accidents.

Aesthetic Appeal

The significance of flatness extends to the visual appeal of woodworking projects:

Finishing: Smooth and flat surfaces allow for even application of finishes, such as stains or paints. It enhances the overall appearance, creating a visually pleasing and professional-looking result.

Craftsmanship: Flatness reflects the attention to detail and craftsmanship in woodworking. It showcases the skill and dedication of the woodworker, enhancing the aesthetic value and overall impression of the piece.

Identifying the Issue

Initial Evaluation

Conducting an initial inspection is crucial to identifying potential problems with a jointer. It involves visually examining the jointer for any visible issues, such as damaged components, loose connections, or signs of excessive wear.

Common Indications of a Malfunctioning Jointer

Several common symptoms suggest a jointer may be experiencing issues:

  • Uneven Surfaces: A malfunctioning jointer may produce uneven surfaces on the boards, resulting in variations in thickness or irregularities along the edges.
  • Tear-out: When the jointer is not functioning correctly, it can cause tear-out, characterized by wood grain tearing or splintering during cutting. It can occur due to dull blades, improper feed direction, or challenging grain patterns.
  • Misaligned Boards: If the jointer consistently produces misaligned boards with gaps or irregularities when joined together, it indicates a problem with the jointer’s ability to align or level the edges properly.

Maintenance and Setup

Ensuring Optimal Jointer Performance

Following proper maintenance practices is essential for maintaining the jointer’s performance and prolonging its lifespan.

  • Lubrication: Regularly lubricate the jointer’s moving parts to minimize friction and ensure smooth operation.
  • Blade Maintenance: Inspect and sharpen the blades regularly to maintain their cutting effectiveness. Replace any worn or damaged blades.
  • Cleaning: Thoroughly clean the jointer, including its surfaces, tables, and fences, to prevent the buildup of dust, debris, or residue that can hinder performance.

Proper Jointer Setup

Achieving accurate and flat surfaces with a jointer relies on proper setup techniques:

  • Blade Alignment: Ensure that you correctly align the jointer’s blades with each other and parallel to the tables. It guarantees consistent and even cutting across the entire surface. 
  • Infeed and Outfeed Table Adjustment: Adjust the height and level of the infeed and outfeed tables to facilitate a smooth and continuous feed of boards through the jointer. 
  • Fence Alignment: Verify and adjust the jointer’s fence to ensure it is perpendicular to the tables, enabling precise and straight edges during the jointing process.

Common Problems and Solutions

Blade Dullness

Indications of Dull Blades: Signs of dull blades in a jointer include rough or inconsistent cuts, increased tear-out, and reduced cutting efficiency. Wood may exhibit signs of burning or excessive friction.

Blade Replacement and Sharpening: To address dull blades, consider replacing them with new ones or sharpening the existing edges. Follow manufacturer guidelines or seek professional assistance for proper blade replacement or sharpening techniques.


Causes of Snipe: Snipe occurs when a jointer produces a deeper cut or indentation at the beginning or end of a board. It can result from improper technique, misaligned tables, or insufficient support during the feeding process.

Prevention and Correction of Snipe: Ensure adequate support for the workpiece at the jointer’s infeed and outfeed ends to prevent snipe. Apply consistent and steady pressure throughout the feeding process. Adjust the infeed and outfeed tables and address misalignment issues to minimize or eliminate snipes.

Uneven Pressure on the Infeed Table

Signs of Uneven Pressure: Uneven pressure on the infeed table can lead to inconsistent cuts, resulting in variations in thickness or irregularities in jointed edges. The wood may need to feed smoothly through the jointer, making it challenging to achieve flat surfaces.

Resolving the Issue: To correct uneven pressure, ensure proper support and guidance for the workpiece during the feeding process. Adjust pressure mechanisms or feed rollers to achieve an even pressure distribution. Regularly inspect for misalignment or mechanical issues causing the uneven pressure and make necessary adjustments or repairs.

Material Selection

Selecting Appropriate Wood: Choosing the appropriate wood for a project is crucial for the desired outcomes. Consider factors such as durability, stability, grain pattern, and the intended purpose of the finished piece. Different wood species have unique characteristics that influence jointing ease and overall quality.

Addressing Problematic Wood Grain: Some wood grains, such as interlocking or highly figured patterns, can present challenges during jointing. Pay attention to grain direction and adjust the feed direction to address these issues. Reducing cutting depths or making multiple passes can minimize tear-out and achieve smoother surfaces.

Managing Thickness Variations in Wood: Natural variations in wood thickness can impact the jointing process. When working with wood of varying thicknesses, ensure proper support and alignment to maintain consistent contact with the jointer’s tables. Use shims or additional support to level out significant variations and achieve even thickness throughout the board.

Techniques for Achieving Flat Surfaces

Fundamental Flattening Technique: The basic technique for achieving flat surfaces involves using a jointer to pass a board’s face or edge over the cutter head. Standard flattening tasks commonly utilize this process to achieve a smooth and level surface.

Advanced Techniques for Challenging Projects:

Face Jointing: Face jointing is a technique used to flatten the broader face of a board. It involves making multiple passes over the jointer, applying even pressure, and ensuring consistent contact between the board and the jointer’s tables. This technique is beneficial for boards with significant warping or cupping.

Edge Jointing: Edge jointing creates straight and square edges on boards. By guiding the board along the jointer’s fence, operators can remove any irregularities, resulting in a smooth, straight edge. This technique is essential for achieving precise edges for joinery and panel glue-ups.

Safety Measures

Personal Protective Equipment: Prioritize safety by wearing suitable personal protective equipment (PPE), such as safety glasses, ear protection, and a dust mask. These items protect against potential hazards.

Dust Collection and Cleanup: Implement effective dust collection systems to minimize airborne particles. Regularly clean the jointer and the surrounding area to maintain a clean and safe working environment.

Jointer-Specific Safety Tips: Follow specific safety guidelines for using a jointer, such as keeping hands clear of the cutter head, using push blocks or push sticks to maintain a safe distance from the blades, and ensuring the jointer is adequately grounded.

Alternative Tools and Methods

  • Hand Plane: Woodworkers can utilize hand planes to flatten and smooth wood surfaces. They offer control and precision, making them suitable for smaller projects or when working with delicate wood.
  • Router Sled: A router sledge, also known as a planing jig, can flatten large or oversized wood pieces. This method involves mounting a router onto a sledge and passing it over the workpiece to achieve a level surface.
  • Planer: Planers are commonly used for thicknessing boards but can also assist in flattening surfaces. They excel at removing significant amounts of material quickly and efficiently.
  • Determining When to Use Alternatives: Alternative tools and methods may be appropriate when access to a jointer is limited, when working with irregularly shaped or oversized pieces, or when different levels of precision or control are required.

Resolving Complex Issues

Addressing Severe Tear-out: Cutting depth and feed rate adjustments can help minimize the problem when confronted with severe tear-out during the jointing process. It is also crucial to use sharp blades and ensure proper grain orientation. If tear-out persists, experimenting with different cutting angles or employing alternative tools like hand planes may be necessary.

Managing Bowed or Twisted Boards: To flatten bowed or twisted boards, begin by face jointing to eliminate high spots. Then, alternate between face and edge jointing, gradually working on the board until it becomes flat. Additional techniques, such as clamping or caulking, may be required to apply pressure and encourage the board to straighten during jointing.

Coping with Excessively Wide Boards: Jointing extensive boards can pose challenges due to size. To address this, consider using additional support, such as roller stands or infeed/outfeed tables, to stabilize the jointing process. Take multiple passes, adjusting the cutting depth incrementally to ensure even material removal across the board’s width.

Maintenance Schedule

Regular Maintenance Checklist: Establish a regular maintenance routine for your jointer. It should include cleaning the machine after each use, checking and tightening all fasteners, inspecting the belts and pulleys, and lubricating moving parts as the manufacturer recommends.

Seasonal Checks: Conduct seasonal checks to ensure optimal performance and longevity of your jointer. It may involve inspecting the motor and electrical connections, checking the alignment of the tables, and verifying the accuracy of the fence and depth adjustments. Make any necessary adjustments or repairs to keep your jointer in top condition.


Recap of Key Points: In summary, this guide has provided techniques for resolving complex issues encountered during jointing, such as severe tear-out, bowed or twisted boards, and extensive panels. It also emphasized maintaining a maintenance schedule to ensure your jointer’s efficient and safe operation.

Importance of Routine Maintenance: Routine maintenance plays a vital role in maintaining the optimal performance of your jointer. By following a maintenance schedule, you can prevent issues, extend the lifespan of your machine, and achieve consistent and high-quality results in your woodworking projects.

FAQs (Frequently Asked Questions)

Why is my jointer leaving marks on the wood?

Dull blades, improper technique, or issues with the jointer setup can cause marks on the wood.

Can I use a jointer to flatten large slabs?

You can use a jointer to flatten large wood slabs with the right techniques:

  • Preparation: Ensure your jointer fits the slab’s size, possibly with extra help for handling.
  • Initial Inspection: Check for twists, cupping, or warping, marking problem areas.
  • Setup: Level and align infeed and outfeed tables for an even surface.
  • Safety: Use safety gear and caution due to the slab’s size.
  • Multiple Passes: Flatten both sides with multiple passes, starting with the convex side down.
  • Proper Support: Prevent snipe and tipping with sufficient infeed and outfeed support.
  • Feeding Direction: Experiment with feed directions to minimize tear-out and snipe.
  • Check Progress: Periodically assess flatness with a straightedge, marking high spots.
  • Final Pass: Finish with a light-depth pass for a smooth surface.
  • Planer Finish: Consider using a planer or other tools for a smoother finish.

Flattening large slabs takes time, patience, and safety awareness, but it yields excellent results for your woodworking projects. Prioritize safety and quality for your desired outcomes.

How often should I replace jointer blades?

Replace jointer blades based on usage, wood type, maintenance, visible damage, and inconsistent cuts.

Usage Frequency: Heavy use wears blades faster; occasional use extends lifespan.

Wood Type: Hardwoods wear blades faster; exotics and figured woods are abrasive.

Maintenance: Regular sharpening and honing prolong blade life; neglect leads to earlier replacement.

Visible Damage: Chips, nicks, or dents signal replacement, ensuring surface quality and safety.

Inconsistent Cuts: Replace dull blades to maintain project quality.

Regularly inspect blades for optimal performance and safety. Some keep spare sets for minimal downtime. Base blade replacement on condition and project results.

Is it normal to have a little snipe on a jointer?

While snipe is common on jointers, understanding and addressing it effectively is crucial. Snipe occurs as a slightly deeper cut at a board’s beginning or end when passing through a jointer due to infeed and outfeed table setup and pressure.

To minimize snipe:

  • Setup: Ensure level, coplanar jointer tables for a consistent surface.
  • Pressure: Apply even pressure when feeding and exiting the board to reduce end snipe.
  • Extra Length: Start with longer boards than needed to trim off sniped portions.
  • Feed Direction: Experiment with forward and backward passes to find the least snipe-prone approach.
  • Featherboards: Use these to maintain downward pressure for reduced snipe.
  • Practice: Like woodworking skills, snipe reduction improves with practice.

Remember, some snipe may persist, but these techniques and setup adjustments can significantly minimize its impact on your woodworking projects.

What safety gear do I need when using a jointer?

When using a jointer, prioritize safety with the following gear:

  1. Safety Glasses: Protect your eyes from wood chips, debris, and dust. Use ANSI-rated glasses or goggles for ample protection.
  2. Ear Protection: Reduce noise-related risks with earmuffs or earplugs, especially due to the jointer’s loud operation.
  3. Dust Mask or Respirator: Maintain respiratory health using a mask or respirator with proper filtration for wood dust.
  4. Dust Collection System: Keep your workspace clean and minimize airborne dust by installing a dust collection system.
  5. Push Blocks: Ensure hand safety by using push blocks or pads to control workpieces and prevent contact with the jointer’s cutterhead.
  6. Closed-Toe Shoes: Protect your feet in the woodworking area by wearing closed-toe or steel-toed shoes.

Always follow your jointer’s user manual safety guidelines and consider additional measures based on your workspace and materials. Prioritize safety in your woodworking activities.

Can I join wood with knots or imperfections?

Joining wood with knots or imperfections in woodworking can be challenging due to the density variation. To achieve better results:

  • Assess Knots: Examine size, type, and location. Small knots may be manageable; large or loose ones pose challenges.
  • Sharp Tools: Ensure sharp jointer or planer blades for knot handling.
  • Feed Direction: Experiment with grain and against grain for the best approach.
  • Reduce Depth of Cut: Minimize tear-out by reducing depth when encountering knots.
  • Support: Use a sacrificial backer board for tear-out prevention.
  • Alternatives: Sometimes, repositioning or replacing the problematic section is more practical.

Practice and experience are key; test on scrap wood with similar issues before your project.

Are jointers suitable for beginners?

Beginners can use jointers, but proper training and safety knowledge are essential. Jointers create smooth, flat surfaces in woodworking but can be hazardous if mishandled. Start with simpler tools, progress as skills grow. Seek guidance from experienced woodworkers or take classes for safe, effective jointer use.

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