How to Cut a Blind Mortice with a Chisel | Step 7 of 55
Part of the 55 Cuts & Joints for Beginners series.
In this lesson, we’re introducing the blind mortice — a key step towards one of the most important joints in carpentry: the mortise and tenon.
This is a practical skill you’ll use in real-world work, from fitting locks to building strong timber joints.
🎯 Aim of the Lesson
To learn how to mark out and cut a blind mortice accurately using a chisel.
📚 What You’ll Learn
- What a blind mortice is and where it’s used
- How to mark out using a combination marking gauge
- How to control depth safely and accurately
- The difference between a bevel edge chisel and a mortise chisel
- How to avoid splitting and damaging the timber
🧰 Tools & Resources
🔧 Tools, PPE, and materials used in this lesson:
- Combination marking gauge
- Bevel edge chisel
- Mortise chisel (optional)
- Mallet
- Vice or clamps
- Measuring tools (rule / square)
- Timber (practice piece)
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📏 Step-by-Step Process
- Mark out the mortice
Measure and mark the length (e.g. 60mm) and position on the timber. - Set your marking gauge
Adjust to the width of your chisel (e.g. 10mm or 12mm). - Mark the mortice lines
Run the marking gauge along the timber to create parallel lines. - Mark the depth
Use tape on your chisel to indicate the required depth (e.g. 25mm). - Secure the timber
Clamp firmly to prevent movement while cutting. - Start cutting away from the edge
Begin around 8–10mm from the end to avoid splitting. - Work in small steps
Cut every 2–5mm along the mortice to break up the fibres. - Remove waste carefully
Lever gently — avoid twisting side to side. - Keep the chisel square
Maintain 90° for clean, straight sides. - Clean and refine
Work back to your lines and tidy the bottom.
🧠 Key Learning Points
- A blind mortice does not go all the way through the timber
- You can complete this task with a bevel edge chisel if needed
- Mortise chisels give cleaner, straighter results
- Cutting in small steps prevents splitting
- Good marking out leads to better results
❓ Quick Quiz
- What is a blind mortice?
- Which chisel gives cleaner results — bevel edge or mortise chisel?
- Why should you cut in small steps?
👉 (Add your YouTube or Google Form quiz here)
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Next Lesson: Continue with Step 8 in the 55 Cuts & Joints series.