Creating rock-solid mortise and tenon joints is a key woodworking skill—and it all starts with getting the mortise right. While tenons can be fine-tuned for a snug fit, mortises demand accuracy from the very beginning. That’s where a hollow chisel mortising machine comes in.
When properly set up, a mortising machine delivers clean, precise mortises with minimal cleanup. In this video, we’ll walk you through the essential setup tips and cutting techniques to get professional-quality results every time.
Step 1: Marking Out the Mortise
Accurate layout is the foundation of a good mortise. Instead of relying on stops, mark each mortise location individually. Use a marking gauge to define the sides of the mortise from both edges of your workpiece—this ensures the mortise is centered and guides your fence setup later.
Step 2: Tool Setup Basics
Installing the chisel and bit correctly is crucial. Let the bit do most of the cutting work to reduce heat buildup and avoid clogging. Adjust the bit slightly lower than the chisel to help eject chips more efficiently and extend tool life.
Step 3: Cutting the Mortise
The order of cuts matters. To avoid deflection and ensure straight, accurate mortises, follow an alternating hole pattern. This keeps the bit supported on multiple sides as you work down the length of the mortise.
Apply a dry spray lubricant to reduce friction and help remove chips. If you're cutting several mortises, pause periodically to let your chisel and bit cool down.
After the initial cuts, make a few cleanup passes to remove any ridges or compacted chips left behind. The result? A smooth, well-sized mortise ready for a tight-fitting tenon and a rock-solid joint.
If you are looking to upgrade your mortising machine look no further than this precision X-Y sliding table jig for accurate, repeatable mortises every time. Designed to simplify the tedious task of repositioning your workpiece, this shop-built accessory features front-to-back and side-to-side movement controlled by hand wheels—perfect for drilling clean, consistent mortises quickly and easily.
The jig is built around a solid base, a floating carriage, and a sliding top platform, which glide smoothly using Acme-threaded rods, steel guide rods, and bronze bushings. A heavy-duty hold-down and toggle clamp secure your workpiece in place while you fine-tune the cutting position with precision.
With simple construction, affordable hardware, and easy-to-follow steps, this jig is a must-have upgrade for any serious woodworker using a hollow-chisel mortiser.
