Izzy Swan from izzy swan demonstrated the test featured in this video.
This video shows a homemade horizontal slot mortiser built from scrap plywood and an inexpensive trim router, designed to replicate and expand on the functionality of a Festool Domino at a fraction of the cost.
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Design and Purpose
The build is intended to perform horizontal slot mortising and additional joinery tasks without the high price tag of a dedicated machine.
Izzy focused on creating a versatile, low-cost platform that can make mortises, dowel holes, and elongated slots, while remaining easy to service and adapt over time.
Construction and Materials
The core structure uses plywood dovetail slides for linear motion rather than expensive metal rails, demonstrating a practical shop-made approach to motion control.
Components are largely shop scraps plus a trim router and hardware, keeping the total build cost well under what a commercial machine would cost.
Motion System: Plywood Dovetail Slides
Plywood dovetail slides proved surprisingly effective, providing smooth travel and simple maintenance if tightening or adjustment is needed later on.
Izzy notes that sawdust buildup was not a significant problem and that the slides can be re-tightened by shifting screw positions, which adds longevity to the design.
Router, Bits, and Cutting Strategy
The setup uses a trim router and affordable straight bits rather than large spiral cutters, prioritizing accessibility and replaceability of cutters.
Longer straight bits enable deeper mortises and step-through grooves, and although passes must be conservative, these bits are sharpenable and available in many sizes for varied joinery needs.
Alignment, Stops, and Accuracy
Alignment is achieved by locking start and stop positions on the carriage and lowering the router to engage the work, which produces repeatable mortises when matched tenons are prepared accordingly.
Izzy allowed a small amount of play in layout to ensure parts fit together cleanly, and the method delivered accurate joinery in testing.
Accessories and Additional Uses
Simple match-fit fixtures, toggle clamps, and a few shop-made accessories expand functionality for doweling, pass-through slots, and repeated layouts.
Shop-made dowels with relief grooves were used to ensure glue squeeze-out and improve glue surface, showing how small accessories can improve joint reliability.
Performance, Limitations, and Upgradability
The machine excels as a stationary shop tool that delivers professional-style results for a small fraction of the price of a dedicated commercial unit.
Limitations include a lack of dust collection and portability, but the design is intentionally open-ended so future upgrades (added dust control, refined slides, or alternate fixturing) are possible.
Cost and Practical Value
By using common materials and an economy router, the build demonstrates significant cost savings while retaining useful capabilities for joinery work.
For hobbyists or small shops, this approach offers a pragmatic trade-off: lower upfront cost and customizability in exchange for sacrificing portability and integrated dust management.
Overall Takeaways
This homemade slot mortiser illustrates how thoughtful design and basic shop skills can deliver a versatile tool that solves real workshop needs without expensive proprietary hardware.
Izzy’s approach is useful for woodworkers who want to experiment, tailor a tool to their workflow, and expand functionality beyond a single-purpose commercial device.
Conclusion
The project is a strong example of practical problem solving in the shop: it recreates core Domino functions, adds extra capability like doweling and elongated slots, and keeps the build accessible and serviceable.
Please support Izzy by visiting his website: https://www.izzyswan.com/.