Best Construction Methods for Flat Packs: 

When it comes to flat pack cabinetry, the joinery method you choose doesn’t just influence the final product—it has a direct impact on your CNC runtime, tool wear, labour requirements, and ultimately your cost of goods sold (COGS). For manufacturers selling cut-to-size cabinetry (AKA flat packs), selecting the right construction method is a balancing act between efficiency, strength, ease of assembly, and customer satisfaction.

In this article, we take a detailed look at four of the most common flat pack construction techniques—butt and screw, mortise and tenon, dowel, and confirmat screw—exploring their advantages, disadvantages, and best use cases.

Overview: This is the most basic form of cabinet construction. It involves simply butting one panel against another at a right angle and securing them with screws. There’s no special shaping or alignment features—just put them together and punch in a screw.

Pros:

• Fastest CNC processing: Because there’s no need for complex toolpaths, extra machining, or secondary processes, this is the quickest method to produce on a CNC machine. It’s ideal for fast turnarounds.
• Minimal tool wear: Simple straight cuts and hole drilling mean your router bits and tools experience less wear, extending their lifespan and reducing tooling costs.
• Low setup requirements: Great for shops that want to move volume quickly without investing in extra equipment.

Cons:

• High assembly error risk: Without alignment features, it’s easy for the person assembling the cabinet to misalign panels. This can result in boxes that aren’t square, reduced strength, or screws bursting through the panel edges.
• Low structural strength: This method relies solely on the screw’s holding power in MDF or particleboard, which is not always reliable, especially over time or with heavy loads. At a minimum, it’s advisable to additionally glue components before screwing, or pin them with a nail gun.
• Aesthetics and perception: Exposed screw heads can reduce the perceived quality of the finished product unless additional steps are taken to hide or plug them.

Best For: flat pack ranges where speed, price and ‘no frills’ are perhaps more important than longevity or finish quality.

Overview: A traditional woodworking joint, mortise and tenon involves inserting a protruding “tenon” on one piece into a matching “mortise” cavity on another. While incredibly strong and refined, it demands precise CNC routing and attention to material thickness.

Pros:

• Exceptional strength: The tenon provides a mechanical interlock, giving the joint significant holding power. It’s ideal for load-bearing components or cabinetry expected to last decades.
• Professional appearance: The joint is internal, with fewer required screws or fasteners. This gives a clean, high-end look.

Cons:

• Time-intensive CNC operations: This method significantly increases CNC machining time. Each joint requires multiple toolpaths and careful cutting, often at slower speeds to ensure clean finishes.
• Increased tool wear: More intricate cutting leads to greater wear and tear on your router bits and machinery, increasing maintenance costs.
• Material inconsistency issues: MDF and particleboard can vary in thickness between batches. Even a 0.2mm difference can affect the snugness of the fit, leading to loose joints or gaps—requiring frequent updates to software and machine settings.

Best For: Premium, showroom-quality cabinetry where strength, precision, and aesthetics justify the higher cost and longer production time.