How do you calculate rail length for a 5-piece Shaker door?

The rail length formula is: Rail Length = Finished Door Width - (2 × Stile Width) + (2 × Tongue/Tenon Length). For stub-tenon router bits with a 3/8" (9.5mm) groove and tenon, you subtract 2 stile widths and add back 2 tenon lengths.

What is a Spaceball allowance in cabinet door panels?

Solid wood and plywood panels expand and contract with humidity changes. Woodworkers insert rubber Spaceballs (or leave a 1/16" gap per side = 1/8" total deduction in width and height) so the center panel can move freely without busting the cope-and-stick rail joints or rattling.

Why is the bottom rail on Shaker doors often wider than the top rail?

To provide optical balance. When doors are viewed from standing eye level, equal width top and bottom rails make the door look top-heavy. Cabinetmakers commonly use 2-1/2" stiles and top rail paired with a 3" or 3-1/2" bottom rail.

JigFoundry Workshop Cut Sheet

Project: 5-Piece Shaker Cabinet Door Calculator (Overlay & Inset Cut List) | Generated: Oct 14, 2026, 10:50 PM

JIGFOUNDRY.COM

Physical Shop Engine

Rule: Measure twice, check kerf allowance (1/8"), confirm actual sheet thickness before ripping. Checkboxes [ ] indicate cut verification.

5-Piece Shaker Cabinet Door Calculator

Cope-and-stick stub tenon, pocket screw butt joints, spaceball expansion gaps, and single or paired double door batches.

Active Unit:

Dual-Scale Display: All parts show primary units plus secondary reference.

1. Opening & Config

Door Mount

Opening Width18"

Opening Height30"

Door Setup

Mounting Style

Perimeter Overlay (mm)

2. Stiles & Rails

Frame Proportions

Stile Width2 1/2"

Top Rail Width2 1/2"

Bottom Rail WidthTraditional wider bottom

Frame Stile/Rail ThicknessActual: 19.05 mm (0.750")

ANSI A208.2 MDF Standards (Standard Calibrated Core)

Add Mid-Rail (Split Pantry Door)

3. Joinery & Spaceball

Panel Tolerances

Rail Joinery Method

Cope & Stick / Stub TenonRail length includes 2x tongue/tenons into stiles.

Pocket Screw / Dowel Butt JointRails cut square between stiles (zero tongue).

Groove Depth (mm)

Spaceball Gap/Side

Center Panel ThicknessActual: 6.35 mm (0.250")

True 1/4" Calibrated MDF or 6mm Baltic Birch

Assembled & Exploded Shaker Door Diagram

Finished Size: 482.6 x 787.4mm

Master Cut List is Empty

Configure drawer dimensions, Shaker doors, or cabinet carcasses above, then click "Add to Cut List" to build your workshop project.

Shaker Door Construction Formulas & Spaceball Allowances

Cope & Stick Stub-Tenon Invariant

When milling rails on a shaper or router table, each rail end receives a coped tongue that enters the groove of the vertical stile:

Rail Cut Length = Door Width - (2 × Stile Width) + (2 × Tongue Length)

For pocket-screw butt joints or domino construction, tongue length is zero.

Center Panel Expansion Gap

The center panel rests inside grooves milled into the inside edges of all 4 frame members:

Panel Width = Door Width - 2(Stile) + 2(Groove Depth) - 2(Spaceball Gap)

A 1/16" (1.6mm) clearance per side prevents glue squeeze-out from pinning the panel and cracking during winter shrinkage.