Bench joinery
Panel in a grooved frame
- where
- panel width and height (mm)
- clear opening width (mm)
- groove depth (mm)
- total width clearance (mm)
- clear opening height (mm)
- total height clearance (mm)
Explain this equation
Sizes a loose panel that sits in grooves in a frame, such as a door or cabinet panel, allowing room for movement.
W and H are the clear opening sizes between the frame members, in millimetres. d is the groove depth. cw and ch are the total clearances across the width and height, covering both edges together. wp and hp are the panel sizes.
The panel reaches into a groove on each side, so it gains 2d across each dimension. The clearance is then taken off so the panel can expand and contract without splitting the frame.
A 500 × 700 mm opening with 10 mm grooves and 4 mm total clearance gives a 516 × 716 mm panel.
Watch out: the clearance is the total, not per edge. It must be less than 2d, otherwise the panel could drop out of a groove. The calculator checks this.
Add groove engagement and deduct the specified total movement clearance.
Enter your values to see the result.
Good to know
Clearance is total across each dimension, not per edge, and must be less than twice the groove depth. Assumes a centred panel with positive engagement in all four grooves; the design may require more engagement.
Sources
- Geometry / arithmetic
This is a calculation aid, not a structural design or compliance certificate. Every default is an example, not a specification for your project.