Bit-sal

This engine recreates Bit-sal, where the slats are tilted 45° and joined diagonally inside the frame. The name comes from bit, "slanted," after the way the slats are set at an angle — the diamond grid formed by those crossing slats is the face of this changho. You set only the horizontal cell count; the vertical count is calculated automatically so the cells stay perfectly square, and there is no separate setting for the angle.

Characteristics

• Cells are always fixed as squares, with slats laid along their diagonals to create the 45° pattern.
• You cannot set the vertical cell count. It is derived automatically from the square cell size determined by the horizontal cell count and slat width.
• Clipping keeps the slats from protruding outside the frame.

Door Tab — Main Parameters

Item	Description
Hinged · Sliding / panels	Hinged 1–2 panels, sliding 1–4, 6 or 8 panels
Frame width / height	Wall opening dimensions (width 100–10,000mm, height 400–5,000mm). The outer panel size is calculated with the frame thickness removed.
Horizontal cells	2–30. The number of square cells across — this and the slat width set the cell size, and the vertical count follows automatically.
Auto-fit frame height	When checked, the frame height is adjusted so the last row meets the bottom rail exactly
Left/right stile · top/bottom rail width	Outer frame width (mm)
Slat width	Width of each slat (mm). It also determines the cell size (one side of the square).
Use transom panel	Adds a transom panel zone at the top when checked

Specs Tab — Production Specification

Item	Description
Frame / outer / inner width and height	Automatically calculated measured dimensions
Horizontal / vertical ink lines	Spacing of the square cells, horizontally and vertically
Slat ink lines	Distance between diagonal intersections
Half-lap width	Calculated equal to the slat width
Vertical stile groove width / Horizontal stile groove width	Slat width × (1 + √2) — the width of the groove the 45° diagonal slats cut into the frame

Member List

Instead of horizontal and vertical slat groups, parts are listed as a diagonal slat group. Slats of equal length are bundled by each diagonal direction (↘ and ↗) and listed as length × quantity. Frame members, the transom panel (if used) and the door frame follow below. The surface area, weight & volume table further down works the same way as Se-sal — see the Se-sal guide for details.

Finish Tab

Choosing the wood, hardware and colors per part to colour (frame, stile & rail, slat, face) works the same as Se-sal. Pick Face as the part and you can click cells in the drawing to fill just those cells (Paint face color).

Example Uses

• Lattice patterns for hanok lantern screens (bangdeung)
• Contemporary interior screen partitions
• Railing patterns for traditional pavilions