Scarf joint

A scarf joint lengthens a beam: both ends get the same angled plane with a square abutment, so they hook into each other.

Scarf joint. Drawn by the editor's own geometry code.

When to use it

Use it for purlins and wall plates that must be longer than your timber. The abutment lets the joint take tension and stops the halves sliding. Put the same joint, mirrored, on the other end.

Fields

Field	Unit	Range or options	Default	What it changes
End		Start, End	End
Position X	mm	from 0	3000	The end face the joint sits on.
Length	mm	from 1	300	How far the joint runs into the beam.
Inclination	°	1 to 89	33.7	Inclination of the scarf plane relative to the beam axis.
Lip length	mm	from 0	175	Length of the first plane, measured ALONG the slope, not horizontally.
Lip depth	mm	from 0	17	Depth of the abutment, square to the scarf plane.
Depth opposite side	mm	from 0	20	How deep the joint starts at the root, measured from the opposite side.
Drill holes		0 to 2	0	Number of dowels through the joint (0, 1 or 2).
Face		Top, Bottom, Front, Back	Bottom	The side of the part the processing is on.

Default: what Add fills in on a 3000 mm part of 120 x 120 mm.

Add a scarf joint

1. Select the part in the Parts list.
2. Under Extra processings, click Add.
3. Type scarf in the search field and pick Scarf joint.
4. Set Face, End and Position X.
5. Set Length, Inclination, the lip values and the number of Drill holes.
6. Check that the part shows a green check. If not, open the Issues tab.

Caution

Only the shape “baseside” is drawn, the only one in the official machine files. For “refside” and “classic” the zone stays dashed.

Machine export

Format	Status	Details
BTLx	Supported	ScarfJoint.
BVN (Hundegger)	Not written	Refused: the inclination mapping is missing.
BVX2 (Hundegger)	Not written	Refused: the inclination mapping is missing.

A file that the app writes is not a check by your machine. See Export for what each format is for.

Related pages

• Straight lap: The simplest lengthening joint: two ends cut away so they overlap, held by dowels. Fields, defaults and machine export.
• Scarf-joined purlin and wall plate: Two beams lengthened into an 8.8 m purlin with a keyed scarf joint, a wall plate joined with a simple scarf, and a cross tie with a dovetail end.
• Dovetail: The classic log building corner joint: a tapered tail that drops into the crossing beam. Fields, drawing accuracy and machine export.
• Housed joint: The crossing joint of a log cabin: each beam bites into the other. Eight dimensions, a dashed drawing and machine export.
• Arch: Machine a true circular arc into a face over part of the length: concave or convex. Centre, chord, camber and machine export.
• Tyrolean: The flat Tyrolean dovetail for log building corners: one angled plane per side. Fields, drawing limits and machine export.