OFFSET

CompleteChecked against Musa CAD 0.8.0Verified Oct 23, 2026

Create a parallel copy of a curve at a specified distance.

Type: OFFSET or O
On the ribbon: Home › Modify › Offset
Since: Musa CAD 0.1.0

What it asks first

Command: OFFSET
Current settings: Erase source=No  Layer=Source  OFFSETGAPTYPE=0
Specify offset distance or [Through/Erase/Layer] <Through>:

Read from Musa CAD 0.8.0 itself (musacad --dump-wiki-data), so these facts always match the release this wiki is built for (0.8.0).

OFFSET makes a copy of an object that runs alongside it at a fixed distance. Use it for wall thicknesses, borders, rings and any shape that must stay the same distance from another.

How it works

Type O and press Enter. Musa CAD shows the current settings and asks for the distance. Type it, then pick the object to copy and click on the side where the copy should go. Musa CAD asks for the next object, so you can offset several in a row. Press Enter when you are done.

Command: O
Current settings: Erase source=No  Layer=Source  OFFSETGAPTYPE=0
Specify offset distance or [Through/Erase/Layer] <Through>: 6
Select object to offset or [Exit/Undo] <Exit>: (pick the shape)
Specify point on side to offset or [Exit/Multiple/Undo] <Exit>: (click outside it)
Offset created.
Select object to offset or [Exit/Undo] <Exit>: (pick the circle)
Specify point on side to offset or [Exit/Multiple/Undo] <Exit>: (click inside it)
Offset created.
Select object to offset or [Exit/Undo] <Exit>: Enter

On the left, an L-shaped closed polyline in black with a blue copy 6 units outside it; a click mark sits outside the shape. On the right, a black circle with a smaller blue circle 6 units inside it; the click mark is inside the circle. — One distance, two objects: the click decides the side.

Before you click the side, the copy is drawn under the cursor, so you can see where it will go.

Instead of typing the distance, you can click two points. Musa CAD then asks Specify second point: and uses the distance between them.

Options

Option	What it does
Through (`T`)	No fixed distance. After you pick the object, click a point and the copy passes through it. The side prompt becomes `Specify through point or [Exit/Multiple/Undo] <Exit>:`.
Erase (`E`)	At the distance prompt. Asks `Erase source object after offsetting? [Yes/No] <No>:`. With Yes, the original is deleted once the copy is made.
Layer (`L`)	Asks `Enter layer option for offset objects [Current/Source] <Source>:`. Source puts the copy on the original’s layer, Current on the current layer.
Exit (`E`)	At the object and side prompts. Ends OFFSET, the same as `Enter`.
Multiple (`M`)	Keep clicking to make more copies. Each new copy steps out from the one just made, so you get evenly spaced rings or lines. Press `Enter` to go back to picking an object.
Undo (`U`)	Removes the last copy. Each Undo removes one more.
`Enter` at the distance prompt	Keeps the distance shown in `<>`, or Through.

Settings OFFSET remembers

The distance (or Through), Erase and Layer are kept for the next time you use OFFSET, for as long as Musa CAD stays open. The first line of each run shows Erase and Layer, and the distance prompt offers the last distance in <>.

The same line shows OFFSETGAPTYPE. It decides what fills a polyline’s outside corners when the copy pulls its straight segments apart: 0 carries the segments on until they meet (a sharp corner), 1 puts an arc there, and 2 cuts the corner with a bevel. Type OFFSETGAPTYPE to change it. See OFFSETGAPTYPE.

Good to know

Lines, arcs, circles, polylines, construction lines and rays can be offset. An ellipse or a spline gives a spline. Anything else says Offset: can't offset that entity.
The copy has the original’s layer, colour, linetype, lineweight and linetype scale. With Layer set to Current, it goes on the current layer instead.
A distance of 0 or less is refused with Value must be positive and nonzero.
An inward copy that would shrink to nothing is refused. A circle or arc says Offset distance too large (would collapse the curve)., a polyline says Offset distance too large for this polyline., and an ellipse or spline says Offset distance too large for this curve (the offset would cross itself).
With Through, a point right on the object is refused with Offset: the through point lies on the object.
Each copy is its own undo step, both inside OFFSET and with U afterwards.
To offset an outline drawn as separate lines in one go, first join them into one polyline with JOIN.

Compared with AutoCAD

OFFSET uses AutoCAD’s prompts and options: Through, Erase, Layer, and Multiple, where each copy steps out from the last. As in AutoCAD, an ellipse or a spline offsets to a spline.

Join separate lines into one polyline first with JOIN.
Round the corners of the new outline with FILLET.
See all the editing commands together in Modifying objects.

Reading settings