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How-to

From 2D to 3D in AutoCAD

How to turn a 2D drawing into a 3D solid in AutoCAD: extrude, press pull and revolve a closed profile, add and subtract. Free online 3D solids, still partial.

In AutoCAD a solid usually starts as a 2D drawing: a closed profile, drawn as any plan is, then extruded to a height or turned round an axis, and joined to other solids or cut by them. MellowCAD's 3D solids are made the same way, with the same commands. They are still partial: there are no sweeps, lofts, meshes or rendering yet. Each section shows a session the engine draws, its history as you would type it.

Draw a closed profile

A solid needs a closed profile: a closed polyline, a rectangle, a circle or a region. Lines that meet end to end are still separate objects: JOIN makes one polyline of them, or REGION a region. Draw the profile in plan, where typing its points is easiest.

Extrude it

EXTRUDE: pick the profile, press Enter and type the height. Seen from above, a solid looks just like its profile: turn the view with VIEW or the ViewCube to see it, and choose how it is drawn with VSCURRENT.

An L profile as one closed polyline, extruded 30, seen from the south-east.
  1. Command: PLINE
  2. Specify start point: 0,0
  3. Current line-width is 0.00
  4. Specify next point or [Arc/Halfwidth/Length/Undo/Width]: @80,0
  5. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @0,15
  6. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @-60,0
  7. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @0,45
  8. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: @-20,0
  9. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: C
  10. Command: EXTRUDE
  11. Current wire frame density: ISOLINES=4, Closed profiles creation mode = Solid
  12. Select objects to extrude or [MOde]: 1 found
  13. Select objects to extrude or [MOde]:
  14. Specify height of extrusion or [Direction/Path/Taper angle/Expression]: 30
  15. Command: -VIEW
  16. Enter an option [Orthographic]: SEI
  17. Regenerating model.
  18. Command: VSCURRENT
  19. Enter an option [2dwireframe/Hidden/Conceptual] <2dwireframe>: H
  20. Command: ZOOM
  21. Specify corner of window, enter a scale factor (nX or nXP), or [All/Extents/Previous/Scale/Window/Object]: E
  22. Command: ZOOM
  23. Specify corner of window, enter a scale factor (nX or nXP), or [All/Extents/Previous/Scale/Window/Object]: 0.8x
An L profile as one closed polyline, extruded 30, seen from the south-east.

Press and pull an area

PRESSPULL needs no profile: click inside any closed area, even one bounded by separate lines, and type the height. Clicked on a solid's face, it pushes or pulls that face.

A closed area, pressed and pulled from inside: it becomes a solid.
  1. Command: PRESSPULL
  2. Select object or bounded area:
  3. 2 loops extracted.
  4. 1 Region created.
  5. Specify extrusion height or [Multiple]: -8
  6. 1 extrusion(s) created
  7. Select object or bounded area:
  8. Command: -VIEW
  9. Enter an option [Orthographic]: SEI
  10. Command: ZOOM
  11. Specify corner of window, enter a scale factor (nX or nXP), or [All/Extents/Previous/Scale/Window/Object]: 0.8x
A closed area, pressed and pulled from inside: it becomes a solid.

Revolve it

REVOLVE turns a profile round an axis: pick the profile, give the axis by two points, an object or the X, Y or Z axis, then the angle, a whole turn by default.

A half section revolved round the Y axis.
  1. Command: REVOLVE
  2. Current wire frame density: ISOLINES=4, Closed profiles creation mode = Solid
  3. Select objects to revolve or [MOde]: 1 found
  4. Select objects to revolve or [MOde]:
  5. Specify axis start point or define axis by [Object/X/Y/Z] <Object>: Y
  6. Specify angle of revolution or [STart angle/Reverse/EXpression] <360>:
  7. Command: -VIEW
  8. Enter an option [Orthographic]: SEI
  9. Command: ZOOM
  10. Specify corner of window, enter a scale factor (nX or nXP), or [All/Extents/Previous/Scale/Window/Object]: 0.8x
A half section revolved round the Y axis.

Add and subtract solids

UNION makes one solid of several, SUBTRACT takes one or more away from another, and INTERSECT keeps what they share. A hole is a cylinder subtracted from the solid it goes through.

A cylinder subtracted from a box: a hole through it.
  1. Command: SUBTRACT
  2. Select solids, surfaces, and regions to subtract from ..
  3. Select objects: 1 found
  4. Select objects:
  5. Select solids, surfaces, and regions to subtract ..
  6. Select objects: 1 found
  7. Select objects:
A cylinder subtracted from a box: a hole through it.

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