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Manual / Dimension & Annotation

CENTERMARK and CENTERLINE

Draw a centre mark (CENTERMARK) on circles and arcs, and a centreline (CENTERLINE) between two lines.

What it does

  • CENTERMARK – draws a cross in the CENTER linetype at the centre of the selected circles or arcs.
  • CENTERLINE – draws a CENTER line midway between two lines. For parallel lines you get the middle line. For lines that converge you get the angle bisector.

Where to find it

  • Ribbon: Annotate › Dimensions › Center Mark / Centerline or Draw (Center Mark submenu)
  • Command line: CENTERMARK (aliases DIMCENTER, DCE)
  • Command line: CENTERLINE (alias CL)

Steps

  1. Select the circles (for example with QSELECT circle).
  2. Type CENTERMARK and press Enter (or CENTERMARK 5 to set the arm length to 5).
  3. For CENTERLINE: select two lines, then type CL.

CENTERMARK on every hole and CENTERLINE between the two lower lines
CENTERMARK on every hole and CENTERLINE between the two lower lines

Option Meaning
CENTERMARK [size] The arm length. If you omit it, 25% of the radius is used.

Try it: DN50 pipe flange

A standard DN50 pipe flange: Ø165 outside, Ø60 bore and four Ø18 bolt holes on a 125 mm pitch circle, in a front view and a side view. Two commands add every centre line.

  1. Front view: C 0,0 radius 82.5, then C 0,0 radius 30 for the bore.
  2. One bolt hole: C 44.19,44.19 radius 9. Select it, type ARRAYPOLAR 4 and click 0,0 as the centre.
  3. Side view: REC 120,-82.5 → 18 Tab 165 (flange), REC 138,-45 → 30 Tab 90 (hub), then the two bore lines L 120,-30 → 168,-30 and L 120,30 → 168,30.
  4. Select the six circles of the front view and type CENTERMARK 6. Every hole and the bore get a 6 mm centre cross.
  5. Select the two bore lines and type CL. A CENTER line appears midway between them: the axis of the flange.

DN50 flange with centre marks on every hole and the axis in the side view
DN50 flange with centre marks on every hole and the axis in the side view

Challenge: Undo step 4 and run CENTERMARK with no number. The arms become 25% of each radius, so the bolt holes get 2.25 mm arms and the bore 7.5 mm.

See also