BALLOONTAG places a numbered balloon on a leader — the round or hexagonal callout used to key a part on an assembly drawing to a line on the parts list, or a detail on a sheet to the detail that draws it.
What BalloonTag does
The balloon can be divided into one, two, three or four compartments, which is how detail keys are normally written: detail number over sheet number, or a four-way split carrying item, quantity, detail and sheet.
It auto-increments. When the text you type is a whole number, the next balloon offers the number after it as its default. Ballooning twenty parts in sequence is then pick, pick, Enter — twenty times.
The command repeats until you press Enter.
How to use it
- Load the routine with
APPLOAD, or put it on your support file search path. - Type
BALLOONTAG. - Pick the arrow point — what the balloon is pointing at.
- Pick the balloon centre.
- Type the text, or press Enter to accept the next number.
- Keep going. Press Enter at the arrow prompt to finish.
How it works
The leader stops at the balloon’s edge rather than running under it, worked out by stepping back one radius along the leader angle from the centre. A leader that disappears beneath the balloon looks fine on screen and shows as a smudge on the plot.
The arrowhead is sized from DIMASZ × DIMSCALE, so it matches the arrowheads on the drawing’s dimensions without anyone having to remember what the scale is.
Divider lines are drawn as true chords of the circle, not as lines across a bounding box — so a two-way split meets the balloon edge exactly, at both ends, at any size.
Text is placed middle-centre in each compartment, so it is genuinely centred rather than approximately centred by nudging a baseline. On a four-way split that difference is visible.
Size. The balloon radius is DIMSCALE × 0.1563, a shade under a 5/16 inch diameter balloon on the plotted sheet, unless you override it — in which case your size is remembered for the rest of the session. Everything else is proportional to that radius, so the whole callout scales together.
Notes and limits
- Auto-increment only fires on whole numbers. Type
A1and the next balloon starts empty. - The size override lasts the session, not the drawing.
- Set DIMSCALE before you start. Everything is derived from it, so a wrong scale produces a consistently wrong callout.
- One undo group per balloon, so a misplaced one costs one
U.
Download and details
| Name | BalloonTag — place numbered detail balloons on leaders |
| Download | BalloonTag.lsp — 13.7 KB, plain AutoLISP source. Downloads directly; no zip to unpack. |
| Type | AutoCAD AutoLISP routine |
| Command | BALLOONTAG |
| Requires | nothing beyond a CAD platform with AutoLISP. |
| Source size | 13.7 KB, 327 lines |
| Error handling | Yes — a *error* handler restores every system variable it changed, on cancel as well as on error. |
| Undo | The whole operation is wrapped in a single undo group, so one U reverses all of it. |
| Compatibility | AutoCAD (any release with AutoLISP), BricsCAD, ZWCAD, GstarCAD, ProgeCAD and other IntelliCAD-based platforms. AutoCAD LT needs a LISP enabler. No .NET, no ObjectARX, no installer. |
| Author | YZ, August 2026 |
| Licence | Free to use, supplied “as is” with no warranty. |
References
- NUMSTAMP LISP — incremental numbering with a full content builder
- BARB LISP — leader arrows sized the same way, without a balloon
- Drawing scale chart — what DIMSCALE should be at each scale
- More free AutoLISP routines on this site
- Wisey’s Steel Shapes — free structural steel section drawing program