WELDMARK draws complete welding symbols — leader, arrowhead, reference line, weld symbol, size and pitch text, optional backing / weld-all-around / field flags, and up to three lines of tail notes — as native AutoCAD geometry.
What WeldMark does
Nothing is inserted as a block. Every symbol is drawn from lines, arcs, polylines and solids at the moment you place it.
That matters on a fabrication drawing, because a detailer can edit any symbol without exploding it first, and because there is no block library to ship, bind or lose when the drawing goes out to the shop.
No support files at all. The weld symbols on the dialog buttons are drawn from a table of vectors held in the file, so there is no slide library to install. The dialog definition is embedded as text, written to a temporary .dcl at run time, loaded, then deleted.
How to use it
- Load the routine with
APPLOAD, or put it on your support file search path. - Type
WELDMARK. - Pick the arrow tip — the spot on the joint the symbol points at.
- Pick the elbow, where the sloping leader turns into the reference line.
- Set the weld type, side, size and pitch, flags and tail notes.
- Keep picking pairs of points; press Enter to finish.
How it works
The reference line follows the leader direction. From the angle between the two picked points the routine works out which way the reference line should run — left-to-right leader, reference line to the right; right-to-left leader, reference line to the left.
Everything downstream — symbol position, text position, tail direction — is measured along that one angle, so the symbol reads correctly whichever way you drag it.
The dialog remembers every choice for the rest of the session, so placing twenty identical fillet welds means picking two points twenty times and pressing Enter — not re-answering the dialog each time.
Sides are handled by mirroring, not by a second set of code. The chosen symbol is drawn above the reference line — the “other side” position in AWS terms — and each entity is collected into a selection set as it is created. An arrow-side weld mirrors that set below the line and deletes the originals; a both-sides weld mirrors and keeps them; an other-side weld is already where it belongs.
A backing-weld arc is deliberately excluded from that mirror set. A backing symbol always sits opposite the main weld symbol, so mirroring it would put it on the wrong side.
Every dimension is a multiple of DIMSCALE, so the symbol comes out right for whatever scale the drawing is set up at. Text height is 0.094 × DIMSCALE unless the current style has a fixed height, in which case the style wins.
Notes and limits
- Native geometry, not blocks.
- No slide library and no separate .dcl to install.
- It repeats until you press Enter.
- Set
DIMSCALEfirst. - One undo group per symbol.
Download and details
| Name | WeldMark — place complete welding symbols to AWS A2.4 convention |
| Download | WeldMark.lsp — 40.0 KB, plain AutoLISP source. Downloads directly; no zip to unpack. |
| Type | AutoCAD AutoLISP routine |
| Command | WELDMARK |
| Requires | nothing extra — the dialog is written to a temporary file at run time and deleted again, so there is no .dcl to install. |
| Source size | 40.0 KB, 861 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
- Weld symbols chart: AWS A2.4 — the convention this draws to, with a printable chart
- AWELD LISP — another welding symbol routine, worth comparing
- TEXTWELD LISP — weld notes rather than symbols
- More free AutoLISP routines on this site
- Wisey’s Steel Shapes — free structural steel section drawing program