Last updated July 28, 2026
Nineteen commands for mechanical detailing in one file, plus fourteen drawings holding the geometric tolerance symbols they insert. Drill holes, tapped holes, counterbored and countersunk holes, dowels, section arrows, break marks, feature control frames, datum symbols and a set of text tools. It is by Shirley Westbrook and dated 6 May 1989, which makes it one of the oldest pieces of working code in this library.
The author’s terms are as informal as the date suggests: the routines are “free for you to do with what you wish”, with an invitation to send comments over CompuServe.
Rename the file before you go anywhere near your support path
This is the one thing that matters more than anything else on this page.
The LISP file in this archive is called ACAD.LSP. That is not an ordinary name — it is the name AutoCAD looks for and loads automatically, on its own, every time it opens a drawing. Put this file anywhere on your support file search path and its nineteen commands load into every drawing you touch from then on, without you asking.
Worse, if you already have an ACAD.LSP of your own — and many offices do, holding their standards and startup customisation — AutoCAD will find whichever comes first on the path. Yours may quietly stop loading, and the symptom is that your own customisation “just stopped working” with nothing obvious to point at.
Rename it to something else, MECH.LSP for instance, before you put it anywhere permanent. Then load it deliberately like any other routine. Nothing in the code depends on the file name.
The nineteen commands
- Holes — DHOLE (drilled), THOLE (tapped), VTHOLE, DHOLECB (counterbored), DHOLECD (countersunk), DOWEL.
- Tolerancing — TOL for feature control frames and DATUM for datum symbols, both drawing on the supplied symbol drawings.
- Annotation — DOWNOTE, LABEL, NOTE-style text placement via TXTIN, CHGTXT for changing text, ARCTEX for text on an arc, and CR.
- Drafting marks — CRACK for a break line, FMARK, SECARR for section arrows.
- Utilities — SETPICK for the pick box, PACK.
The fourteen drawing files are the tolerance symbol library: a set named TOLA through TOLL covering the geometric characteristic symbols, plus TOLBOX and DATBOX for the frames they sit in. They have to be somewhere AutoCAD can find them or the TOL and DATUM commands will fail when they try to insert.
It expects a particular drawing setup
The author is explicit about this in the header, and it is the second thing that will stop the routines working as intended. They reference specific layers and text styles by name: hidlin for hidden lines and cenlin for centre lines, and the text styles standard (a simplex font) and fancy (a complex font).
If your drawing does not have those, you will either get errors or geometry landing on the wrong layer. Create them to match, or edit the names in the file — they appear as plain strings and are straightforward to change.
One other period detail: the file calls a memory-management function from the DOS era on its first line. It is harmless on modern releases, which simply ignore it, but it tells you what era of AutoCAD this was built for.
How to load it
Unzip the archive somewhere outside your support path. Rename ACAD.LSP as described above. Put the renamed file and the fourteen DWG files in one folder on the search path, then load the LISP file with APPLOAD. Our AutoLISP guide covers loading and the search path.
Test one hole command in a scratch drawing before committing to it. With nineteen commands and a 1989 vintage, working out which ones still behave is a job best done somewhere harmless.
Compatibility notes
1989, so written-for rather than tested-on by a wide margin — this predates most of the other routines on this site. The hole and annotation commands are plain AutoLISP driving standard AutoCAD commands, which gives them a fair chance; the tolerance commands depend on inserting the supplied drawings, which should still work since DWG files of that age still open.
No dialog boxes and no Express Tools calls, so nothing requires the full product; LT users on LT 2024 or later, the release that brought AutoLISP to LT, could try it. See what runs on AutoCAD LT.
Download
| Name: | Mechanical Drafting Lisp Collection |
| Description: | This file is a collection of AutoLisp routines that are to use while doing mechanical drafting and design. Various routines to draw drill holes, threaded holes, etc. |
| Type: | AutoCAD AutoLISP Routine |
| Author: | Shirley Westbrook |
| File Size: | 15 Kb |
| Cost: | Free |
| Worked on: | AutoCAD |
| Download File: | Mech2lsp.zip |
Related routines
- BOLTS — metric fasteners for the same detail drawings.
- SLOT — slotted holes, which this collection does not cover.
- ATEXT — a standalone text-on-arc routine.