How to Fix Dimension Text Too Small to Read & Missing Arrowheads in CAD
Calibrate DIMSCALE, Annotative Dimension Scales (CANNOSCALE), and DIMLFAC so dimension text height and arrowheads plot at exact ISO/ASME millimeter heights.
⚡ Quick Executive Fix
Open DIMSTYLE (D) > Modify > Fit tab: either check 'Annotative' (synchronizes automatically with CANNOSCALE) or set 'Use overall scale of (DIMSCALE)' to your target plot scale factor (e.g., 50 for a 1:50 drawing).
1. Engineering Root-Cause Diagnosis inside the AC1032 DWG Database
When an engineer draws a `12,000 mm` building bay in Model Space at `1:1` real-world units and places a linear dimension (`DIMLINEAR`), the dimension appears as a simple line with invisible text and missing arrowheads. Zooming in `500x` at the midpoint reveals that the text is actually there—it is simply `2.5 mm` tall against a `12,000 mm` wall because `DIMSCALE` is set to `1.0` instead of the sheet's plot scale (`50.0` or `100.0`).
2. Step-by-Step Resolution Protocol in AutoCAD & GstarCAD 2027
1. Method A: Scale Dimension Features via DIMSCALE (Classic Model Space)
Type D (`DIMSTYLE`), click Modify → Text, set Text Height (`DIMTXT`) to your target plotted paper height (`2.5 mm` per ISO 3098 or `3.0 mm`), then switch to the Fit tab and set Use overall scale of (`DIMSCALE`) to `50` (for `1:50`) or `100` (for `1:100`).
2. Method B: Enable Annotative Scaling (Multi-Scale Layouts)
In the DIMSTYLE → Fit tab, check Annotative. Set your Model Space status bar scale (`CANNOSCALE`) to `1:100`. GstarCAD 2027 automatically multiplies the `2.5 mm` paper height by `100` (`250 mm` in Model Space).
3. Never Mutate DIMLFAC to Fix Small Text!
Beginners sometimes change DIMLFAC (Linear Scale Factor on the Primary Units tab) instead of `DIMSCALE`. **Warning:** `DIMLFAC` multiplies the *measured numeric value* (`1000 mm` becomes `50000 mm`), not the text size! Always keep `DIMLFAC = 1.0` for `1:1` Model Space geometry.
3. Automated AutoLISP Diagnostic & Repair Script (C:FIXDIMSCALE)
Load the following production AutoLISP routine into GstarCAD 2027 or AutoCAD via APPLOAD (or add it to gcaddoc.lsp) to automate this repair across affected project files:
(defun C:FIXDIMSCALE ( / scaleFac)
(setq scaleFac (getreal "\nEnter target drawing plot scale denominator (e.g. 50 for 1:50, 100 for 1:100) <100>: "))
(if (null scaleFac) (setq scaleFac 100.0))
(setvar "DIMTXT" 2.5)
(setvar "DIMASZ" 2.5)
(setvar "DIMEXE" 1.25)
(setvar "DIMEXO" 0.625)
(setvar "DIMLFAC" 1.0)
(setvar "DIMSCALE" scaleFac)
(command "_.-DIMSTYLE" "_Apply" "_All" "")
(princ (strcat "\n[FIXDIMSCALE] Applied ISO 2.5mm text/arrows at 1:" (rtos scaleFac 2 0) " scale."))
(princ)
)4. Diagnostic System Variables & Edge-Case Matrix
| Failure Symptom / Scenario | Command / SysVar | Production Remediation Rule |
|---|---|---|
| Dimension text & arrows are microscopic | DIMSCALE = 50 / 100 |
Overall feature multiplier is 1.0; set to inverse of plot scale (e.g. 100). |
| Arrowheads disappear on narrow slots | DIMATFIT / DIMTIX |
Insufficient space between extension lines; enable Text & Arrows outside. |
| Dimension reads 25400 instead of 1000 | DIMLFAC = 1.0 |
Linear measurement multiplier was altered; reset DIMLFAC strictly to 1.0. |
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