Currently using AutoCAD C3D 2022 on Windows 10 but this likely applies to most AutoCAD installs.
A client specified that we use the Figtree font for updating their standard details. Figtree is a nice typeface created by Erik Kennedy and distributed for free on Google Fonts.
To use truetype fonts in AutoCAD you must install them in Windows before launching the program.
Figtree.zip comes with a few .ttf files that we can install, "Figtree-VariableFont_wght.ttf" being the most obvious.
In CAD everything seems fine, select some text inside an mtext block, click the "B" icon and it turns bold.
It also looks correct in the print preview, but when plotting with the built in PDF driver the bold text is not bold in the resulting PDF.
The bolding is surprisingly shown when plotting directly to a physical printer or when using a different PDF device, such as Bluebeam or Microsoft's PDF printers.
[Bold text can also be shown by making a text style with a width other than 1 - this forces AutoCAD to convert the truetype font to linework which looks jagged and is not actual text in the output PDF.]
I believe the problem is that AutoCAD's built in PDF driver does not fully support Variable Fonts.
Here is the README included with Figtree:
Figtree Variable Font
=====================
This download contains Figtree as both variable fonts and static fonts.
Figtree is a variable font with this axis:
wght
This means all the styles are contained in these files:
Figtree-VariableFont_wght.ttf
Figtree-Italic-VariableFont_wght.ttf
If your app fully supports variable fonts, you can now pick intermediate styles
that aren’t available as static fonts. Not all apps support variable fonts, and
in those cases you can use the static font files for Figtree:
static/Figtree-Light.ttf
static/Figtree-Regular.ttf
static/Figtree-Medium.ttf
static/Figtree-SemiBold.ttf
static/Figtree-Bold.ttf
static/Figtree-ExtraBold.ttf
static/Figtree-Black.ttf
static/Figtree-LightItalic.ttf
static/Figtree-Italic.ttf
static/Figtree-MediumItalic.ttf
static/Figtree-SemiBoldItalic.ttf
static/Figtree-BoldItalic.ttf
static/Figtree-ExtraBoldItalic.ttf
static/Figtree-BlackItalic.ttf
The solution that worked for me was to remove Figtree (Figtree-VariableFont_wght.ttf) from the C:\Windows\Fonts and then install two fonts from the "static" directory in the original download, Figtree-Regular.ttf and Figtree-Bold.ttf.
After closing and relaunching AutoCAD with the "static" fonts installed I was able to plot using the same DWG To PDF driver and the fonts in the PDF appeared bold, as expected.