CNC Engraved Text: Size and Depth for Readable Marks

CNC engraved text is a common way to add part numbers and labels to a machined part, and very small text is where it gets difficult.

How Do You Engrave Very Small Text on a CNC Machine?

Start by making the text larger and the depth realistic, before you change tools. Very shallow marks fight machine flatness and runout more than tool choice, and laser marking is often the better route for tiny text.

An r/CNC user was trying to engrave text only 0.02 mm deep with a fine-tipped 30° V-bit and couldn't get a clean result. The part was wood, but the replies apply to metal too. At that depth, they said, machine flatness and runout matter more than the brand of bit, so surface a scrap piece and test small patches first. Several suggested a laser instead.

What limits CNC engraved text

• Depth sets stroke width. A V-bit cuts wider as it goes deeper, so line weight is controlled by depth.
• The tool tip sets the smallest feature. Fine tips reach small counters but break more easily.
• Flatness and runout. At very shallow depths, small height errors make some letters vanish.

Size and depth guidance

Published numbers vary, so treat these as starting points:

• One engraving process reference gives typical text depths of 0.13–0.5 mm and a practical minimum character height of about 1.5 mm, or about 2.5 mm if the groove must hold paint fill.
• GL CNC Machining also treats about 1.5 mm character height as a practical floor on metal, and says laser marking is the cheaper route if the mark only needs to be visible.
• JLCCNC's text milling guide says that below about 4 mm character height, centerline engraving with a V-bit is almost always the right approach.

Design tips

• Use a single-line font where possible. Outline fonts need pocketing, which adds cycle time.
• Pick a bold sans-serif font and check the smallest counters (e, 8, B) at final size.
• Think about the finish. GL notes that a mark cut to the wrong depth can disappear after anodizing.

Related: as-milled surface finish and stock allowance for anodized surfaces.

At DigiForge

Our CNC service covers 3-, 4- and 5-axis milling and turning. Put the text, its height, and its depth on the drawing so it can be reviewed with the rest of the part. If you need engraving or laser marking, ask us when you quote.