Plasma-cut sign lettering: fonts, sizes and bridges

Lettering is the part of a sign customers notice first, and the part most likely to go wrong on the table: centres that drop out, strokes that burn away, and letters that fall through the slats. Here’s how to get clean, readable plasma-cut text.

1. Choose how the letters are cut

• Cut-out letters in a plate (the classic sign): the letters are holes in the plate. Their centres (O, A, B, D, P, Q, R) are islands and need bridges.
• Loose metal letters: each letter is its own part, for mounting on a wall or welding to a frame. No bridges needed, but small letters can drop through the slats.
• Script lettering that joins up cuts as one piece, which is great for names and house signs.

2. Pick a font that survives the torch

• Stencil fonts (Allerta Stencil, Stardos Stencil, Saira Stencil, Black Ops One) already have bridges in every letter. They’re the safest choice for cut-out signs.
• Bold block fonts (Anton, Bebas Neue, Oswald Bold, Archivo Black) read from a distance and have thick strokes.
• Avoid hairline serifs and thin scripts: every stroke should be at least 2–3× the plate thickness, or it burns away.

3. Size it for the plate

Plate	Smallest practical letter height	Bridge width
16 ga / 1/16"	about 1"	1/8"
1/8"	about 1.5"	3/16"
3/16"	about 2"	1/4"
1/4"	about 2.5–3"	1/4"–5/16"

These are starting points for a typical air plasma. Holes smaller than the plate thickness cut poorly, so small punctuation and the insides of small “e”s are the first to suffer.

4. Add bridges to letter centres

Two bridges per island (top and bottom, or left and right) hold centres flat and square. Make bridges at least as wide as the plate is thick, and place them where they read naturally: a stencil look is part of the style.

5. Frame it and cut

A plate with a 1" border and 1/2" rounded corners looks finished. Cut the letters first and the outline last, so the plate stays put while the inside cuts happen.