Making signs on a CNC router
Short answer
A good sign is mostly design and finishing, not machining. V-carve the lettering, pick a material that holds the detail, and spend your effort on contrast between letters and background. The carving is the fast part.
The decisions, in the order they matter
- Material, because it decides how much detail can survive.
- Lettering style and size, because that decides the bit and the depth.
- Background treatment, which is what most of the visual impact comes from.
- Finishing, which is where a good sign becomes a great one.
- Hanging, which is the step people forget until the end.
Material
| Material | Detail | Notes |
|---|---|---|
| Hard maple, cherry | Excellent | Crisp lettering. Watch for burning. |
| Walnut | Very good | Dark, forgiving, premium look. Paint fill shows beautifully. |
| Poplar | Good | Cheap and stable. Paint it; the colour is unremarkable. |
| Pine | Fair | Fuzzy edges, knots. Fine for rustic work. See softwoods. |
| Red oak | Poor for fine detail | Open pores crumble small serifs. Good for bold text. |
| MDF | Very good | Perfect for painted signs. Seal the edges. Indoor only. |
| Cedar, redwood | Fair | Weather resistant, soft. Good for outdoor rustic signs. |
| Solid surface | Excellent | Holds the finest detail, machines cleanly, weatherproof. |
Lettering
- V-carve is what makes lettering look professional. Sharp corners a round bit cannot produce.
- 60 degrees is the general purpose angle. 90 for large text or thin material, 30 for very fine detail. See V-bits.
- Watch the depth on wide strokes. A bold font with thick strokes can carve surprisingly deep. Set a flat depth if needed.
- Convert text to outlines before toolpathing, always.
- Check small text against the bit. Detail narrower than the tip will not appear.
- Keep a sharp V-bit for final lettering. The tip is what makes the corners, and it is the first part to wear.
Background treatments
Raised lettering
Pocket the background away so the text stands proud. Bold and tactile.
Carved lettering
V-carve into a flat surface. Fast, clean, the default.
Textured background
A texture toolpath around raised text, which hides tool marks and adds depth.
Paint fill
Carved letters filled with paint. Maximum contrast for the least effort.
Inlay
Contrasting wood set into the carving. The highest end look. See inlay.
The paint fill technique
The trick is sealing before painting, so paint cannot bleed into the grain around the letters:
- Sand the face smooth before carving.
- Seal the whole face with a clear finish and let it cure. This is the step that prevents bleed.
- Carve the lettering through the seal coat.
- Paint into the carving, slightly over the edges. Do not be delicate.
- When dry, sand the face back. The paint comes off the sealed surface and stays in the carving.
- Finish the whole piece.
Hanging
- Keyhole slots are the clean answer: the sign sits flat against the wall on a single screw. Remember the sign hangs from the top of the slot.
- Check the slot depth against your material thickness so it does not break through a thin panel.
- Two slots for a wide sign, so it cannot rotate.
- Outdoor signs need outdoor hardware and a finish rated for it, reapplied on a schedule.
Further viewing