How do I carve a photo as a pattern of drilled dots? (Half Toner gadget)

What it is

Half Toner turns an image into a halftone: a grid of holes whose size carries the picture. The library explains that it works by drilling holes to different depths with a V-bit or a ball nose tool. The darker the area, the deeper the hole, and because those tools get wider with depth, the deeper holes are also wider dots.

Important detail: the gadget produces a toolpath, not dot vectors. It reads its picture from a 3D component, so there must be a component in the job before you run it.

Steps

1. Download the version 12 build from the gadget library and install it with Gadgets > Install New Gadget.
2. Import your image, then on the Modeling tab use Create Component from Bitmap to turn it into a component. The gadget will not run without one.
3. Choose Gadgets > Halftoner.
4. Set the options:

• Maximum Hole Radius: the size limit of the largest dot. The library ties this to how far the tool drills into the material.
• Screen Angle: the angle at which the rows of holes are lined up.
• Retract Z: the safe height the tool lifts to between holes (spelled "Rectract Z" on the library page).

5. Click OK, then preview the toolpath.

Judgment

• Pick a photo with strong contrast and a plain background. Halftones throw away fine detail, and the picture reads best from a distance.
• The hole spacing sets the detail. Smaller maximum holes give more dots and more detail but a much longer run, because every dot is a separate plunge and retract.
• A lower Retract Z shortens the job, as long as it still clears clamps and the surface.
• Material with a contrasting top layer, or a painted face cut through to bare stock, makes the dots stand out.

Limits

• Aspire only, because it depends on a 3D component.
• The public page does not publish dot spacing rules or feed settings. Run a small test patch on scrap first.
• This is different from the Photo V-Carve toolpath, which cuts lines of varying width instead of dots.

Pro tips

• Preview with the exact bit you will use. Dot width for a given depth depends on the tool angle or ball diameter.
• See the entry on Create Component from Bitmap for getting a clean component from a photo.