Three engraving methods, three different files

Because engraving removes material along a path rather than laying ink inside a shape. A print file describes areas to fill; an engraving file describes routes for a tool or a beam to travel. They can come from the same source artwork, but they are not the same output.

A normal font outline is two lines around each stroke — an engraver cutting that produces an outlined letter, not a solid one. Single-line geometry is one path down the middle of each stroke, which is what a rotary cutter or diamond drag follows to produce a stroke the width of the tool.

For raster fill on the right substrate, yes — that is one of the few places a bitmap is genuinely the correct input. For cutting or scoring, no: there are no paths in a photo for the beam to trace.

Convert it to paths, then decide the method. Once you have clean vector you can fill it for laser, generate a centreline for rotary, or score the outline — one conversion serves all three routes. Starting from the JPG you are stuck with fill only, at whatever quality the pixels allow.

Less than the artwork suggests. Fine text and tight counters close up on most substrates, and hairlines vanish on textured surfaces. Simplify before you engrave rather than discovering it on the finished piece — this is a judgement call, and it is yours, not the software's.