Embroidery, which does not use vectors at all

The file is a list of needle positions

This is the single most misunderstood thing in the trade. An embroidery machine does not read vectors. It reads a stitch file (DST (Tajima), PES (Brother), EXP (Melco), JEF (Janome), VP3 (Husqvarna)) which stores a sequence of needle coordinates, jumps, trims and colour stops.

Your vector artwork is a reference. Somebody, or some software, must decide stitch type, direction, density, underlay and compensation for every area. That process is digitising, and it is a skilled trade employing a great many people in Surat, Tiruppur, Ludhiana and Karur.

The three stitch types

• Run stitch: a single line of stitches. Outlines, fine detail, stems.
• Satin stitch: zigzag back and forth across a shape, giving the glossy raised look. Used for lettering and borders. Works between about 1.2 mm and 12 mm wide. Narrower than 1.2 mm and the needle perforates the fabric into a line; wider than 12 mm and the threads snag and sag, so a wide area is split or filled instead.
• Fill stitch (tatami): rows of run stitches covering a large area, with a stitch direction and a pattern of offsets to stop a visible line forming.

Direction is a design decision. A fill’s angle changes how light catches it, and a good digitiser varies the angle between adjacent areas so they read as separate shapes without an outline.

Underlay, density and pull

Three parameters that make the difference between a clean badge and a puckered mess.

Underlay is a first, sparse layer of stitching that stabilises the fabric and gives the top stitches something to sit on. Without it, satin stitches sink into the pile of a towel or a fleece and disappear.

Density is the spacing between stitches, typically 0.35 to 0.45 mm for a satin. Too loose and the fabric shows through; too dense and you get a stiff plate that perforates the cloth and breaks needles.

Pull compensation is the one nobody expects. As the needle pulls thread through, the fabric is drawn inwards across the stitch direction. A shape therefore comes out narrower than drawn, and the digitiser widens it (typically 0.2 to 0.3 mm on each side) to compensate. Knitwear pulls far more than woven cloth, so the same design needs different compensation on a polo shirt and on a cap.

Push is the complement: the shape grows slightly along the stitch direction. A circle digitised without compensation comes out as an oval.

What this means for your design

• Nothing below about 1.5 mm survives. It disappears into the thread.
• Text below about 5 mm cap height becomes a smudge. For lowercase, 6 mm.
• No gradients, no tints. Colours become a short list of thread codes from one brand’s chart: Madeira, Isacord, Robison-Anton. Ask which the shop uses and pick from their chart.
• Every colour change is a machine stop. Five colours cost more than two, in time and in thread changes, on every single garment.
• Stitch count is the price. A shop quotes per thousand stitches. A detailed chest logo at 12,000 stitches costs roughly twice a simple one at 6,000, on every unit.
• Small text inside a fill needs to be a gap in the fill, not stitched on top, or it fills in.

Doing it yourself, free

Ink/Stitch is an Inkscape extension that produces usable DST, PES and other formats. It is free, actively developed, and it will take you from a vector shape to a stitch file with satin columns, fills, underlay and manual stitch direction.

The workflow: draw the shape in Inkscape, use Ink/Stitch’s Params dialog to set stitch type and density per object, use the satin-column tools to control direction, simulate the result, then export. It has a real learning curve and it is a complete tool.

It will not replace a good digitiser on a complex chest logo, where experience with a specific fabric is what you are paying for. For a simple one- or two-colour mark, it works.

The test that settles everything

Ask for a sew-out. A single stitched sample on the actual fabric, before the run. Most shops will do one for a small fee or free on a decent order, and it shows you pull, density, colour and legibility in one object.

Nothing on a screen predicts embroidery. The sew-out is the proof, and skipping it on a 500-shirt order is the most expensive economy in this module.