Underlay and pull compensation

The underlay is a layer of stitches sewn first, under the stitches you see. It holds the fabric flat and still, so the top stitches lie evenly and the fabric doesn't show through them. Pull compensation answers the other thing the fabric does: the thread pulls it in as it is sewn, so a satin comes out narrower than drawn and a fill's rows shorter. With it, NextStitch sews them a little wider or longer, and the shape ends up the size you drew.

Both are set per object. Underlay in the bar above the canvas (in the Stitch view or Simulation) is a switch with a gear beside it; the same settings are on the Underlay tab of Stitch settings in the right rail. The pull compensation is on the Fill tab of Stitch settings, and behind the gear beside Type in the bar. Fill and underlay explains how a fill and its underlay are sewn; this page goes through every setting.

Each figure is the stitch engine's own plan: every line is a stitch, sewn where NextStitch would sew it, the underlay in violet or magenta, and the numbers under a figure are counted from those stitches.

Automatic, Custom and None

Every new shape starts on Automatic: NextStitch chooses the underlay by the shape's width and size, as it sews, and the menu says what it chose under Sewn as, for example "Edge walk + Zigzag, for a 4.0 mm column". The choice follows the shape: make it wider, narrower or smaller and the underlay changes with it.

• Custom shows the settings, starting from what Automatic chose, so nothing changes until you edit something.

• None sews no underlay.

• The switch in the bar turns Automatic on and off; off is None. The gear opens the menu with all three.

Pull compensation has its own switch, Automatic pull compensation, which every new shape starts with too. A design saved before underlay was automatic keeps what it had. File ▸ Properties brings its shapes over in one step (Use automatic for … shapes), and its switch Automatic underlay and pull compensation for new shapes decides how the shapes you draw next start. A shape you set by hand keeps its own.

What Automatic chooses

A satin column, Satin (area) and an appliqué's satin cover get their underlay by the column's width:

The width is the one you set for a satin drawn as a line, the width most of the column has between two rails or along the strokes of Satin (area), and the cover's width for an appliqué. One width decides for the whole object.

Auto-fill, contour, circular and guided fills get an underlay when the area is at least 20 mm² and at least 3 mm across where it is thickest. It is an Edge run round the shape, then one layer of rows across the fill's rows, both 0.4 mm inside the edge. Its rows are three times the fill's row spacing apart (1.2 mm at the fill's 0.4 mm) and its stitches as long as the fill's. A smaller area gets none, and the menu says so.

An Outline sewn as a satin or a fill gets its own underlay by the same rules, by the outline's width or the size of its band.

These are the choices for a stable woven fabric, and for every design that does not apply its fabric. Switch on Apply fabric settings in File ▸ Properties ▸ Fabric and Automatic chooses for the fabric too: a stronger underlay and more pull compensation on a knit, a towel or a cap, a lighter underlay under a satin on a sheer fabric — but not on free-standing lace, which keeps Automatic as it is — and none on leather, and more pull the more the fabric stretches. Fabric and stabiliser has the table. Values you set by hand stay as they are.

Satin underlay layers

Under Custom, a satin's underlay is three switches, one per layer, and any of them can be on together. They are sewn in this order, before the satin:

• Center walk: a running stitch down the middle of the column, there and back. It holds a narrow column without showing at its edges.

• Edge walk: a running stitch up one side of the column and back down the other, just inside its edges. It keeps a wider column in shape, its edges crisp.

• Zigzag: a wide zigzag down the column and a second one back over the gaps, which together carry a dense, wide satin and lift it off the fabric.

In the figure each layer is on its own under the same column, 5 mm wide. The satin's own stitches are spread out, so you can see the layer under them.

Each layer has its own settings when it is on. On a new shape they start at these values:

• Center walk: Position across (%) moves it towards one side of the column, 50 % being the middle. Repeats is how many times it runs along the column: 2, there and back, unless you change it. With an odd number it ends at the column's far end, and the satin is sewn back from there. Stitch length (mm) starts at 1.5 mm.

• Edge walk: Stitch length (mm), 1.5 mm.

• Zigzag: Spacing (mm), the distance from one zig to the next, 3 mm. Max stitch (mm) splits zigzag stitches longer than it; empty, they are not split.

Where a satin layer lies

Each layer's Advanced sets where it lies in the column:

• Inset from the edge (mm), for the edge walk and the zigzag: how far in from the column's edges the layer stays, 0.4 mm unless you change it. A negative value, down to −1 mm, lays it outside the edges, where columns join and the underlay should hold the fabric under the joint. Inset (% of the width) adds a share of the column's width on top, from 0 to 50 %.

• End inset (mm): how far in from the column's ends the layer stops. More keeps it hidden under a pointed end; a negative value runs it up to 1 mm past the ends, where columns join. Empty keeps the ends the layer has always had. A layer whose two ends would meet is left out.

• One pass, for the zigzag of a satin column: the zigzag is sewn once, from the column's start to its end, instead of there and back. It is a lighter underlay, and it ends at the column's far end, so the satin is sewn back from there. Satin (area) and an appliqué's cover always sew their zigzag there and back, so they don't offer it.

Fill underlay

Under Custom, a fill's underlay has these settings. Fill underlay, on the Underlay tab and in the bar's menu alike, switches the layer on and off; the settings below it show while it is on.

• Edge run: a running stitch round the shape at the underlay's inset, sewn before its rows. It holds the edge down, so the fill's edge lies crisp and close to its neighbours.

• Angle(s) (deg): the direction of the underlay's rows. Empty is the fill's angle plus 90°, across the fill's rows, as the field shows. Type several angles, separated by commas, to sew one layer at each.

• Row spacing (mm): the distance between the underlay's rows. It starts at three times the fill's row spacing. Closer rows hold more and add stitches; wider rows are lighter.

• Inset from the edge (mm): how far inside the edge the underlay stays, so it doesn't peek out past the fill's last row. A fill underlay you switch on starts at 0.4 mm.

• Max stitch (mm): the longest stitch of the underlay's rows. It starts at the fill's Length.

• Skip the last stitch of each row: fewer stitches and less density where the rows turn.

The slider changes Row spacing (mm) on a new 30 × 20 mm fill. It opens at what Automatic sews there.

The fill's own rows start where the underlay ended, so the thread goes on from one to the other without a long move.

Pull compensation on a satin

The thread pulls a satin column in across its width, so it sews narrower than drawn. Pull compensation moves both ends of every satin stitch outward by its value, so the column sews to its width.

With Automatic pull compensation, under Stitch settings, NextStitch chooses it by the column's width: 0.05 × the width + 0.08 mm on each side, at least 0.1 mm and at most 0.35 mm. That is 0.18 mm for a 2 mm column, 0.28 mm for a 4 mm one, and 0.35 mm from 5.4 mm on. The value it chose is shown under the switch. The same rule applies to Satin (area), to an appliqué's satin cover by the cover's width, and to a satin Outline by the outline's width.

Switch Automatic off to set it yourself: Pull compensation (mm) starts from what NextStitch chose, and Pull in the bar shows the same value. Typing a value into Pull switches Automatic off too. The slider shows the end of a column drawn with two rails, the dashed lines, 2.4 mm apart.

• Pull compensation (%), under Advanced, adds a share of the column's width on each side, on top of the millimetres. A share grows with the column, which suits a column that changes its width.

• Per side gives each side a pull compensation of its own, Side 1 (mm) and Side 2 (mm), in the order of the column's rails. Both start from the value the column had, so nothing moves until you change one.

Pull compensation on a fill

The thread pulls a fill's rows in along their length, so the fill sews narrower than drawn in the direction of its rows. Pull compensation lengthens every row at both ends.

With Automatic pull compensation, NextStitch chooses it by how long the rows are: 0.1 mm plus 1/200 of the rows' mean length at each end, at least 0.1 mm and at most 0.3 mm. That is 0.2 mm for rows 20 mm long and 0.3 mm from 40 mm on, because a long row pulls in more than a short one. Switch it off to set Pull compensation (mm) yourself, from 0 to 1 mm; it starts from what NextStitch chose. The figure shows the right edge of a 30 × 20 mm fill, its outline dashed.

Auto-fill and a guided fill without a guide line take a fill's pull compensation; contour and circular fills have no row ends to lengthen. Only the fill's rows are lengthened, not its underlay. The same switch also chooses the pull compensation of a satin Outline on the shape. Where two areas meet edge to edge, the Overlap closes the gap in every direction: Fill settings.

Good starting values

• Leave Underlay and Automatic pull compensation on for new shapes, and bring an older design's shapes over with File ▸ Properties.

• Stretchy, napped or fluffy fabric wants a stronger underlay: a second layer of underlay rows under a fill, along its rows, and an edge walk and a zigzag under a satin. Choose the fabric and Apply fabric settings in File ▸ Properties, and Automatic does this for you. On a stable woven fabric and in small areas, a light one or none is enough.

• A satin column that sews narrower than drawn: raise its pull compensation a little, 0.05 mm at a time.

• A fill whose rows stop short of the edge: raise its pull compensation; a fill that leaves a gap to its neighbour: raise its Overlap.

• Under a pointed satin end the underlay shows: give the layer an End inset.