6. V-carving and inlay#

Four operations cut with a pointed tool, and all four rest on one fact: with a V-bit, width and depth go together. The deeper the tip, the wider the groove. V-Carve, Photo V-Carve and Inlay use it one way round — the width the shape needs decides how deep the tip goes. Fluting uses it the other way: you say how deep, and the groove comes out as wide as that depth makes it.

V-Carve#

A V-carve makes letters and shapes look carved rather than routed. Instead of a constant-depth pocket with vertical walls, the tool dives where the shape is wide and lifts where it narrows — so a serif tapers to nothing and a corner comes to a crisp point, exactly the way a hand-cut letter does.

Select closed geometry, pick a V-bit or a taper, set Max Depth, and generate. There is no stepover and no strategy: the shape's own width decides the path.

The toolpath runs down the middle of each stroke, following its centreline. Where a stroke is wide the tool goes deep; where it narrows to a serif it lifts to nothing.

The same job simulated. The letters have sloped walls and the serifs come to a point — neither of which a flat cutter can produce.

Max Depth is a limit, not a target. Most of a carve never reaches it; it stops the tool bottoming out in the widest parts of a broad shape. If your letters come out looking flat-bottomed and blunt, that limit is what you're hitting.

The form tells you the consequence of the number you typed — "cuts at most 4.00 mm wide at full depth" for a 90° bit at 2 mm. That is the width-to-depth law stated for your tool, and it is worth reading before you commit: if the widest part of your lettering is narrower than that figure, nothing in the job will ever reach Max Depth at all.

Holes and counters work without being declared. The bowl of an o, the triangle in an A, an island inside a shape — the app reads them off the geometry, the same as a pocket does.

Which bit#

A taper's ball tip means it can enter a stroke narrower than itself and leave a round-bottomed groove instead of refusing the job, which is what makes it good for fine lettering and small detail. A V-bit closes to a true point and is the sharper result.

Remember the two conventions from chapter 3: a V-bit's angle is included, a taper's is per side.

Photo V-Carve#

Rasters a photograph as a field of V-grooves whose depth follows image brightness. Dark areas cut deeper, and because a deeper cut with a V-bit is a wider cut, the dark parts of the picture become broad grooves and the light parts fine ones. Flood the finished board with paint and sand the face back and the image appears in the grooves.

V-bits only — the effect depends on the width-to-depth relationship of a true cone.

Depth is the resolution control#

This is the part that isn't obvious. Line spacing is not a setting — it is the width of the deepest groove, so that the darkest lines just touch and nothing is cut twice. So the depth range you choose decides how many lines there are:

• A shallower carve is a finer one — narrower grooves, more lines, more detail, less contrast.
• A deeper carve has more contrast and fewer, wider lines.

The form shows the resulting groove width range and line count as you change the depths, so you can trade the two off directly rather than guessing.

Inlay#

An inlay fits a plug of one wood into a socket cut in another, so tightly that the seam disappears. It is two operations on two boards, and the geometry that makes it work is worth understanding before you cut anything.

Why V-walls#

If you cut a socket with straight walls and a plug to match, the plug has to be exactly the size of the hole. A thousandth too big and it won't go in; a thousandth too small and you have a visible line all round.

Cut both with the same V angle and the problem goes away. The plug is a wedge, the socket is a matching wedge, and the plug simply descends until the two wall angles meet. Where it stops is where the fit is tight — so you make the plug deliberately too deep, guaranteeing it lands on its walls and never on the floor.

Three consequences follow from that picture, and they explain every field in the form:

1. The walls are the joint. They must be cut with the same tool angle on both halves.
2. The floor must never touch — that is the Glue Gap, and it is what gives the glue somewhere to go instead of holding the joint open.
3. The face is made by planing, not by machining. You press the plug in, let the glue cure, and plane or sand the assembly back to the female board's face. The seam closes as you approach it.

The form#

You generate the two halves separately, from the same drawing:

Lettering is cut by size. Small text, whose strokes the V-bit spans from edge to edge at the inlay depth, is V-carved straight into a socket of exactly the strokes' shape. Large text — any letter with a stroke wider than that — is cut like every other shape instead: the end mill clears a flat floor and the V-bit forms the walls, so a big bold letter gets a proper socket and a plug that seats.

The female doubles as a pocket with crisp V walls. Its V-bit never goes below the floor: the end mill clears the floor flat, and the V-bit cuts the walls down to meet it, going round the floor's edge at full depth and clearing the corners the end mill can't reach. So the Female half on its own is a flat-bottomed pocket whose walls are sloped and whose inside corners are as sharp as the V-bit can make them — handy for a recess, a sign's lettering or a tray, with nothing to fill it.

Invert answers the same question as Invert Pocket: a design inside a field can be read two ways, and only you know which wood is meant to show. The form says which reading it is using in plain words — "the inner shapes are the plug" versus "the field around the inner shapes is the plug" — so you can check it rather than infer it.

Cut-out Outline (male, on by default) frees the plug from the sheet. Generate clears everything round the plug down to the plug depth and adds an outside Profile right through the stock, run after the plug's own cuts, along the plug's cut-out line:

• One shape (a bowtie, an outline drawing) — the cut-out is the shape's own outline, so the profile goes on the shape's own path. Nothing new is drawn; a copy laid over the original would put every line on the canvas twice.
• Lettering, or a mirrored shape that isn't symmetric — a new path is drawn, a band wrapped round all of it (or the mirrored outline), and the profile goes on that. It is redrawn on every Generate.
• A nested design gets one cut-out, round the outermost shape: the inner levels stand in its holes on the same piece of board.

The profile is an ordinary operation: open it to add tabs (a small plug cut free at full depth can move), or to change its depth. To use a boundary of your own instead, untick the option, draw the boundary round the plug, select both and use Invert — the plug then clears to your boundary.

Mirror matters because the male board gets flipped over to go in. If your inlay has any handedness — lettering, a signature, anything not symmetrical — the plug must be machined as a mirror image or it will read backwards in the finished piece. Cutting a mirrored inlay the wrong way round is the mistake that costs a board.

Use a V-bit, not a taper#

A cone is its own mirror image, so a V-bit plug and its socket close completely.

A taper cannot. Its ball rounds the foot of the plug wall — the plug's widest end — while the socket's rounding sits at its narrowest, the deep end. Flip them together and those two roundings don't meet at the finished face. The result is a hairline gap right where you'll be looking at it, up to the tip radius wide: about 0.20 mm for a 0.25 mm tip, 0.30 mm for a 0.5 mm tip.

The angle makes no difference — a taper at 20° and at 60° gives the same gap. The plug still seats perfectly well; it just leaves a visible line. The form says so on the tool row.

This is geometry, not a defect. If you want a taper's fine detail somewhere, use it for the V-carving in that chapter section and keep a V-bit for inlay walls.

Fluting#

Fluting carves along a line — the flutes down a column or a table leg, a groove that swells from nothing to full depth and fades out again — with the depth set by a height profile you draw. The tool runs on the line itself, as a centerline cut, and only Z changes as it goes. Select one or more paths (open strokes are the usual case; a closed one works too) and open CAM Operations → Fluting.

Drag the points to shape the flute. The two ends move only up and down; the points between move anywhere between their neighbours. A dragged point snaps to the surface, to full depth and to the depth of the point on either side, which makes a level run easy to get. Click a point to select it, then type its exact position and depth underneath.

One profile fits every path. It is stretched over each path's own length, so the same settings flute a short stroke and a long one alike. A compound path takes the whole profile over each of its parts.

Which end is the start depends on how the path was drawn. It only matters for a profile that isn't symmetrical — deep at one end, fading at the other. If it comes out the wrong way round, tick Reverse rather than redrawing anything.

The default profile: in from nothing to full depth over the first fifth of the path, level through the middle, and out again over the last fifth.

An open stroke is cut there and back, so the tool is already where the next pass starts and never lifts between passes; a closed path goes round the same way every time. Where the profile drops steeper than 45° the tool goes straight down at the plunge feed rather than diving along the slope at the cutting feed.

Next#

• 7. 3D work — carving a relief from an STL or a depth-map image
• 10. Simulating and exporting — checking a job before you cut it