Contour Engraving With a Depth Regulator

Contour engraving traces the outline of a drawing object with the tool, producing a fine line. It looks similar to contour milling, and one crucial thing is different: there is no depth of cut.

Why there is no cutting depth

Milling works to a target Z. You tell it how deep to go and it steps down in increments until it gets there.

Engraving does not, because the depth of an engraving usually needs to follow the surface rather than a coordinate. Material is rarely perfectly flat, and over a 300 mm plate a few tenths of variation is normal. A few tenths is the entire depth of an engraving.

So the operation works with a constant engraving height and lets the machine handle the rest, typically through a depth regulator: a floating nose that rides on the material and keeps the tool a fixed distance below the surface.

Creating the operation

Select your objects in CorelDRAW, then click the fourth icon in the row of six in the Toolpaths section of the CamDRAW docker. The contour engraving window opens with a preview on the page.

Contour adjustment

Identical to contour milling. Tool center places the path on the line, inside or outside. Machining direction sets climb or conventional. Both directions allows either. Show tool diameter draws the path at real tool width.

For text engraving the path normally belongs on the line, not offset to one side. Offsetting makes lettering visibly heavier or lighter than drawn.

Machining parameters

Here the window differs from milling.

Safety height for rapid moves above the workpiece.

Plunge height where the plunging feed rate takes over.

Engraving height replaces the depth field. This is the Z plane where machining happens. With the Z zero on the workpiece surface it is often zero. For a depth regulator, set a negative value here as a preload, pressing the nose into the surface so it tracks reliably.

Number of cuts is how many times each contour is traversed. One pass is normal. Two or three on hard material, or where a deeper mark is wanted for paint fill.

Note what is absent: no final depth and no cutting depth. Nothing steps down.

Line width and the tool

With a conical graver the width of the engraved line depends on how deep the tip sits, and therefore on the tool angle. A steeper angle gives a narrower line at the same depth.

Store the graver in the tool library with its Diameter and Tool angle, both on the Dimensions tab of the tool list. With those recorded, the line width follows from the engraving height instead of being discovered on the first plate.

The tool shape is set on the General tab, as either cylindrical or conical.

Sequence, allowance and curve precision

Sequence sets automatic optimisation by shortest path, or the order the objects sit in on the CorelDRAW layer.

Allowance offsets the contour, rarely needed for engraving.

Curve precision sets the segment length used to approximate curves. This matters more in engraving than anywhere else: at 4 mm cap height a coarse setting shows as visible flats on every round stroke, while on a large plaque the same value is invisible.

When the surface is not flat and you have no depth regulator

Probe it. The measurement grid function measures a set of points across the workpiece and corrects Z from the result. It is hidden by default: click the gear icon at the top of the docker, and on the General tab tick Measuring grid, then click Save.

Filled letters instead of outlines

Contour engraving traces the shape. To clear the inside of letters so they read solid, use the area engraving operation, the fifth icon in the row, instead.