Pocket Machining and Islands in CamDRAW

Pocket machining clears the material inside a closed contour. Where contour milling follows a line, pocketing removes everything within it, working from the inside outwards.

Closed curves only

Only closed curves are supported. A closed curve is one where the start node and the end node share the same X-Y position: a circle, a rectangle, a letter, a traced outline that joins up.

An open curve cannot be pocketed, because there is no defined inside. If the operation refuses your object, this is almost always why.

Creating the operation

Select the drawing object in CorelDRAW, then click the second icon in the row of six in the Toolpaths section of the CamDRAW docker. The pocket machining window opens and a preview appears on the page.

The dialog

Name and Tool work as in every operation. The tool icon beside the dropdown opens the tool library.

Contour adjustment offers two things here rather than the full set from contour milling. Show tool diameter draws the path at the real tool width, which is the quickest way to see whether material is left standing in the corners. Climb or conventional sets the milling direction.

There is no inside or outside choice, because a pocket is by definition inside.

Allowance leaves a pocket allowance, an offset from the contour, for a separate finishing pass.

Machining parameters are the same four Z values as contour milling: safety height, plunge height, starting height and final depth.

Curve precision sets the length of the straight segments used to approximate curves.

Where the path spacing comes from

The distance between neighbouring passes is not in this window. It is stored with the tool.

Open the tool list, select your tool and go to the Cutting data tab. Path spacing is expressed as a percentage of the tool diameter. It should not exceed 50 percent: beyond that, uncut material is left standing between passes.

The Cutting depth on the same tab governs how much is taken per pass on the way down to the final depth.

Setting these properly per tool means you set them once rather than in every operation.

Islands from combined objects

This is the part worth knowing.

Combine several closed curves in CorelDRAW and pocket the result, and CamDRAW works out what should be cleared and what should be left standing. A rectangle inside another rectangle produces a pocket with an island in the middle.

The same logic handles more complex arrangements. Several combined shapes, partly overlapping, produce a path that clears the correct areas and leaves the rest.

Text works the same way. Pocketing a text object clears the letterforms while leaving the counters, so the middle of an O stays where it belongs.

Switch on Show tool diameter to check the result before machining. It shows exactly what is removed and reveals material left in corners where the tool radius cannot reach.

The machining order

Pocket paths are always sorted from the inside outwards. This is deliberate: it keeps the tool engaged in material and avoids the finished edge being cut first and then disturbed.

After creating it

The operation is listed in the Toolpaths section. Right-click it for Edit, Generate and Delete. Use Generate to recalculate after changing the underlying drawing objects.