Material Tabs: Holding Parts in the Sheet

Material tabs interrupt a cutting contour so small bridges of material remain, holding the part in the sheet until the job finishes. Without them a part comes free as its contour completes, and on a laser or waterjet a loose part can tilt, move, or interfere with the rest of the cut.

Where the settings are

Tabs are part of the contour cutting operation for laser, plasma and waterjet, the sixth icon in the row in the Toolpaths section of the CamDRAW docker.

In the operation window, the Tabs section is collapsed by default. Click the header to expand it.

The fields

Tabs switches the function on for this operation.

Width is the width of each bridge, measured along the contour. This is how much uncut material remains.

Number is how many bridges are placed on each contour.

Automatic position distributes them around the contour for you. Switched off, you place them yourself.

Scaling changes only how large the tab markers are drawn on the CorelDRAW page. It is a display setting and has no effect on machining.

Positioning tabs by hand

Once tabs are switched on, they appear on the CorelDRAW page as red dots on the contour.

With Automatic position switched off, those dots can be dragged with the mouse to anywhere on the contour. That is how you decide exactly where the bridges sit.

Manual placement matters more than it sounds. Put a tab on a straight edge rather than on a corner, and on a face that will not be visible on the finished part, because a bridge always leaves a small mark that has to be cleaned up afterwards.

Choosing a width

Wide enough to hold, narrow enough to break or cut away cleanly.

Thin material and small parts need very little. Thicker material and heavier parts need more, and often more bridges rather than wider ones, because several small tabs hold better than one large one and are easier to remove.

A default width per tool can be stored in the tool library, on the Tabs tab. That saves setting it in every operation for a tool you always use in the same material.

How many

Two is a sensible minimum on anything round, so the part cannot rotate. Longer parts need more, distributed so no unsupported span is long enough to droop.

Think about where the part will be after the cut rather than where the contour is convenient. A part held at one end only will tilt.

Combining with leads

Tabs and leads work together on the same contour. Leads control where the cut starts, tabs control where it stays connected. Both are set in the same operation window, in adjacent collapsible sections.

Check that a lead does not land on top of a tab. The preview on the page shows both, so a collision is visible before machining.

Checking before cutting

The preview updates as you change the values. After generating the program with the G1 G2 button in the NC program section, the 3D view shows the finished path with the interruptions in place.

Step through it with the slider under the 3D view if you want to confirm exactly where the cut stops and restarts.

When to leave them off

Not every job needs them. Parts held down by vacuum, work with a sacrificial backing board, and engraving that does not cut through all need nothing. Tabs cost cleanup time, so they are worth using when the alternative is a part moving mid-cut.