PCB Edge Cuts

Edge cutting creates the milling paths that separate the finished PCB from the surrounding material. TraceFab can offset the board outline, divide the cut into depth passes and add bridge gaps that hold the PCB in place during machining.

1. Check the board outline

Confirm that the imported PCB has one valid, closed outer outline.
Check the board dimensions under File > Board Dimensions.
Make sure the outline is positioned correctly around the copper and drill data.
Make sure a suitable cylindrical milling tool is available in the Tool Library.

Correct the outline first: an open, duplicated or incorrect board outline can produce an incomplete or unsafe edge-cut path.

2. Open the Edge Cut window

Select Calc. Edge Cut on the toolbar, or open Manufacturing > Calc. Edge Cut.
Select the cylindrical milling tool that will be installed in the CNC machine.
Confirm that the physical tool diameter matches its Tool Library entry.

Tool Library : to calculate edge cuts, you must have a suitable tool ( Cylindrical Milling Tool ) in the Tool Library. If not available, please first create a cylindrical milling tool in : Parameters > Tool Library and add a suitable tool for edge cutting.

TraceFab Edge Cut Milling window with tool, depth, bridge-gap and inner-cut settings — Configure the outer board cut, depth passes, bridge gaps and optional inner cuts.

3. Configure the cut

Cut Depth and Max Depth Per Pass

Cut Depth is the final cutting depth. By default, TraceFab uses the PCB thickness plus a small overcut. Enable Max Depth Per Pass to divide the total depth into several passes and reduce the load on the tool.

Protect the wasteboard and machine: verify the PCB thickness, active Z zero, final cut depth and available wasteboard depth before machining. Disabling depth passes makes the tool cut the full depth in one pass.

Cut Side

Outside: keeps the external PCB dimensions and is the normal choice.
Center: places the tool centre on the imported outline.
Inside: moves the path inside the outline and reduces the finished dimensions.

4. Add bridge gaps

Bridge gaps leave short uncut tabs in the outer path so the PCB remains attached to the stock. Set a suitable Gap Size, choose the required North, East, South and West positions, and select Add Gaps. Select Preview again after changing any gap setting.

TraceFab preview showing automatically positioned bridge gaps in the PCB edge cut — Automatic gaps place tabs at the selected sides of the PCB.

TraceFab Edge Cut window while manually placing bridge gaps on the outer PCB path — Use Draw Gaps to place a tab near a chosen point on the outer path.

Manual gap placement

Select Reset and clear unwanted automatic gap directions.
Select Preview, then Draw Gaps.
Left-click near the outer edge-cut path to add each gap.
Disable Draw Gaps when placement is complete.

Keep the PCB supported: use enough bridge gaps to prevent the board from moving when the final perimeter pass completes. Keep tabs clear of clamps and important finished edges.

5. Include inner cuts when required

Enable Include PCB Inner Cuts when the PCB contains internal routed openings. Select a separate cylindrical tool if required. The cutter must physically fit inside every enabled opening.

Check tool fit: an inner-cut tool that is too large cannot reproduce the opening and may result in an invalid inner cut.

6. Preview, calculate and review

Select Preview.
Check that the outer path is continuous and follows the intended Cut Side.
Check every bridge gap and optional inner cut.
Select Calculate when the result is correct.

Review checklist

The outer path is a complete closed loop.
The finished dimensions match the selected Cut Side.
Bridge gaps are visible and strong enough to hold the PCB.
Every inner cut is visible and the selected tool fits.
The tool, final depth and depth per pass are correct.

Edge cutting is now prepared. The calculated outer and optional inner-cut operations become available in the Manufacturing window. Place the final outer edge cut near the end of the manufacturing sequence. Calculate does not generate G-code.