How do I cut a batch of ornaments from thin stock without parts coming loose?

What the project is

Ornaments are small, light parts cut from thin sheet, which is the hardest thing to hold on a router. The method that works is: engrave everything first, then cut outlines almost through, leaving a paper-thin skin or tabs so the sheet stays in one piece.

Steps

1. Stock. A published walkthrough uses 1/8 inch Baltic birch. Measure the real thickness with calipers; the skin depends on it.
2. Vectors. Import or trace the shape and reduce it to one closed outline plus one circle for the hanger hole. Size the ornament (the example is 3 by 3.6 inches).
3. Nest. Select the ornament and open Nest Parts. Enter the Tool Dia. of the profiling bit, a Clearance, and the Number of Copies, then Preview. Minimum spacing is Tool Dia. plus Clearance. A hole inside the outline is treated as part of the same part and moves with it. For plywood with a face grain you care about, limit rotation.
4. Lettering first. V-carve names or dates while the sheet is whole. On thin stock check Flat Depth; the walkthrough reports 0.1 inch working on 1/8 inch material.
5. Hanging holes. Drilling Toolpath on the hole circles, through the sheet.
6. Outlines last. Profile with a 1/8 inch bit. Either set Cut Depth 0.005 inch less than the measured thickness to leave a skin (onion skinning), or cut through and add tabs. Create 3D Tabs lets the cutter ramp over each tab instead of stopping.
7. Release. With a skin, sand the back with coarse paper (80 grit in the example) until the ornaments drop free.

Workholding

The skin only works if the sheet is flat everywhere. Use many hold-downs, or tape and glue across the whole back. A bowed sheet gets cut through in the high spots and left thick in the low ones.

Pro tips

• Leave a generous Border Gap so hold-downs have somewhere to sit.
• A smaller bit means tighter nesting and thinner tabs to clean up.
• See the entries on holding small parts and on tabs for more options.