Slug-retention tab

kerfmaster pin list · Definitions

recordmixedStates what the code does today. Auditable against the code — this is the only type that can go stale.

Content last changed 2026-08-03 — computed from the item itself, not typed.

A slug-retention tab is a short length of an interior boundary deliberately left uncut, so the waste piece (the "slug") stays put instead of dropping through the bed or tipping up into the head.

Confirmed by Jordan, 2026-07-29, after it was measured out of the shop's own production NC for the novi sign: every one of the 90 interior boundaries stops a constant 0.0181" short of its own start point, and the outer profile closes exactly. The customer DXF contours are all closed, so this is added by the post — it is not inherited from the file.

Three holds, three purposes — do not conflate them

• Bridge (item 2b) — permanent. Holds an island into the finished part. Per-part, before nesting. Sized to hold.
• Tab (item 3a) — sacrificial. Holds the part into the surrounding sheet. Nest-stage. Sized to snap off easily.
• Slug-retention tab (this item) — sacrificial, and on the waste side. Holds the scrap so it doesn't drop. Post-stage, on interior boundaries only. Sized to hold a slug and then be punched out.

All three post the same way — a gap left in the cut path — and all three are sized for different goals. A lead or pierce must never land inside any of them.

Sizing

Answered by Jordan, 2026-07-29: it scales with material thickness, and the values will be defined in the tables. So this is the third width table alongside bridges (item 2b) and tabs (item 3a), with the same treatment — ships as defaults, lives in operator Preferences, editable per laser and per location.

Superseded by a real test cut, 2026-07-30 (Aristide) — see item 3b for the numbers. The headline: the driver is slug size and leverage, not thickness alone. The "0.30 × thickness" ratio is dead: 0.018" held on 0.060 material and held again on 0.125 material for small slugs, where a ratio would have demanded 0.037". A big slug on the same 0.125 sheet needed 0.033", and a slug under 3/4" needed no tab at all. So the table is keyed on material × thickness and slug size.

Failure is not cosmetic: an undersized tab lets the slug drop early and the loose piece can hit the laser head. When a slug falls between two bands, round up.