OPJAW

Zero-Point Clamping Plates

Upload a STEP file. Get a zero-point clamping plate — conforming nest pocket on top, 52 mm pull stud interface on bottom — as a verified STEP solid.

Generated zero-point plate for a heat sink — rectangular conforming pocket with four pull stud holes on 52 mm bolt circle

Specifications

Material Aluminum 6061-T6
Plate thickness 30.0 mm
Nest pocket depth 3.0 mm
Part clearance 0.2 mm per side
Plate margin 40.0 mm per side
Tool radius 3.175 mm (1/4″ endmill)
Corner fillet 3.0 mm
Max plate size 350 × 350 mm
Surface finish as-machined

52 mm clamping interface

Bolt circle 52.0 mm
Pull studs 4 at 90° spacing (45° start)
Through-bore 12.5 mm
Counterbore 20.0 mm dia × 10.0 mm deep
Locating pin 8.0 mm dia at 36.0 mm offset

OPJAW generates the hole geometry. You supply the pull studs — centering, compensating, and clamping — to match your receiver. The 96 mm bolt circle is not currently supported.

When to use a zero-point plate

Zero-point plates lock onto spring-loaded receivers via pull studs. Pallet swap takes seconds — you build the next setup offline while the spindle cuts the current job. The tradeoff is 30 mm of Z-height and a mechanical joint between your part and the table.

If you change setups more than twice a shift, the time wins. If you run one part number for a week, a fixture plate bolted directly to the table wins on rigidity.

The other advantage is datum continuity. The same plate with the same studs locks into receivers on the mill, the CMM, the EDM, and the grinder. The part datum does not move between machines because the receiver defines it. Fixture plates do not transfer — they bolt to one table.

The 52 mm bolt circle limits part footprint. If the conforming pocket extends far enough to intersect the pull stud holes, the system rejects the part for zero-point and scores fixture plates instead. Of the 20 parts in the stress test suite, 6 fit the 52 mm interface.

Zero-Point Plate Fixture Plate 6″ Vise Jaws
Plate thickness 30.0 mm 25.0 mm 50.8 mm (jaw height)
Clearance 0.2 mm / side 0.2 mm / side 0.15 mm / side
Nest / pocket depth 3.0 mm 3.0 mm 12.7 mm
Clamping method Pull studs (52 mm BC) Bolted to table Vise jaw grip
Setup time seconds (pallet swap) 15–45 min 5–15 min
Requires flat bottom yes yes no
Max part envelope ~120 mm footprint ~270 mm footprint 152.4 mm jaw width
Best for high-mix, multi-machine large parts, long runs compact parts

Example output

Generated from STEP files in the stress test suite. Plate dimensions scale to the part footprint. Tool radius compensation rounds internal pocket corners to the cutter diameter.

Zero-point plate for heat sink — silhouette pocket with fin channel detail

Heat Sink

Plate 102.3 × 94.5 × 30.0 mm
Pocket silhouette
Zero-point plate for strap hinge — elongated silhouette pocket

Strap Hinge

Plate 132.0 × 92.0 × 30.0 mm
Pocket silhouette
Zero-point plate for terminal block — bounding box fallback pocket

Terminal Block

Plate 92.0 × 127.0 × 30.0 mm
Pocket bbox fallback

What disqualifies a part

01_pillow_block — rejected

Pull stud #1 at (18.4, 18.4) intersects nest pocket. Part footprint exceeds the 52 mm bolt circle clearance. Use a fixture plate instead — same nest pocket, no bolt circle constraint.

16_leveling_mount — rejected

No Z-aligned flat face for seating. Parts without a planar bottom cannot use zero-point plates or fixture plates. See how fixture generation works for how seating faces are selected.

14 of 20 test parts are rejected for zero-point — most because their footprint intersects the pull stud holes. The auto-selector scores all four strategies and recommends the best fit.

Verification

Every output is measured by the geometric oracle before download. Bounding box, volume, and plate thickness are checked against declared ranges. If a plate measures outside 30.0 ± 0.1 mm in Z, you get an error, not a file.