Initial copy stand design

README.md

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+# Copy Stand Base Plate
+
+A parametric, 3D-printed copy-stand base sized for a Bambu Lab X2D and designed
+around a Lobster Holder V2.1 on its CS-Lite. The base uses a removable 2020
+extrusion socket, adjustable 1/4-20 feet, and an optical-breadboard-style
+1-inch grid of heat-set inserts.
+
+The structural parts are intended for black ASA. Grid lines are flush blue ASA
+inlays printed against a textured build plate.
+
+## Coordinate system and principal dimensions
+
+- Base: 203.2 x 248 x 15 mm, with 12.7 mm corner radii.
+- The grid origin is Y=0 and positive Y runs toward the operator. The socket's
+  straight front reference face is Y=12.7 mm (0.5 inch), halfway between the
+  origin and the first insert row.
+- The 8 x 8 insert array has 25.4 mm spacing. Its rows are Y=25.4 through
+  Y=203.2 mm relative to the socket datum.
+- A blue Y=0 datum line continues beneath the socket, leaving aligned visible
+  segments on both sides.
+- The removable socket captures 50 mm of a nominal 20 x 20 mm extrusion.
+- Its 110 x 38.7 x 10 mm flange reaches from the rear plate edge to the
+  half-inch reference face. The column is shifted forward to improve the
+  overturning load path and reduce the camera arm's required overhang.
+- The two outside inserts in the front grid row also mount the front leveling
+  feet. They cannot accept top-side accessories while the feet are installed.
+
+## Hardware
+
+| Qty | Item | Relevant dimensions |
+| ---: | --- | --- |
+| 70 | [McMaster 97171A240 brass 1/4-20 heat-set insert](https://www.mcmaster.com/97171A240/) | 9.525 mm body, 12.7 mm flange, 1.27 mm flange thickness, 8.026 mm maximum hole |
+| 4 | [1/4-20 adjustable foot](https://www.amazon.com/dp/B095PDSNPM) | 19 mm pad diameter, 8.5 mm pad height, 17.8 mm stud |
+| 4 | [Knurled 1/4-20 locking nut](https://www.amazon.com/dp/B0GQSX98V4) | 24.4 mm OD, 6 mm thick |
+| 1 | [European-style 2020 T-slot extrusion](https://www.amazon.com/dp/B08Y8N7FD1) | 20 x 20 x 400 mm, 6 mm slots |
+| 4 | 1/4-20 x 1-inch socket-head screws | Socket flange to base |
+| 4 | Black 1/4-inch flat washers, specified as 0.7 inch (17.78 mm) OD | Load distribution beneath socket screw heads; measure thickness before assembly |
+| 4 | M5 x 10 mm socket-head screws and European 2020 T-nuts | Extrusion clamp; verify screw length against the selected T-nut |
+
+The four feet use four of the listed inserts: two dedicated rear inserts and
+the two shared front grid inserts. Four more dedicated inserts secure the
+socket. The remaining 64 inserts make up the complete grid.
+
+The McMaster drawing requires at least 0.530 inch (13.46 mm) of material. Every
+insert boss in this design is 15 mm tall, including all four socket-mounting
+bosses. The 52.5 x 22.5 mm locating slot passes through the base between those
+bosses, so it does not reduce their thickness. Inserts install from the open
+underside with their flange flush against the boss. The 1.35 mm flange seat and
+9.525 mm body leave a 4.125 mm screw-clearance tunnel below the clean 6.8 mm
+opening in the working surface.
+
+## Build
+
+Requirements: OpenSCAD 2021.01 or later, Ruby, and Python 3.
+
+```bash
+ruby build.rb
+```
+
+The build is incremental. Run `REBUILD=1 ruby build.rb` to regenerate every
+component after changing geometry parameters.
+
+Generated files are placed under `exports/3mf` and `exports/stl`. The primary
+files are:
+
+- `base_multicolor.3mf`: aligned black base and blue inlay meshes, assigned to
+  filaments 1 and 2.
+- `socket.3mf`: removable black socket and gusset assembly.
+- `coupon_multicolor.3mf`: two-piece insert, rail-clearance, through-key-fit,
+  and line calibration coupon.
+- `coupon_key.3mf`: standalone full-size tongue gauge from the two-piece
+  coupon.
+
+The portable multipart files intentionally do not embed a printer or process
+profile. The individual aligned meshes and single-color fallbacks are retained
+alongside them.
+
+## Calibrate before the full base
+
+Print `coupon_multicolor.3mf` in the intended ASA, face down on the intended
+textured plate. It produces a main coupon and a separate full-size tongue
+gauge. From left to right, the insert pilots are 7.70, 7.85, 8.00, 8.15, and
+8.30 mm. The four rail gauges are 20.0, 20.1, 20.2, and 20.3 mm. Each is a
+four-wall collar with the production 6 mm side walls, 2.7 mm end walls, and
+full 50 mm engagement depth. External gussets and M5 holes are omitted because
+they do not define the rail-fit surfaces. The coupon also
+contains the production-width blue line and a 6 mm-deep production-size
+52.5 x 22.5 mm through-slot. The separate 52 x 22 x 6 mm tongue prints in the
+same orientation as the socket tongue and has a support-free stop shoulder and
+vertical grip for insertion and removal. Verify that the slot is visibly open,
+with no first-layer membrane, before testing the fit.
+
+The production model defaults to the physically calibrated 8.10 mm insert
+pilot and 20.1 mm rail cavity. These values were selected from an ASA coupon:
+the 20.1 mm collar accepted the fully cooled rail through all 50 mm by hand
+without objectionable play, and the 8.10 mm pilot provided the preferred
+insert fit. The rectangular tongue and through-slot also passed the physical
+fit test, so their dimensions remain unchanged. For another printer, material,
+or process, select the smallest rail gauge that fits without forcing and use
+the insert pilot that gives the required installation grip. Change
+`insert_pilot_diameter` or `rail_clearance` at the top of `copy_stand.scad`,
+then rebuild. The 8.30 mm coupon remains a diagnostic oversize option;
+McMaster specifies 8.026 mm as the maximum nominal hole diameter, while this
+design's 8.10 mm production value reflects the tested print process.
+
+## Bambu Studio setup
+
+1. Open `base_multicolor.3mf` as one multipart object.
+2. Assign black ASA to Filament 1 and blue ASA to Filament 2.
+3. Keep the 248 mm dimension along the printer's Y axis and place the base to
+   one side. Its 203.2 mm X width leaves about 52.8 mm for a nominal 35 x 35 mm
+   prime tower and clearance.
+4. Confirm the tower and any brim fit in Preview before printing.
+5. Print the base face down. No support is designed into the base, socket, or
+   coupon.
+
+The coupon occupies approximately 228 x 110 x 53.2 mm including its separate
+tongue and full-depth rail collars. Orient its 228 mm dimension along Y to
+leave ample X space for the prime tower.
+
+A 0.4 mm nozzle and 0.20 mm layers are the compatibility target. Use at least
+six walls, six top and bottom layers, and 40-50% gyroid or cubic infill for the
+socket. Use at least four walls for the base, suitable ASA bed adhesion, a
+fully heat-soaked enclosure, and conservative cooling. The modeled open cells
+provide the base structure; sparse slicer infill is not relied on there.
+
+## Assembly
+
+1. Heat-set the inserts from the underside. Stop when each brass flange is
+   flush with its counterbore; do not pull it toward the textured top surface.
+2. Thread the leveling feet through their locking nuts and into the two rear
+   foot inserts and two outer inserts of the front grid row.
+3. Lower the socket's 52 x 22 x 6 mm tongue into the base's through-slot, then
+   fasten the flange with four 0.7-inch OD washers and four 1/4-20 x 1-inch
+   screws. The screws provide clamping and vertical retention; the tongue
+   provides repeatable X/Y location and carries lateral shear. With a washer
+   thickness `t` in millimeters, nominal insert engagement is
+   `11.275 - t` mm, limited by the insert's 9.525 mm threaded length.
+4. Preload two T-nuts in each side slot of the extrusion. Lower the extrusion
+   to the socket floor and fasten it through the four M5 clamp holes.
+5. Level the base, then tighten each knurled locking nut against its insert
+   flange.
+
+The Lobster/CS-Lite locating fixture, Arca rail, camera carriage, and camera
+alignment accessories are deliberately deferred. They can attach to the grid
+without changing this base.
+
+The socket's broad side buttresses stop before the four base screws. Vertical
+19 mm washer and tool envelopes preserve access above those screws, and 14 mm
+horizontal tunnels provide driver access to the M5 rail clamps without
+sacrificing the collar wall around the T-slot extrusion. The 19 mm fore/aft
+screw-row spacing and shallower side buttresses improve overturning and
+torsional resistance compared with the compact first revision.
+
+Before mounting a camera, proof-test the assembled stand with a dummy load at
+the maximum working overhang. Under the normal payload, target less than 1 mm
+of rail-tip motion. After 24 hours at twice the intended payload, require no
+cracking, washer embedment, or loose fasteners and less than 0.25 mm permanent
+rail-tip displacement after unloading.