8.7 Where it stands
Yesterday this was a portable monitor, a spare mini PC and a printer. Now there is a designed and checked range: one hub on the monitor's back that holds the PC, and four supports it docks into. Nothing beyond the two gauges has been printed yet.
The range
| E1 Arc | E2 Column | E3 Sail | E4 Wall | |
|---|---|---|---|---|
| Weakest push to tip | 6.2 N | 5.1 N | 6.4 N | Wall mount: 6.8 N pull on the top screw |
| Screen lean change under its own weight | 0.004° | 0.001° | under 0.001° | 0.005° |
| Top edge sideways under 5 N | 1.05 mm | 1.2 mm | 0.6 mm | 1.0 mm |
| Whole device: print time, PLA | 9 h 47 min, 398 g | 8 h 58 min, 357 g | 9 h 55 min, 408 g | 7 h 6 min, 267 g |
Each desk device adds about 10 g of TPU for its pad ring and cable clip. All figures assume a 0.8 kg monitor.
For scale, the same method gave B2, the stand I nearly built in round 2, a lean change of 0.87° and a weakest push to tip of 1.6 N.
What changed between versions
| Stand v1 (B2) | Stand v2 | Stand v3 (E2) | |
|---|---|---|---|
| Layout | Screen on a band round the PC | PC behind the screen, one spine | Hub on the screen, a fin under the centre of gravity |
| Largest constant moment | 1.72 N m | 0.44 N m | 0.21 N m |
| Lean change | 0.87° | 0.035° | 0.001° |
| Weakest push to tip | 1.6 N | 3.7 N | 5.1 N |
| Joints | Not designed | Laps, inserts, shoulder screws | Dock with bearing faces, pins that only lock |
The gains came from layout, not from thicker plastic: put the support under the load, make the beam bend across its depth, and put mass low and central.
What the process taught
- Gauge before you build. Two 4 g prints settled the screw depth for every mount and showed that the PC's photo-measured inserts were slightly off.
- A check proves only what it tests. Fused solids hid missing joints. A valid solid hid a hole the slicer found. A wrong cutting plane gave 18 MPa. A self-crossing offset gave six times the area. A STEP file lost 36% of a fin, and the slicer quietly repaired an open mesh. Each one was found by adding a check against something known.
- Orientation is a design decision. Choose how a part prints first. The fins, the inserts and the bridges all follow from it.
- Creep, not strength, governs PLA furniture. Stresses stay under 1.5 MPa everywhere. The lever is the enemy.
- Self-restoring is a number. , on every edge, with the edge where the pads actually touch.
- Fasteners locate; faces bear.
- Work in parallel. The design work and this blog ran in two agent sessions at the same time, one building and one recording, which kept the record current as the design moved.
Next
These steps need me and the real hardware:
- Weigh the monitor. Every balance figure assumes 0.8 kg.
- Print the dock coupon: about an hour and 26 g. Check the slide, the shoulder seat and the pin.
- Choose the first device. The case for E2 is in 8.2: half E1's moment, the quickest print, and the cheapest full test of the shared hub. E1 is now a stiff choice for the reference look. E4 suits a wall.
- Take calliper values for the PC's inserts and put them in its model.
- Print the device, then measure the PC's temperature under load inside the shell.
The blog continues from there.