Slide 001: Print Execution — From G-code to First Layer¶
Slide Visual¶
Slide Overview¶
This slide walks students through the complete process of executing a print from the moment G-code leaves the slicer to achieving a successful first layer. The first layer is the single most important factor in print success — approximately 60-70% of all FDM print failures originate from first-layer issues.
Instruction Notes¶
G-code Transfer Methods¶
Once slicing is complete, the G-code must reach the printer: - SD/USB card: Most reliable method. Copy .gcode file to card, insert into printer. No network dependency. Recommended for critical or long prints. - USB cable (direct): Tethered connection from computer to printer. Risk: if the computer sleeps, crashes, or disconnects, the print stops immediately. - Network/WiFi: Printers with WiFi (Bambu Lab, Prusa MK4) or OctoPrint/Klipper interfaces accept uploads over the network. Convenient but dependent on network stability. - Cloud services: Bambu Cloud, OctoPrint remote. Allow monitoring from anywhere but add latency and require internet connectivity.
Printer Startup Sequence¶
A standard FDM printer executes this sequence at the start of every print: 1. Heating: Nozzle and bed heat to target temperatures simultaneously (1-5 minutes) 2. Homing: All axes move to their endstops to establish coordinate origin (X, Y, Z = 0,0,0) 3. Auto-bed leveling (if equipped): Probe measures bed surface at 9-49 points, creates compensation mesh 4. Z-offset application: Final nozzle-to-bed distance is set (critical for first layer) 5. Purge line/prime: Nozzle extrudes a line along the bed edge to prime the filament flow
Achieving a Perfect First Layer¶
The ideal first layer exhibits these characteristics: - Lines are slightly flattened (not round, not transparent) - Adjacent lines touch with no gaps between them - Uniform width across the entire first layer - Material sticks to the bed without excessive squish
Z-offset adjustment guide:
| Observation | Z-Offset Action | Increment |
|---|---|---|
| Lines round, gaps visible | Decrease (lower nozzle) | -0.02mm |
| Lines flat but have small gaps | Decrease slightly | -0.01mm |
| Lines flat, touching, slight ridge | Perfect — no change | 0 |
| Lines very flat, transparent | Increase (raise nozzle) | +0.02mm |
| Nozzle scraping/dragging | Increase significantly | +0.05mm |
Live Adjustment During First Layer¶
Most modern printers allow real-time Z-offset adjustment during the first layer. This is the most effective way to dial in first-layer quality. Make small adjustments (0.01-0.02mm) and observe the result over the next few lines before adjusting again.
Key Talking Points¶
- Always watch the first 2-3 layers — this is your quality gate for the entire print
- The perfect first layer looks like slightly overlapping flat ribbons, not round spaghetti and not transparent film
- Live Z-offset adjustment during the first layer is a critical hands-on skill every operator must develop
Learning Objectives (Concept Check)¶
- [ ] Students can describe the printer startup sequence from heating through first layer
- [ ] Students can identify good vs. bad first layer characteristics
- [ ] Students can perform live Z-offset adjustments to achieve proper first-layer adhesion
Last Updated: 2026-03-19