MEGA CORE XY 3D PRINTER

Primary Goal: Print large structural robot parts in optimal orientations while maintaining:

• Dimensional accuracy for robotic assembly fit

• Surface finish quality for minimal post-processing

• Speed to enable rapid design iteration

Key Challenge: Standard hobby printers either lacked build volume or couldn't maintain accuracy at necessary speeds for structural components.

Structural Design Philosophy:

Departed from typical maker approach of 3D-printed frame components. Instead, specified machined aluminum and waterjet-cut steel plates to achieve:

• Minimal flex under high acceleration

• Tight tolerance assembly

• Long-term dimensional stability

• Professional-grade performance

Motion System:

• Precision linear rails (low friction, high load capacity)

• Ball screws on Z-axis (vs lead screws) for accuracy

• High-quality stepper motors selected for torque/speed

• Belt tensioning system for CoreXY kinematics

Thermal Management:

• Fully heated build chamber (printing engineering plastics)

• Heated filament path (moisture management)

• Isolated electronics enclosure (thermal protection)

• High-power heated bed (large thermal mass)

Advanced Features:

• Dual Bowden extruders (multi-material/support)

• Filament pre-heater (improve layer adhesion)

• Separate electronics bay (extend component life)

• Enclosed design (temperature stability)

Final Cost Estimate: ~$5,000

The Math:

• Machined frame components: $1,200

• Linear motion (rails, screws, bearings): $800

• Electronics and motors: $600

• Heated chamber system: $500

• Dual extruder setup: $400

• Miscellaneous (belts, fasteners, etc.): $500

• Assembly time: 40+ hours

The Reality Check:

For $5,000, I could:

• Buy two high-quality 3D printers

• Outsource large prints to companies if needed.

• Purchase multiple Ender-3/Ender-5/CR-10 and adjust part orientation

The performance gain vs cost didn't justify building.

Decision: File away design, move forward with larger budget friendly printing.

Lessons Learned

1. Commercial vs Custom Trade-offs

• Custom builds make sense when:

  • Commercial options don't exist

  • Unique requirements justify cost

  • Learning is the primary goal

  • Budget isn't constrained

• They don't make sense when:

  • Commercial options are "good enough"

  • Custom costs 3-5x more

  • Time is limited

  • The tool isn't the end goal

2. Opportunity Cost

• $5,000 and 40 hours building a printer meant:

  • Less money for robot actuators, sensors, controls

  • Less time on actual research

  • Lower priority work taking resources from higher priority work

Sometimes the best engineering decision is not building something.

Value of Concept Work

While never built, this design exercise provided:

• Deep understanding of CoreXY kinematics in 3D printing systems

• Experience with precision motion system design

• Cost estimation and BOM development practice

• Insight into commercial printer trade-offs

• Material for teaching DFM principles (what NOT to do)

Current Approach

Instead of building the Mega CoreXY Printer:

• Bought Ender - 3, Ender - 5, and CR-10 Creality 3D-Printers

• Designed PANDORA parts to fit within available build volumes

• Accepted slower print speeds with multi-day builds

• Focused budget on robot components, not tooling

Result: PANDORA parts were completed successfully without $5,000 printer investment.