CNC Circuit Mill/V2 Design Rationale
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Major Frame Type
- Selected - Mobile gantry design (XYZ all linked) allows tremendous scaling potential.
- Mobile bed (X alone, YZ linked) requires a greater non-axis frame to support both X and YZ; scales ineffectively.
Minor Frame Type
- Selected - Blocks on plate (Non-axis frame is a plate; X axis begins with 4 blocks on this plate)
Frame Material
- Selected - 6061 Aluminum Alloy for rigidity, ease of machinability, and accessibility
Axis Drive
- Selected - Stepper motors provide high resolution in a simple open-loop system
- AC or DC motors with encoders necessitate complex closed-loop control systems
Spindle Drive
- Selected - Outrunner Brushless DC Motor has maintenance-free operation, over 90% efficiency, commutator-free long lifetime, precision speed control possible, quiet operation, more torque than inrunners
- Brushed DC Motors require regular maintenance, short lifetimes, noisy operation
http://www.youtube.com/watch?v=fPLdHeRQp_w
http://www.rcgroups.com/forums/showthread.php?t=1118773
http://www.tcrconline.com/documents/electric%20flight.pdf
Rotary-to-Linear
- Selected - Leadscrew and Nut for high velocity ratio and lifetime operation
- Belts stretch and have low velocity ratio
Axis Supports
- Selected - Precision Shafts for ease of manufacturing and direct mounting
- Precision V-Rails
- Precision Extrusions
Block Dimensions
- 2 dimensions (40mm, 75mm)
Sleeve Bearing Mount Dimensions
- Mount hole diameter (18mm)
- Mount circle diameter (32mm)
Leadscrew Nut Mount Dimensions
- Mount hole diameter (12.7mm)
- Mount circle diameter (19.05mm)
Stepper Motor Mount Dimensions
- Mount square side length (31mm)
- Mount hole diameter (3mm)
- Center hole diameter (22mm)
Collar Dimensions
- Length (10mm)
- Outer diameter (25mm)
- Inner diameter (12mm)
- Setscrew (M5x0.8, Xmm Lg, 2.5mm drive)
Coupling Dimensions
- Length (30mm)
- Outer Dimensions (15mm)
- Inner Diameter (3mm OR 5mm OR 1/4" OR 1/8")
- Setscrew (M5x0.8, Xmm Lg, 2.5mm drive)