CNC Circuit Mill/V2 Design Rationale: Difference between revisions

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The function of the frame is to move a part of the frame in 3 dimensions (relative to its base). For a good frame, we look for:
The function of the frame is to move a part of the frame in 3 dimensions (relative to its base). For a good frame, we look for:


*'''Precision'''
*[http://en.wikipedia.org/wiki/Accuracy_and_precision Precision]


*'''Rigidity'''
*[http://en.wikipedia.org/wiki/Stiffness Rigidity]


*'''Speed'''
*[http://en.wikipedia.org/wiki/Speed Speed]


*'''Torque'''
*[http://en.wikipedia.org/wiki/Force Force]




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=Major Frame Type=
=Major Frame Type=


Revision as of 18:38, 16 May 2012

Frame

The function of the frame is to move a part of the frame in 3 dimensions (relative to its base). For a good frame, we look for:





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 uniform dimensions (40mm, 75mm)
  • 40mm to accommodate the mounting circles of leadscrew nuts.
  • 70mm to accommodate the mounting orientation of stepper motors.

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)
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