4 Axis GPU-CNC

I am now converting a mill head (taken from my lathe

Updated photo - had to build a new case and earthing to stop noise mucking up axis positions.

Notes on building a CNC machine

TODO

• • Set backlash: http://www.cncexpo.com/MeasuringBacklash.aspx

Controller

Was: 4 Axis CNC kit http://www.techlf.com/cnc4bu_kit.php3

Now moving to http://www.planet-cnc.com/

• • CNC USB controller software license

  • CNC USB controller Mk2 (9 Axis)

  • Connectors for CNC USB controller

  • MotorDriver 2.5A x 4

Mill Head

From Lathe

• • Drilling Capacity = 13mm

  • End Mill Capacity = 13mm

  • Face Mill Capacity = 50mm

  • Spindle Taper = MT2

  • Spindle Stroke = 50mm

  • Head Tilt = +/- 90 degrees

  • Number of Spindle Speeds = variable

  • Range of Spendle Speeds = 50~2250RPM

  • T-Slot Size = 8mm

  • Motor = 500W, 1Ph, 230V

  • Hand Wheel Graduation 1mm (= 1mm x 50 per revolution = 50mm per revolution)

Stepper motors

23H076-4

• • 1.8 deg. (200 steps per revolution)

  • bipolar

  • 4 wires

  • 3 Amp / Phase

  • 1.8 Nm

  • Nema 23

  • shaft 6.2mm d

Compound Table

From HAFCO

• • Table Size 155 x 470mm

  • Longitudinal Travel 290mm (limited to 240mm due to bits in the way)

  • Cross Travel 177mm (limited to 110mm due to bits in the way)

  • Tee Slots 2 x 1/2"

  • Height 130mm (travel from set position 46mm)

  • Hand Wheel Graduation 0.001" (= 0.0254mm x 100 per revolution = 2.54mm per revolution)

  • Weight (nett) 28kg

Timing Pulley config

• • X = x10 (Stepper) connected to x20 (hand wheel): 1 revolution = 2.54mm/2 = 1.27mm

  • Y = x10 (Stepper) connected to x20 (hand wheel): 1 revolution = 2.54mm/2 = 1.27mm

  • Z = x10 (Stepper) connected to X30 (hand wheel): 1 revolution = 50mm/3 = 16.666667mm

Purchased

• • T5 - 10 Tooth - 10mm Timing Belt Pulley x 4

  • T5 - 20 Tooth - 10mm Timing Belt Pulley x 4

  • T5 - 30 Tooth - 10mm Timing Belt Pulley x 1

  • T5 - 50 Tooth - 10mm Timing Belt x 2

  • T5 - 80 Tooth - 10mm Timing Belt x 2

  • T5 - 60 Tooth - 10mm Timing Belt x 1

Resulting Axis Config

• • X = 1.27mm(revolution) / 200(steps) = 0.00635 per step = 157.48 per mm

  • Y = 1.27mm(revolution) / 200(steps) = 0.00635 per step = 157.48 per mm

  • Z = 16.666667mm(revolution) / 200(steps) = 0.083333 per step = (12 per mm x16 microsteps) = 192.00 per mm