/sscara

Small size 3d printer with SCARA based mechanics

Primary LanguageOpenSCAD

sscara

Small size 3d printer with SCARA based mechanics

Current Status: V3 - DONE

V3 Videos: https://youtu.be/qMoxgC5KaG4 https://youtu.be/IasEUXix5cc https://youtu.be/JhraS_r1Fzk

History:

  • 01.05.2016 - V3 - DONE
  • 28.01.2016 - V3 - WIP
  • 11.01.2016 - V2 - DONE (fail)
  • 05.01.2016 - V2 - Final tests
  • 28.07.2015 - V2 - WIP
  • 27.07.2015 - V1 - DONE
  • 27.04.2015 - V1 - WIP

Precision: WIP XY: 0.03 mm with 32 microsteps at 150 mm radius from axes center. (chord length c=2Rsin(alpha/2), alpha = 1.8/5/32 (stepper/gearratio/nummicrosteps); Z: GT2 16 teeth pulley with 32 microsteps - 5 μm (http://reprap.org/wiki/Step_rates)

Other features:

  • Noiseless

Hardware:

  • 4 Nema17 (24mm length shaft)
  • Ramps 1.4
  • 4 drv8825 (drv8825 is better due to 1/32 microstepping)
  • External power supply 5A (without Heated bed)
  • Heated bed ????? depends on (but seems like require in 4x time less current than MK2B - because of 4 times lower area)
  • 3 small (20x11x7mm) end stoppers Optional:
  • HC-05 bluetooth module (i am happy with it, even firmware flashing done via bluetooth)

Marlin Firmware modifications:

  • FIVE_BAR define added for SCARA define
  • added M450 - xyz min limits
  • added M451 - xyz max limits
  • added M452 - xyz home pos
  • added M370 X#Angle Y#Angle
  • G2/G3 commands support
  • Fixed math for pure SCARA (2 arms)

Materials:

  • ~1.5 meters(2m max) - GT2 timing belt 6mm(width)
  • 3 - GT2 16 teeth pulleys (ID=5mm)
  • 4 - Nema17 (24mm shaft length) (39 mm Nema17 might be used for xy)
  • 4 - 625 bearings (ID-5mm,OD-16mm,H-5mm)
  • 2 - 608 bearings (ID-8mm,OD-22mm,H-7mm)
  • 21 - 623 bearings (ID-3mm,OD-10mm,H-4mm)
  • 1 - aluminium tube (ID-6mm,OD-8mm) - 350mm max
  • 1 - m5 threaded rod - 500mm max
  • 1 - m3 threaded rod - 2 meters max
  • m3 bolts and nuts
  • m5 nuts
  • ABS filament to print parts

SCAD:

  • use drawArray = [] to draw everything or drawArray=[1,2,3] for parts
  • use printLayout to control parts/subparts layout (0 for design, 1 for export) (Some parts need to be rotated to 180 Y) (WIP)
  • NemaSize - tweak nema len, NemaLengthMedium,NemaLengthShort,NemaLengthLong

Slicer:

  • Slic3r
  • ABS - 0.4mm nozzle, setup is described in scad file for each part

Included Software:

Reachability visualizer

Calibration Guide: Enable EEPROM in you firmware.

Initial rough calibration:

  • G28 goto home
  • Steps Per Units - M92 X## Y## where ## is a stepperUnitsPerRevolutiondriverMicrosteppinggearboxration/360, (Nema17 1.8deg with drv8825 1/32), v1 = 200325/360 = 88.888, v2 = 142.222

XY init calibration:

  • G28 goto home
  • M452 X#xx Y#yy - where #xx and #yy is a measured distance from nozzle to the axis center (xx should negative, +/-1 mm is enought)

NOTE: Put your min max software limits a little bit bigger (i used 3 cm) (use M450 and M451), this is required for the next steps.

XY precise calibration:

Precise Steps Per Units calibration:

  • G28 goto home
  • M370 X0+#xx Y-90+#yy // move arms to 90 and 180 degrees, #xx and #yy is an extra angle to move arms exactly to 90 and 180 degrees
  • M370 X90+#xx Y0+#yy // #xx and #yy from prev step
  • if your arms not exacly 0 and 90 degrees use M92 X## Y## +/- values until all sequence above will get 0 and 90 degrees
  • Repeat a few times until you get 90 and 180 degrees exactly
  • M500 to save data to EEPROM

Precise home offsets calibration:

  • G28 goto home
  • M370 X0 Y-90 // move arms to 0 and -90 degrees
  • M206 X## Y## (where X## Y## is a angular distance to 90 and 180, this is homing offsets in angles, can be used from prev steps)
  • Repeat a few times until you get 90 and 180 degrees exactly
  • M500 to save data to EEPROM

Z calibration

  • G28 Z
  • Ajust platform height

Development blog - https://3dgems.blogspot.com