Prusa i3 Hephestos
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Release status: working
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Contents
- 1 Introduction
- 2 Gallery
- 3 Technical specifications
- 4 Changes with respect to other models Prusa i3
- 5 Printed Parts
- 6 Bill of Materials
- 7 Assembly Guide
- 7.1 Required tools not included in the BOM
- 7.2 Preparation before assembly
- 7.3 Axis assembly
- 7.3.1 X Axis
- 7.3.1.1 Bearing Assembly
- 7.3.1.2 Prepare the X Axis tensioner
- 7.3.1.3 Enter the X Axis tensioner
- 7.3.1.4 Assembly smooth rod bearings
- 7.3.1.5 Prepare the X Axis Endstop sensor
- 7.3.1.6 Introduce the X Axis Endstop sensor in the smooth rod
- 7.3.1.7 Assemble the smooth rod into the side parts
- 7.3.1.8 Mount the X Axis motor
- 7.3.1.9 Introduce the adjustment screw for the X Axis Endstop
- 7.3.1.10 Introduce the pulley on the X Axis motor
- 7.3.2 Z Axis
- 7.3.2.1 Couple the motor hold on the frame
- 7.3.2.2 Couple the Z motors
- 7.3.2.3 Attach the top tether of smooth rods
- 7.3.2.4 Prepare the Z Axis Endstop
- 7.3.2.5 Union X Axis with Z Axis: Insert threaded rods
- 7.3.2.6 Union X Axis with Z Axis: Introduce smooth rod
- 7.3.2.7 Union X Axis with Z Axis: Union with X Axis:
- 7.3.2.8 Union X Axis with Z Axis: Flexible coupling
- 7.3.2.9 Union X Axis with Z Axis: Z Axis Endstop
- 7.3.3 Y Axis
- 7.3.3.1 Preparation of M10 threaded rod
- 7.3.3.2 Preparation of smooth rods
- 7.3.3.3 Union of smooth rods with threaded rods
- 7.3.3.4 Secure with nuts
- 7.3.3.5 Secure with cable ties
- 7.3.3.6 Preparation of Y Axis tensioner
- 7.3.3.7 Preparation of Y Axis motor
- 7.3.3.8 Preparation of the M8 threaded rods - Part 1
- 7.3.3.9 Preparation of the M8 threaded rods - Part 2
- 7.3.3.10 Union of the rods
- 7.3.3.11 Secure the structure with nuts
- 7.3.3.12 Preparation of the aluminum base
- 7.3.3.13 Secure the base aluminum with cable ties
- 7.3.3.14 Prepare the Endstop of the base
- 7.3.3.15 Secure the Endstop at the base
- 7.3.3.16 Place the belt of the Axis Y
- 7.3.3.17 Tighten all nuts
- 7.3.3.18 Place the acrylic base
- 7.3.3.19 Prepare the Y Axis Endstop on the frame
- 7.3.3.20 Secure the Y Axis Endstop on the frame
- 7.3.3.21 Union Y Axis with the X and Z axes: Snap axes
- 7.3.3.22 Union Y Axis with the X and Z axes: Fit and tighten nuts
- 7.3.4 Extruder
- 7.3.4.1 Prepare the carriage
- 7.3.4.2 Place the carriage in the X axis
- 7.3.4.3 Secure the carriage with a flange
- 7.3.4.4 Place the belt on the X Axis
- 7.3.4.5 Screw the Extruder support
- 7.3.4.6 Place the extruder
- 7.3.4.7 Placing the blower nozzle and Hot end security
- 7.3.4.8 Place the glass on the base
- 7.3.5 Electronic
- 7.3.6 Tuck the wires in the X Axis chain stitch
- 7.3.1 X Axis
- 7.4 Printer settings
- 7.5 Hello world: Your first print
- 7.6 Annex
Introduction
Facilitate the installation and set-up of the printer.
- Prusa 3D printer Hephestos is an open source 3D printer designed and developed by the bq Department of Innovation and Robotics. Hephestos is based on the Prusa i3 and adds several improvements to other printers like PowerCode. Parts were developed by the RepRap community with modifications and new parts added by bq.
- This project has sought to offer a robust printer design, addressing many of the shortcomings of earlier designs such as end-stop positioning and wiring routing. We have placed particular emphasis on providing good documentation to facilitate its assembly.
- Where to buy
- bq Spain - (author) - free shipment - Leds & Chips Assembled - Portugal - Leds & Chips Portugal - Iniciativas 3D Spain - wi3d Print Spain - 3D Proditive Shop Spain - Simac Spain - Crea3D Italy - 3DPrinter Store Ch
Building Instructions Video (Youtube):
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Prusa i3: Unboxing video (Youtube):
<videoflash type="youtube">c_TUTrBQ2XU</videoflash>
Gallery
Technical specifications
Dimensions
- -Printer Dimensions: 460(X) x 370(Y) x 510 mm(Z without roll) 583 mm(Z with roll )
- -Print Area Dimensions: 215(X) x 210(Y) x 180 mm(Z)
- -Box Dimensions: 400(X) x 400(Y) x 250 mm(Z)
Mechanical Construction
- -Powder coated aluminium frame & base
- -Smooth chrome rods for bearing carriages X, Y, Z
- -Linear ball bearing LM8UU for X, Y, Z
- -Axial ball bearing pulleys B623ZZ for X, Y
- -Igus cable carrier chain
- -Flexible aluminium coupling for threaded rods of Z Axis
- -4 point print base levelling system with cushioning
- -Quick change system for print base with Clips
- -Brushless Fans with axial ball bearings.
Print resolution
- -Very high: 60 microns
- -High 100 microns
- -Medium 200 microns
- -Low 300 microns
Extruder Mechanics
- -Custom extruder design (Witbox)
- -0.4mm nozzle
- -Fin heatsinks with axial fan
- -Part cooling nozzle
Print speed
- -Recommended speed: 50 mm / s
- -Maximum recommended speed: 80 mm / s
Electronics
- Any RepRap electronics conforming to RepRap Interface Standard RIS 1.
- -LCD with rotary encoder and push-button navigation
- -Cold glass base (size:220 x 220 x 3 mm)
- -Power supply: 220 AC 12 DC 100W
- -Thermistor 100k extruder
- -Heating element: 12V 40W
Software
- -Firmware derivative Marlin
- -Recommended environment: Cura Software
- -Supported Files:. Gcode
- -OS supported:
- Windows XP and above
- Mac OS X and above
- Linux
Communications
- -Standard SD card reader
- -USB Port Type B
Materials
- PLA Filament 1.75-mm
Changes with respect to other models Prusa i3
- Limit switch clamping:
- Designed by the department specifically for this model.
- Limit switch clamping:
- Belt tensioners
- Tensioner X axis identical to the Power Code. Tensioner Axis Ydownloaded from Thingiverse. http://www.thingiverse.com/thing:68185
- Support for RAMPS
- Designed by the department specifically for this model. Includes three anchors to collect the wires on one side through the use of a cable tie. Guiding the cables ensures the Driver heatsinks are not covered.
- Support LCD
- Designed by the department specifically for this model. The design has been inspired by http://www.thingiverse.com/thing:121640
- Support Fan
- Designed by the department specifically for this model.
- Cable Carrier
- Parts modified to include the cable carrier on all axis, avoiding pinching, cuts and catching the cable during axis movement.
- Power supply
- Laptop power supply
- Extruder
- Witbox extruder.
- Frame
- Official Prusa design modified. A recess has been added to the Y axis area to prevent friction which previously existed during the levelling of the base plate caused by the screw protruding. File:Frame&base Hephestos.dxf.zip
- Printing volume
- 215x210x180 mm
Printed Parts
Thingiverse page: http://www.thingiverse.com/thing:371842
Own designs
X Axis cable carrier coupling
Part Downloads File:Acople cadeneta Eje X.zip
Mechanical Endstop clamping X axis
Part Downloads
File:EjeX final de carrera.zip
Mechanical Endstop clamping Y axis
Parts Downloads File:EjeY final carrera marco.zip File:EjeY final carrera base.zip
Mechanical Endstop clamping Z axis
Part Downloads File:Eje Z final carrera.zip
Hot End security
Part Downloads File:Seguridad Hot end.zip
Tools
Part Downloads File:Llave fija impresa archivos.zip
LCD support
Part Downloads File:Soporte lcd.stl File:Bisagra lcd.stl
Fan support
Part Downloads File:Soporte ventilador archivos.zip
Filament holder
Modified
X Axis carriage
- The following changes have been made to the original carriage:
- -Attachment to rewind Igus cable carrier at the top (above the bearings).
- -Addition of a small cap to ensure contact with the limit of X axis (on the side, next to the linear bearing carriage below)
Original Modified X Axis carriage (PowerCode) X Axis carriage (Hephestos) File:Eje X carro A archcivos.zip
Left side motor mounting for Z-Axis
- -Incorporated coupling for cable carrier.
Original Modified Left side motor mounting for Z-Axis (PowerCode) Left side motor mounting for Z-Axis (Hephestos) File:I3-zbottom izq.stl File:Eje Z soporte inferior izquierda archivos.zip
End of the X Axis motor
- Added support material to the screw which adjusts the Z axis height.
- -The base has been elongated to reduced the clearance of the nut thereby preventing the screw from moving.
- -The screw hole has been shifted outwards to improve accuracy in the mechanical Endstop activation.
Original Modified X Axis left (PowerCode) X Axis left (Hephestos) File:EjeX izquierda.zip
RAMPS support
- Added three hooks. Each hook works by using cable ties to hold and collect all the cables connected to the RAMPS. By guiding the cables through the side and into the plate at the top left corner it facilitates cooling of drivers by not having cables directly above the heat sinks.
Original Modified RAMPS support (Witbox) RAMPS support (Hephestos) File:Suplemento RAMPS(original).stl File:Soporte RAMPS archivos.zip
Complete Kit
Complete Part Kit for Hephestos:
Bill of Materials
Tools
Electronics
Extruder
X Axis
Part Name Quantity
Chromed smooth rod 8mm x 370mm 2 M3x10 Screw - DIN-912 8.8 Class Black 4 M3x16 Screw - DIN-912 8.8 Class Black 2 M3x20 Screw - DIN-912 8.8 Class Black 2 M3x25 Screw - DIN-912 8.8 Class Black 1 M6x40 Screw - DIN-912 8.8 Class Black 1 M3 Nut - DIN 934 Class 8 Black 7 M5 Nut - DIN 934 Class 8 Black 2 M6 Nut - DIN 934 Class 8 Black 3 X Axis Carriage A PowerCode modified 1 X Axis Carriage B PowerCode 1 X Axis B623ZZ bearing Pulley PowerCode 2 X Axis Right PowerCode 1 X Axis tensioner B623ZZ bearingPowerCode 1 X Axis leftPowerCode Modified 1 X Axis left thread chain coupling PowerCode 1 X Axis Endstop (Hephestos) 1 B623ZZ axial bearing 1 GT2 pulley (20 theet) 1 LM8UU Linear bearing 1 Black cable tie 100x2.5mm 1
Y Axis
Part Name Quantity
Chromed smooth rod 8mm x 340mm 2 Black threaded rod M10x370mm 2 Black threaded rod M8 x 205mm 4 M3 x10 Screw - DIN-912 8.8 Class Black 7 M3 x16 Screw - DIN-912 8.8 Class Black 1 M3 x20 Screw - DIN-912 8.8 Class Black 1 M3 x25 Screw - DIN-912 8.8 Class Black 6 M3 Nut - DIN 934 Class 8 Black 7 M8 Nut - DIN 934 Class 8 Black 22 M10 Nut - DIN 934 Class 8 Black 8 M8 Washer - DIN-125 Class 6 Black 22 M10 Washer - DIN-125 Class 6 Black 8 M10 serrated Nut - DIN 6923 Class 8 Black 4 M10 Washer - DIN-125 Class 6 Black 4 Y Axis B623ZZ bearing Pulley 2 Y Axis belt holder. Prusa 1 Y Axis tensioner B623ZZ bearing http://www.thingiverse.com/thing:68185 1 Y Axis motor PowerCode 1 Y Axis Corner PowerCode 1 Y Axis base Endstop (Hephestos) 1 Y Axis frame Endstop (Hephestos) 1 GT2 pulley (20 teeth) 1 LM8UU Linear bearing 3 Black cable tie 100x2.5mm 11 GT2 belt 6mmx1m 1 Aluminium base 1 Acrylic base 220x220x8mm holes 3.5mm 1 B623ZZ axial bearing 1 Spring (long: 30,5mm ; Outside diameter: 4,5mm; Wire thickness: 0.45mm) 4 Glass Plate 220x220x3mm 1 Black Binder Clip (35x10mm) 4 Black cable tie 100x2.5mm 11
Z Axis
Part Name Quantity Chromed smooth rod 8mm x 320mm 2 Black threaded rod M5x300mm 2 M3x10 Screw - DIN-912 8.8 Class Black 16 M3 x18 Screw - DIN-912 8.8 Class Black 2 M3 Nut - DIN 934 Class 8 Black 2 Z Axis top support PowerCode 1 Z Axis bottom right support PowerCode 1 Z Axis Endstop (Hephestos) 1 Z Axis bottom left support PowerCode modified 1 Flexible coupling aluminium 5 to 5 mm 2 Black aluminium frame 1
Assembly Guide
Required tools not included in the BOM
Preparation before assembly
Prepare pulleys
- Materials Needed:
- Assembly:
Preparation of the motors
- Materials Needed:
- Assembly:
Embed nuts
- Materials Needed:
- Assembly:
- Parts to be embed with nut:
Preparation of motor cables
- Materials Needed:
- Cable length (from base of engine to end of connector)
Motor Total length (cm) Motor length (cm) Extesnion lenght(cm) X 85 30 55 Y 50 20 30 Z Right 45 15 30 Z Left 65 30 35
- Note: Cut four parts of the heat shrink tubing for the Motor wire to 2cm long.
- Note: Prepare motors of X and Y axis before mounting the engines, and the Prusa Z Axis, after mounting.
- Assembly:
- Note: Before soldering the cables of Z axis motors, pass the bare wire through the motor hole.
- Assembly:
Power supply cable preparation
- Materials Needed:
- Assembly:
Axis assembly
X Axis
Bearing Assembly
- Materials Needed:
- Assembly:
Prepare the X Axis tensioner
- Materials Needed:
- Assembly:
Enter the X Axis tensioner
- Materials Needed:
- The objective of the tensioner is to load or unload a belt easily once set.
- Note: It is necessary to sand/file the parts. The tensioner should slide perfectly into the part that holds it.
- Assembly:
- Note: The two nuts at the end are to be tightened together. Use a nut wrench on the adjacent nut to assist. This way you can ensure that the nuts are securely fitted to the screw. Now by using the wrench as shown in the picture, crank the tensioner to the side to achieve the required tension when fitting the belt.
- Note: Use the nut wrench when fitting and tightening the nuts on the screw.
Assembly smooth rod bearings
- Materials Needed:
- Assembly:
Prepare the X Axis Endstop sensor
- Materials Needed:
- Assembly:
Introduce the X Axis Endstop sensor in the smooth rod
- Materials Needed:
- Assembly:
Assemble the smooth rod into the side parts
- Materials Needed:
- Assembly:
- The length of the rod between the side parts (when assembled) should be approximately 31 cm.
Mount the X Axis motor
- Materials Needed:
- Assembly:
- Note: Orient the motor cable from the top.
Introduce the adjustment screw for the X Axis Endstop
- Materials Needed:
- Assembly:
Introduce the pulley on the X Axis motor
- Materials Needed:
- Assembly:
- Note: Use the 2mm Allen wrench to tighten the pulley to the motor axis by the chamfered area.
Z Axis
Couple the motor hold on the frame
- Materials Needed:
- Assembly:
Couple the Z motors
- Materials Needed:
- Assembly:
Note: Orient the motor cable to the frame
Attach the top tether of smooth rods
- Materials Needed:
- Assembly:
Note: It is necessary to sand the parts.
Prepare the Z Axis Endstop
- Materials Needed:
- Assembly:
Union X Axis with Z Axis: Insert threaded rods
- Materials Needed:
- Assembly:
Union X Axis with Z Axis: Introduce smooth rod
- Materials Needed:
- Assembly:
Union X Axis with Z Axis: Union with X Axis:
- Materials Needed:
- Assembly:
Union X Axis with Z Axis: Flexible coupling
- Materials Needed:
- Assembly:
Union X Axis with Z Axis: Z Axis Endstop
- Materials Needed:
- Assembly:
- Note: Paste with adhesive for plastics the step assembly 4 to the motor bracket.
Y Axis
Preparation of M10 threaded rod
- Materials Needed:
- Assembly:
Preparation of smooth rods
- Materials Needed:
- Assembly:
Union of smooth rods with threaded rods
- Materials Needed:
- Assembly:
Secure with nuts
- Materials Needed:
- Assembly:
Secure with cable ties
- Materials Needed:
- Assembly:
Preparation of Y Axis tensioner
- Materials Needed:
- Assembly:
Note: The 25 mm screw is used as shaft for the pulley and the 20mm screw for the tensioner.
Preparation of Y Axis motor
- Materials Needed:
- Assembly:
Preparation of the M8 threaded rods - Part 1
- Materials Needed:
- Assembly:
Preparation of the M8 threaded rods - Part 2
- Materials Needed:
- Assembly:
Union of the rods
- Materials Needed:
- Assembly:
Secure the structure with nuts
- Materials Needed:
- Assembly:
Preparation of the aluminum base
- Materials Needed:
- Assembly:
Secure the base aluminum with cable ties
- Materials Needed:
- Assembly:
Prepare the Endstop of the base
- Materials Needed:
- Assembly:
Secure the Endstop at the base
- Materials Needed:
- Assembly:
Place the belt of the Axis Y
- Materials Needed:
- Assembly:
- Note: Turn the set
- Note: Tighten pulley with 2mm Allen wrench
- Note: Screw out screw to slacken the tensioner
- Note: Align belt
- Note: Tighten the belt tensioner bolt tightening
Tighten all nuts
- Materials Needed:
- Assembly:
- Note: It is necessary to file the burrs.
Place the acrylic base
- Materials Needed:
- Assembly:
- Note: It is necessary to file the burrs.
Prepare the Y Axis Endstop on the frame
- Materials Needed:
- Assembly:
Secure the Y Axis Endstop on the frame
- Materials Needed:
- Assembly:
Union Y Axis with the X and Z axes: Snap axes
- Materials Needed:
- Assembly:
Union Y Axis with the X and Z axes: Fit and tighten nuts
- Materials Needed:
- Assembly:
Extruder
Prepare the carriage
- Materials Needed:
- Assembly:
Place the carriage in the X axis
- Materials Needed:
- Assembly:
Secure the carriage with a flange
- Materials Needed:
- Assembly:
Place the belt on the X Axis
- Materials Needed:
- Assembly:
Screw the Extruder support
- Materials Needed:
- Assembly:
Place the extruder
- Materials Needed:
- Assembly:
- Note: This step is necessary to remove the nozzle of the extruder.
- Nota: Secure with screws the Extruder.
Placing the blower nozzle and Hot end security
- Materials Needed:
- Assembly:
- Nota: The Hot end security is a opcional complement and no necessary for the correct printer working, but its use is highly recommended to avoid burns.
Place the glass on the base
- Materials Needed:
- Assembly:
Electronic
Place the RAMPS 1.4
- Materials Needed:
- Assembly:
Prepare the LCD control panel
- Materials Needed:
- Assembly:
Mount the LCD control panel on the frame
- Materials Needed:
- Assembly:
Tuck the wires in the X Axis chain stitch
- Materials Needed:
- Assembly:
- Note: Introduce the wires singly
Place the X Axis chain stitch
- Materials Needed:
- Assembly:
- Note: The 25 shackle chain stitch link the X Axis carriage with the X Axis left.
Introduce the Z Axis wires in to the Z Axis chain stitch.
- Materials Needed:
- Assembly:
- Note: Introduce in to the Z Axis chain stitch the X Axis motor and Endstop wires.
- Note: The 27 shackle chain stitch link the X Axis left with the Z Axis left bottom support.
Prepare the fan
- Materials Needed:
- Assembly:
Wiring and cable routing
Cable connection diagram
- Materials Needed:
Extruder wiring
- Note: Use a flange with the extruder wires.
Motors cable routing
- Note: Use a flange with the motors wires.
Endstop cable routing
RAMPS Wiring and cable routing
- Note: Use the flanges with the wires.
- Note: Guide the cables through the printed part that holds the RAMPS and secure them with the flanges.
- Note: Connect the clamp plate the fan cables and power supply.
Place the fan
- Materials Needed:
- Assembly:
- Note: Disconnect the LCD panel control Ramps before placing the fan and pass it through the hole in the workpiece.
Placement the filament holder
- Materials Needed:
- Assembly:
- Note: Disconnect the LCD control panel of Ramps before placing the fan and pass it through the hole in the workpiece.
Printer settings
Z Axis adjustment
- Before printing with your printer you must calibrate the screw that adjusts the height of the Z axis so that the extruder is to the correct height of the base. To do this, follow these steps:
- -Put the same height ends of the X Axis. Thread each axis manually until both are at the same height.
- -Tighten the set screw everything without possible forcing the printer part.
- -Use the LCD control panel to bring the extruder to home.
- Control > Move Axis > Auto home
- Note: Make sure that the Endstops are being touching correctly by their respective axes.
- -Adjusts the position of the endstop sensor adjustment screw and repeat the previous step (bringing the Z axis to home).
- -If the adjustment isn't correct, repeat the previous step.
Level plate
- Once Z Axis is adjusted, is necessary level the plate.
- Using the LCD control panel, start the leveling program.
- Control > Level plate
- The program moves the extruder at four points of the base, where you must adjust the screws on each corner, so that you can pass a sheet between the extruder nozzle and glass. Must feel the friction produced by the extruder in the paper passing therebetween.
Extruder obstruction
- If a blockage occurs in the extruder, follow the next step:
- You must hate the extruder at 220 ° C and insert the 0.4mm needle into the nozzle until you see it come out the other end. After you must clean the needle of adhered plastic.
- If a blockage occurs in the extruder, follow the next step:
Hello world: Your first print
- If you followed all steps of this manual, you should have your Prusa i3 Hephestos ready to do his first print!
- First you must laminate the 3D design. The 3D designs must be in .stl. For this, you can follow our guides for some used programs.
- Slic3r guide: https://www-cdn.bq.com/file/Witbox/Manual_Slic3r_ES.pdf
- Repetier-Host guide: https://www-cdn.bq.com/file/Witbox/Manual_Repetier_ES.pdf
- Cura 3D guide: https://www-cdn.bq.com/file/Witbox/Manual_Cura_ESP.pdf
- Note: Remember that Prusa i3 Hephestos area is 215x210x180 mm.
- Once you have the g-code file, save the file in a SD card. Insert the SD card in the LCD control panel slot. In main menu select "Print from SD". Now select your g-code file. The printer will start automatically. You can view the progress of the part and the extrusion temperature from the LCD panel of the printer. When printing is completed remove the glass base by removing the clamps. With the base resting on a glass table parts removed by pulling them tight.
- You need apply lac on the glass for the correct adhesion of parts!
Annex
Firmware load
For load a new firmware follow the next steps:
1. Donwload the firmware. In RepRap wiki you can find a entire list of available firmwares:
Link: http://reprap.org/wiki/List_of_Firmware
2. Here are some of the most popular firmwares and our modification of Marlin:
Marlin: http://reprap.org/wiki/Marlin Sprinter: http://reprap.org/wiki/Sprinter Marlin Hephestos: File:Marlin Hephestos.zip
3. Download and install Arduino software from main site:
Link: http://www.arduino.cc/en/Main/Software
4. Inside of firmware folder, you must open .ino file with the Arduini IDE.
5. Once open, will appear one tab called "configuration.h". In this file you can configurate the params of your printer.
6. When you complete configuration, load program into Arduino Mega.
Drivers calibration
Materials Needed
This step must be repeat with all drivers, you will need two motors for Z Axis driver calibration.
Intensity for each Driver
Driver | Intensity (mA) |
---|---|
X Axis | 250 |
Y Axis | 250 |
Z Axis | 450 |
Extruder | 680 |
Arduino with RAMPS | aprox. 74 (no regulable) |
Wiring
Is necessary connect one endstop sensor and thermistor, because of firmware firewalls.
Multimeter preparation
Connect the multimeter in serial connection between Arduino and power supply. Put multimeter in intensity measurement mode.
Multimeter adjustment
Connect Arduino Mega to computer. The flowing current is 74 mA aprox. (this may differ between plates). Open Pronterface, select the correct port and connect to Arduino.
You must move the motor using Pronterface interface. Measure the current and regulate this using the Ceramic screw trimmer together with the mulitmeter. The current should be set to the sum of the current circulating in the PCBA and the current in the motor. For example, in X Axis current must be 74 mA + 250 mA = 324 mA.
Pre-heat or send the M302 command for completing the extruder calibration.
Arduino needs to be reset before calibrating the next driver.
Pronterface donwload link: http://reprap.org/wiki/Printrun