Bondtech LGX Large Gears eXtruder is smarter, smaller, lighter

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Do not connect a LGX® stepper motor to a printer's cable without checking the wires and pins of the connection cable.

Not all printers are ready for a direct connection with the LGX®. Some use stepper drivers with no protection and this may damage them.

Before connecting a LGX® to any 3D printer check if the connector pins are wired as shown below:

After start of service, if the LGX® is turning in the wrong direction, swap the top (or bottom) pair of wires to make a correction:

You may be interested to know

How to identify the coils on a Creality stepper motor

How to identify the coils on a Bondtech stepper motor

Reversing feeding direction by swapping the coils' wires

Extruder and Stepper Motor go together

Preferably, you should always use the extruder attached to the stepper motor when you mount it on a printer.

If you need to put a plate in between the stepper motor and the extruder please notice that you need longer screws, and the max supported thickness is 2.6mm.

This image below shows what screws are used on the LGX®, and the red ones are used to attach the stepper motor and extruder:

To use a plate in between the stepper motor and the extruder, you need to replace the stock M3x27 low head screws with the 3 M3x30 low head screws we send in the accessories bag, which are compatible with printer plates of thicknesses between 0.3 and 2.6mm.
Don’t use a plate in between without using the longer screws.

Technical Specification

LGX extruder

• e-steps value : 400 using 16 microsteps; 800 using 32 microsteps.
• Drive wheels : hardened steel;
• Materials compatibility : abrasive; rigid; semi-flexible; flexible; and soft.
• Mounting holes : M3
• Mounting patterns : bottom anterior (2 points); left (2 points), right (2 points), front (4 points), back (4 points)
• Holes on the sides of the LGX™ : 5 mm depth
• Holes on the bottom of the LGX™ : 12 mm depth
• Max tightening torque on the extruder screws is 0.3 Nm

Using a plate between the extruder and the stepper motor

• Max thickness : 2.6 mm
• Optimal Thickness : between 0.3 and 2.3 mm;

Optimal Thickness allows full teeth engagement between the motor gear and the main double gear.

For Klipper users

rotation_distance = full_steps_per_rotation * microsteps / steps_per_mm

rotation_distance = 200 * 16 / 400
rotation_distance = 8

The above calculation assumes the following parameters:

• stepper motor is a 1.8 degrees motor hence 200 as full steps per rotation;
• microsteps are set to 16;
• e-steps value recommended for the LGX is 400.

 

Although we recommend to use the rotation_distance instead of the gear_ratio, we inform the LGX gearing ratio is 44:14, 37:17.

• To use the LGX directly attached to the hotends listed below,
  PTFE tube lengths should be:
  • Old Mosquito/Mosquito Magnum : 10 mm
  • New Mosquito/Mosquito Magnum : 11 mm
  • Copperhead screw mount : 30 mm
  • PTFE tube should be cut straight on both ends.
  • Slight chamfer inside is recommended, but not mandatory.

• retraction speed : 35 mm/s
• retraction distance (bowden) : ~5 mm (0.4 + tube length[mm] x 0.015)
• retraction distance (direct drive) for rigid materials : 0.4 mm
• retraction distance (direct drive) for soft materials : 3 mm

• Max Environment operating temperature : 70°C
• Max stepper motor running temperature (using LGX) : 80℃
• Recommended stepper motor Current (using LGX) : 0.45 to 0.60 A

• LGX™ DD net weight : 218.6 g
• LGX™ B net weight : 224 g
• Package measurements : 80x103x73 mm
• Package weight : 269 g
• Download the LGX Technical Drawings here.

Custom Stepper Motor for Bondtech LGX™

• Requires cable with PHR-6 connector
• 2 phases
• DC 3.1 V
• Max 0.7A / phase

  To use the LGX®, run the stepper motor with currents between ~0.45 and ~0.65A:

  Be vigilant regarding the stepper motor surface temperature.
  Keep it cool enough to touch. Lower Vref otherwise.

• Class H motor, rated up to 180°C
  • Max recommended environment : 70°C
  • Max temperature at this environment temperature can go up to 130°C on account of the self heating.
• Download the stepper motor Technical Data Sheet here.

How to change the Current using Vref

It is very hard to read the current being fed to stepper motors. To determine that current we rely on the Vref value. The Vref value is a voltage reference measured in VDC that can be read using a multimeter. It helps us setting the current output of the stepper motor driver.

Different 3D printer mainboards use different stepper motor drivers. Each type of stepper motor drivers has its own formula to calculate the required Vref to get a specific current. Here are some examples:

• TMC stepper drivers.
  The formula for these drivers is Vref = ( I * 2.5 ) / Imax
  Where I is the target current value measured in A; and Imax is 1.77 on regular mode and 1.2 on SilentStepSticks mode.

• Pololu A4998.
  The formula for these drivers is Vref = I * 8 * R
  Where I is the target current value measured in A; and R is the Sense Resistor value, that depends on what board are you using. Melzis use 0.1. The Creality Silent boards use 0.15, ...
  
  

Pre-tension Lever Positions

Position 0

When facing the LGX eXtruder push the lever all the way to the left.

Use it to load or unload filament without pressure from the drive gears.

Position 1

When facing the LGX eXtruder push the lever all to the left and then 1 position to the right.

Use it to work with rigid materials.

Position 2

When facing the LGX eXtruder push the lever all to the left and then 2 positions to the right.

Use it to work with semi-flexible materials
Shore hardness of ~95A

Position 3

When facing the LGX eXtruder push the lever all to the left and then 3 positions to the right.

Use it to work with flexible materials
Shore hardness between 85 and 95A.

Position 4

When facing the LGX eXtruder push the lever all to the left and then 4 positions to the right.

Use it to work with soft materials
Shore hardness between 75 and 85A.

Position 5

When facing the LGX eXtruder push the lever all to the left and then 5 positions to the right.

Use it to work with very soft materials
Shore hardness between 60 and 75A.

Hot Stepper Motor?

To adjust the LGX's stepper motor current use one of the following methods:

Change the current using Vref on a multimeter

It is very hard to read the current being fed to stepper motors. To determine that current we rely on the Vref value. The Vref value is a voltage reference measured in VDC that can be read using a multimeter. It helps us setting the current output of the stepper motor driver.

Different 3D printer mainboards use different stepper motor drivers. Each type of stepper motor drivers has its own formula to calculate the required Vref to get a specific current.

You can learn how to adjust the Vref by watching the video or by following this guide as example:

• Current adjustment on Creality units

Lowering current on Ender-6

Change the current without a multimeter

If your printer doesn't have DigiPOTs, and in case you don't have a multimeter to visualize the Vref you may still adjust the current fed to the LGX stepper motor by trial and error.

Use the analog potentiometer (inside yellow ring)next to the extruder's stepper motor driver (below the heatsink inside the red ring), and turn the potentiometer a few degrees at a time.

Rotate it counter clockwise to lower the current, or clockwise to increase it.

Between each iteration, use the printer and check if the stepper motor is not getting hot neither it is loosing steps.

Lower current if stepper motor is too hot to touch.

Increase current if stepper motor is loosing steps.

Change the current using DigiPOTs

DigiPOTs are digital potentiometers which resistance can be varied by digital communication instead of turning a knob, like seen above.

On a 3D printer with a mainboard carrying DigiPOTs, you may use the user interface of the unit (if that feature is available) or even Gcode commands to set the current of the different stepper motors.

On RepRap units with DigiPOTs, the M906 command may be used to change the Extruder stepper motor current M906 Ennn, where nnn is the amount of milliamps desired.

Marlin also uses a similar command. M906 Ennn sets the current on TMC drivers. On stepper motors with other drivers and DigiPOTs, you may also set the current in milliamps using the command M907 Ennn

Product Videos

The LGX extruder – How It’s Made

LGX Webinar

STEP Files To Download

Click the links below to download STEP files with simplified geometries of each available setup.

• LGX™ Bowden;
• LGX Direct Drive with Copperhead screw mount hotend;
• LGX Shortcut Copperhead with Right-hand side heatsink and fan;
• LGX Shortcut Copperhead with Left Hand side heatsink and fan;

LGX™ Interface Plug geometry.