Bondtech LGX Large Gears eXtruder is smarter, smaller, lighter

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, ...