Issue: Stalling Extruder Stepper Motor

A user have reported a stalling Extruder stepper motor.

Stalling is when the motor attempts to turn but is unable to due to an incorrect setting.

While I determine how great the affected user base is, there is a workaround:

• Find the setting: #define EXT0_MAX_ACCELERATION 5000
• Reduce the value (currently 5000). The user reported great results at 2000

While higher acceleration is nice, it is not a requirement.

Acceleration is just the how fast it reaches the target speed, and then how fast it needs to loose the speed to stop in time.

An acceleration of 4000 will take 1/2 the time an acceleration of 2000 will take (and also half the distance).

Think of it as a racing car vs your standard car. The target speed is the local speed limit for the road you are traveling on (for example 120mm/s is a 120km/h in scale). This limit is an absolute and cannot be exceeded. The 2 cars are next to each other at a robot/traffic light (whatever you call it in your country), when the light turns green. Both cars accelerate to reach the target speed, then remains at the target speed until it is time for them to brake for the next traffic light.

If the distance between the 2 traffic lights are very great, like 5km, both cars will reach the target speed, but the racing car (due to the higher acceleration) will reach the end a while before the standard car will. If the distance between the 2 traffic lights are very short, neither car will reach the target speed, but the racing car will reach a higher speed and again arrive before the other car.

Being able to accelerate faster speeds up the print, however:

• For the Extruder:
  • t he distances is usually very small, so the acceleration is higher than for other axis (my max for X and Y is 1000 while printing and 2000 for a simple movement), to still be able to reach a reasonable speed.
  • the difference between 5000 and 2000 is very little (might add only a few minutes to prints over 5 hours long).
• For X, Y and Z:
  • Here it is important to know the weight each axis needs to move. On a D4 with dual extruders, that carriage weighs about 1kg (from what I have read) - moving a lot of mass, requires slower accelerations (since the motors also need to be able to stop it again) and slower speeds.
  • The D5 have a Bowden setup with 1 main advantage: the head is extremely light - easier to move and stop, thus it can move at faster speeds (although the printing while moving have limits).