Pressure Advance killing extruder motor

[dc42]

With such a high gearing ratio, you don't need much torque but you do need low inertia and high speed. So I suggest choosing a motor with low inductance, modest torque, and a high ratio of holding torque to rotor inertia. Run it close to its rated current (e.g. 85%).

[Edgars Batna]

@garis said in Pressure Advance killing extruder motor:

Perhaps I haven't used a sufficiently high magnifying glass to understand what defects I should be observing or tolerating. My printing experience is limited and just now I am reprinting a few parts to upgrade the originals I printed for my Hypercube now that it is working.

You need to use a magnifying crystal ball, preferably with Christmas decorations within the ball.

For the XY motors this is of concern but for the extruder I could imagine some/much of this resonance would be absorbed by the plastic, and perhaps some under extrusion if steps were missed. For a stepper with 2,600 steps that is likely to be of minor concern???

At 40:1 there's basically no resistance whatsoever on the motor end to absorb anything, so there is just the rotor.

[gnydick]

@dc42 thanks. Can you give an example of what qualifies as those suggestions? low inductance, modest, torque, high ratio of holding torque to rotor inertia?

[garis]

@dc42 My pancake has more than enough torque @ 30:1. What is the reason to use high current?

[dc42]

@garis said in Pressure Advance killing extruder motor:

@dc42 My pancake has more than enough torque @ 30:1. What is the reason to use high current?

The reason to use a motor current close to the rated maximum is to provide enough torque to overcome the inertia of the rotor, because high gearing means you need high acceleration.