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Extruder motor running at the wrong speed

Posted by natan 
Extruder motor running at the wrong speed
January 18, 2019 04:53PM
Hello. I have a Prusa i3 pro W. The extruder motor on my 3D printer seems to be working at the wrong speed. When I command to extrude 100 millimeters of filament at the speed of 1 millimeter/second, the extrusion lasts for much less than 100 seconds, which is what it should be. It looks like the motor speed is much faster than 1 millimeter/second. It does not properly obey the software speed command. I've already calibrated the extruder. When I command to extrude 100 millimeters, 100 millimeters is extruded. So the problem should only be at speed. The other motors are working properly. I used a timer to measure how long the extruder motor is working. I use the Repetier Host, already tried with other software, but it did nothing. Any help will be welcome.
Re: Extruder motor running at the wrong speed
February 04, 2019 08:25PM
Hello, Natan.

It is important to know that stepper motors operate on a rotational angle, and have a number of steps per rotation. The distance that the filament advances depends on several factors, including the diameter (actually the circumference) of the feed gear and the steps per rotation. This is the same with the motion (axis) steppers, but depends on belt pitch, number of teeth on the gear and steps per rotation.

The control board you are using probably has (should have) jumpers that allow you to set microstepping, and your firmware has a setting for steps/mm and feed rate, which are functions that affect mm/sec.

Sorry if it sounds confusing, just trying to explain that mm/sec is not directly related to the stepper, but a combination of other factors.

If you are getting the correct length, but are not satisfied with the time it takes, you should adjust the feed rate of your E stepper in firmware.

Hope this helps...


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Re: Extruder motor running at the wrong speed
February 05, 2019 12:56PM
What firmware are you using? how did you adjust the extrusion rate?

If you used an extrusion multiplier to adjust the extrusion amount, the amount that the firmware thinks that it's extruding might not be 100mm, There can also be some pretty funky things with volumetric extrusion.

It might also be worth seeing if your X and Y axes also move at a different speed. See if commanding those axes to move 100mm at 1mm/s results in a move for the same amount of time, assuming that they are also calibrated to move the correct distance.

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