3D Printing (Part 12)

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3D printing can be tiring for the nerves… For a week or so, I was enable to print full size parts without enduring severe problems such as splitting layers, irregular faces and even gaps. Here is an illustration of the prints before the fix (on top) and after the fix.

The first layers where almost alright and the print was going worst and worst: awful ! I carefully and visually checked the printer and found nothing. It was obvious from the beginning that I faced a feeding problem. Usually, these problems come from clogged nozzle, clogged insulator, etc. So I checked and cleaned the whole filament path: no way. I ran a temperature measurement on the heater block: it was just fine. So what ?

I made the decision to install the printer on my desk and watch it working: “Watch out printer, big brother is watching you”. After few minutes, I heard little “klunks” next to the extrude stepper motor, once in a while. I squeezed the filament and felt that the filament was getting one step backward at each “klunk”. As the wheel was perfectly clean (I never had the least problem on this side) and the pressure mechanism free to move, my thoughts were that I was facing a torque problem. Firmly pressing the filament toward the feeder was helping quite a lot and resulted in a significant improvement of the printing quality. So that I decided to increase the current limit for the extruder driver (Check the procedure here) to 2.5 A which is the maximum rating for the stepper motor (Specifications here). In this way, the stepper motor can cope with the back-pressure from the filament being pushed toward the nozzle. Then I made sure that this increase had no dramatic effect on the motor and I checked it operating temperature using a PIR thermometer has shown here.

The stepper motor temperature stays below 60°C which is just fine. And… tadaaa, the problem has gone away !


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