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walls too thick

Posted by mrkaras 
walls too thick
August 02, 2016 08:16AM
no doubt this has been answered before but my walls are too thick, when I print a single wall test object using slic3r the wall is thicker than the number at the top of the gcode says. I tried recalibration the extruder steps to make the wall the right thickness but by the time I got that right it was quite a bit low (probably 10%) and under extruded everything else
Re: walls too thick
August 02, 2016 08:57AM
The extruder works with the slicer to extrude filament by volume of plastic. Volume calculations involve length (which is probably what you calibrated) and filament diameter (which you probably didn't calibrate). When you slice you must either tell the slicer the real diameter of the filament or use the extrusion multiplier (or flow, depending on the slicer). The problem is that filament is almost never the nominal diameter of 1.75 mm. A little over and you'll get over extrusion, a little under and you get under extrusion.

Using flow/extrusion multiplier: slice a single or double walled object, print it, and measure the wall thickness. Adjust the extrusion multipler/flow value in the slicer to get the measured wall thickness to match the slicer wall thickness. Write the extrusion multiplier value on the filament spool and use it whenever you slice objects that you will print with that spool of filament. Use the ratio of target wall thickness / measured wall thickness for the flow/extrusion multiplier.

Use filament diameter: pull a few meters of filament off the spool and measure the diameter with a caliper down to 0.01 mm, changing the caliper's orientation, at 20-30 points and calculate the average diameter. Mark that diameter on the spool. Use that diameter whenever you slice an object to be printed with that spool.

Advanced option: use volumetric extrusion. Tell the slicer that the filament diameter is 1.128379 mm when you slice. That makes your gcode file independent of filament diameter. You can use the same gcode for any diameter of filament (and so any color) without reslicing. Enter the measured average filament diameter when you print by using the M200 command (if you're still using host software) or via the LCD panel, depending on the controller board in your printer. You can go a step further by setting extruder and bed temperatures to zero when you slice. That will make the gcode independent of both filament material and diameter (assuming other settings such as retraction, speed, etc., are the same for different materials).

See [reprap.org] and pay attention to the e steps fine tuning.

Edited 1 time(s). Last edit at 08/02/2016 08:57AM by the_digital_dentist.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: walls too thick
August 02, 2016 06:13PM
I have measured the filament diameter (set as 2.8mm), I tried using the flow/extrusion multiplier but it says you shouldn't need to go below 0.9, I needs something like 0.75 from memory.

I'm using repeater-host with slic3r, marlin firmware and I do have an LCD, perhaps I need to try the volumetric extrusion
Re: walls too thick
August 07, 2016 09:08AM
testing tonight, the "external perimeters extrusion width = 0.40mm" but my single wall cube is over 0.8mm
Re: walls too thick
August 07, 2016 09:55AM
What slicer are you using? Is the nozzle diameter set correctly in the slicer? When you print the single walled cube, how tall is it and how are you measuring it? How are you setting the wall thickness in the slicer?


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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