Cube 20 x 20 mm comes out printed 20 x 21 (Y) mm. How to fix this.
I saw some problems that printed objects were not close enough to the expected measurements. (circle looks a bit like an ellips etcetera. A PCB mount with holes on 49 x 58 mm came out 49 x 56 (so it bit too short)
No shifting of layers to be seen. Prints looks fine. So what could be wrong?
I did a calibration cube 20 x 20 mm. And it came out 21 mm in Y-direction.
- So not sure if it is always too long or too short.
Wondering what is causing this. Things changes last weeks: PS 2.8.4. (set G2G3 -> on) nozzle from 0.4 to 0.6
There was a thread a couple of weeks here (I cannot find it back, I remember I commented in the thread myself 🙁 )
Maybe you have an idea?
Next is, that I am going a to print a gcode cube (to eliminate the slicer as a cause)
We will do what we have always done. We will find hope in the impossible.
With a 0.6mm nozzle your default extrusion with is either 0.65mm or 0.69mm depending on how you are set up.
If you are measuring external dimensions and you do not have 'External perimeters first' set then your error is under 70% of an external perimeter width (doubled for two exteriors).
So: repeat the exercise for about 100mm and then a near full bed, determine whether it is a fixed or proportional error; and calibrate.
Cheerio,
RE: Cube 20 x 20 mm comes out printed 20 x 21 (Y) mm. How to fix this.
OK. I will do some tests. And come back on it.
We will do what we have always done. We will find hope in the impossible.
RE:
results of test: Two long strokes 150 mm long. One in X direction and one in Y-direction. (checked in preview: outside perimeters printed first. )
The X-version = exactly 150 mm
The Y-version = 152 mm , that is 1.3 % off
I also measured the short sides
The X-direction = 10 mm
The Y-direction = 10.25 mm, is around 2,5 % off.
NB: The object I printed this morning should have been:
In X-direction 58 mm.
Measured after printing 60.1 mm = about 3% off
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There is no big difference . So maybe a small correction of the Y-calibration? But not completely proportional. So maybe a part is proportional (1.3%)
and there is something else too?
Then there is the difference in X and Y direction.
1. If this was caused by extrusion_width only, would not we see the same difference in X and Y direction?
2. If there is some other cause, why are all three measurements in X-direction correct? That suggest there is another cause in Y-direction.
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Looking forward to your reactions. I can test suggestions in 2-3 days.
We will do what we have always done. We will find hope in the impossible.
Look at it this way - your uncorrected parts are more accurate than most hand woodworkers or blacksmiths could manage. Regard them as blanks ready for finishing.
But:
Yes, the X values are a bit worrying. You would expect them to be about an extrusion width wider - the gcode generally defaults to the midline of the extrusion track...
In the ancient days of 3D printing (and CNC machining) the calibration calculation would be something like:
Calibrated_X=Desired_X+Fixed_X_correction+(Desired_X*proportional_X_correction)
With similar calculations in Y and Z.
Either use this as a factor in your CAD or use it for scaling your parts in slicer. This is why you have Scale factors in the Object manipulation pane of PrusaSlicer.
For maximum accuracy you will now want to factor in the thermal contraction of your filament as it cools from printing to ambient temperatures.
Cheerio,
RE: Cube 20 x 20 mm comes out printed 20 x 21 (Y) mm. How to fix this.
temporary solution: Y = 0,9633 * Y
No idea what happened to the machine (it did not fall on the floor or whatever 😉 ) but XYZ-calibration will not work. (skew is 2.5+).
Now working on another printer (voron 0.1). As soon it works, I will take the MK 2.5 apart en rebuild the structure.
We will do what we have always done. We will find hope in the impossible.
RE: Cube 20 x 20 mm comes out printed 20 x 21 (Y) mm. How to fix this.
After reading a lot, the only cause for the wrong dimension is probably that the belt has stretched of time. (so will have to replace the belt sooner/later).
The semi-temporary solution for this is to set Ysteps in the printer. Have done this by:
M503 ; retrieve values from memory
M92 Y 96.33 ; set new value
M500; save to memory
We will do what we have always done. We will find hope in the impossible.