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funBart

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Dec 18, 2013, 4:58:49 PM12/18/13
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Re: hole diameter not matching the .stl file
« Reply #7 on: December 05, 2013, 03:07:59 PM »
PenskeGuy, I didn't know that! What I don't understand: is that inset always wrong with internal holes, so one extrusion width to much to the center of the hole (as I understand not a half extrusion to the model, but a half extrusion to the hole?)

One person figured that the tool path is on the "wrong" side of the internal boundary of the hole. Going across the hole, with this being the case, two times the error is created; resulting in a 1mm undersize for a .5mm nozzle. Another person speculated that it was due to Arc Compensation, where slicer paths are short straight segments that effectively encroach on the hole as they cut across the flats. This was later proven to not be the case. When Oversample resolution was made finer, to make the path segments far shorter and, thus, less encroaching upon the inner circle, the printed hole diameter did not change.

Or is it only when using 'inset' on the Style tab resulting in this error?

Inset doesn't have anything to do with it. Happens all the time.
« Last Edit: December 05, 2013, 03:12:55 PM by PenskeGuy »
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dannydefe

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Re: hole diameter not matching the .stl file
« Reply #6 on: December 05, 2013, 02:58:39 PM »

thanks for the input guys, before I printed  this part I printed out a 100 millimeter Square pattern , the dimensions were dead on. I do have the flow tweak turned up hi, I will experiment with this. As you can see from the photos the Dia is quite large so speed is not a problem . And the file was modified in solidworks and netfabb for proper dimensions prior to printing. the Dia is supposed to be just under 22 mm, but it is printing at 20.32 mm.






funbart

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Re: hole diameter not matching the .stl file
« Reply #5 on: December 05, 2013, 02:06:21 PM »
PenskeGuy, I didn't know that! What I don't understand: is that inset always wrong with internal holes, so one extrusion width to much to the center of the hole (as I understand not a half extrusion to the model, but a half extrusion to the hole?)
Or is it only when using 'inset' on the Style tab resulting in this error?
Bart
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PenskeGuy

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Re: hole diameter not matching the .stl file
« Reply #4 on: December 05, 2013, 01:38:38 PM »
We nailed it down to the way that the Perimeter is currently calculated. The external path is properly inset from the surface but the interior surface apparently does the same; not toward the internal volume but just "in", in a manner of speaking. IOW, the inset is on the wrong side of the path on internal holes. It is most prevalent on small holes, where the path is short and completes really quickly; thus having a greater effective temperature for that section of the path. In these cases, with Loops set to go from Outside > In, the Perimeter completes quickly then the Loop that is laid down right next to it is extruded and the heat buildup deforms the hole. Only way currently to address it, until a new build is released is to compensate with the model itself.
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funbart

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Re: hole diameter not matching the .stl file
« Reply #3 on: December 05, 2013, 12:47:27 PM »
From what I understood from Jonathan is that Kisslicer is pretty dialed in regarding the translation of the stl to the resulting dimensions represented in the Gcode. For example: it calculates that the center of the extrusion of the perimeter has an offset of the half of the extrusion width as described on the 'style' tab.


But -of course- that all can be correct but not giving the right results. Things I can think off:
  • is your Diameter under the Material settings good dialed in? First by measuring it with a calliper in various directions. I do this as well with printing a complete filled 20x20x10mm cube. Because when you have set a too small number in the diameter setting it results in overextrusion, pressing the extrusion 'outside' the model.
  • Did you have the flow tweak on the Material settings at '1' ? Because when having set a setting like 0.5 or 1.5, KS isn't compensating to my knowledge.
  • Under Printer //Hardware I have experienced problems with a to high number under "loop/solid infill overlap" as well by to much material extruded at that overlap and pressing the extrusion a little outwards.
  • Maybe you speed is a little to high, resulting in 'overshooting"?
  • Under the tab "Misc // Oversample resolution" : a to high number can result in a less precise translation to the Gcode and maybe result in numbers giving a to low 'resolution' and unwanted output.
  • Are you sure the stl is really good, so actually describing the holes as you wanted? When exporting from a modeler with for example 'perfect circles' as a hole, the stl output is still an interpretation of it with a bunch of triangles, so as well a 'lower resolution' then described in the modeler.
Finally: you can compensate a little with the setting "inset surface"  on the style tab. By this the complete model (including the holes) will shrink or expand a little in the XY plane (Not the Z). So you can dial it in that the holes got the right diameter, but it affects the perimeter of the complete model as well.


Maybe others have more ideas.


Hope it helps,
Bart
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Dirty Steve

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Re: hole diameter not matching the .stl file
« Reply #2 on: December 05, 2013, 12:40:12 PM »
Interior holes and especially small holes will turn out smaller than the model file due to the ABS/PLA shrinking inward as the print cools.

I usually correct for the shrinkage by making the holes a little larger in the model to get the correct printed size.
« Last Edit: December 05, 2013, 12:41:46 PM by Dirty Steve »

dannydefe

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hole diameter not matching the .stl file
« Reply #1 on: December 05, 2013, 11:31:26 AM »
I'm having a little trouble with hole diameter not matching the .stl file info.  Could I be missing a setting someplace?
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