XY SIZE COMPENSATION - UNITS  

RE: XY SIZE COMPENSATION - UNITS

XY  size compensation value, IS a crude tool which enlarges or reduces the XY Dimensions of an artifact by the given amount. this is not a ratio based tool. and it is not selective ie, you cannot choose to increase only the X dimensions or only the Y dimensions. the tool works on any 2 dimensional artefacts in the XY Plane, the artefacts do not have to be symmetrical

If you would like a thermal expansion tool you would need to communicate your idea to the developers via the Prusa Slicer GITHUB Page, proposing how the tool would integrate with Prusa slicer. 

RE: XY SIZE COMPENSATION - UNITS

It would be nice to have it a % scaling factor that can be stored as part of the filament profile.  You really need to scale the part because shrinkage causes everything to move.

By doing this you can compensate for different shrinkage amounts for different materials. 

I'll add though that the physical size you print something is only a small part of compensating for shrinkage.  There are so many variables involved like warping, extrusion multiplier, number of perimeters, infill, #of top and bottom layers etc., and if you print large parts like on the XL you open a whole new can of Worms because large parts magnify all of these affects. 

If your printing figurines it probably is not critical, but for functional parts these things become important.

RE: XY SIZE COMPENSATION - UNITS

1) XY size compensation

I tought that XY compensation in "printing setting/slicing" could scale printed X and Y. But the unit at right of the box, millimeter, is'nt coherent with this hypothesis (should be % or no dimension).

After a long chat with Prusa support, it appears that XY compensation does'nt scale printed X and Y.

Here is what I understood :

XY compensation only change the gaps between close (how much ?) parts, e.g. :

    0 -> printed gaps are the same as on model

-0.1 -> printed gaps are reduced by 0.1 mm

+0.1 -> printed gaps are increased by 0.1 mm

This can be usefull to print articulated or sliding parts.

Am I right ?

2) Thermal shrinking compensation

With Prusaslicer, the only way for scale the printed model is to use the "object manager" panel on the right of the screen to specify the X, Y and Z ratio, or the graphic tool on the left of the screen.

I think that the "good" scaling value to adopt for compensate thermal shrinking depends not only on the filament material, but also on the printing history :

During printing, the filament cools from injection temperature down to the model temperature. Model temperature varies from bed temperature to a some celsius above ambiant temperature. At the end of printing, the material cools down to ambien temperature. So the temperature history of a small filament chuck is complex and variable. First layer remain at bed temperature, next layers cool down at decreasing (then increasing?) temperature, following delayed evolutions (uppers layers cools last). Furthermore, the thermal shrinking of a layer can be braked by the layer below, wich is already cooled and don't want to schrink. So the material can creep and residual thermal stress will be present in the finished printed model.

=> Has any body heard of a theoric work to modelise this complex cooling down and predict the thermal shrinking map ?

I believe that associating a filament and scalling XY (and Z?) coefficients is possible, but inefficient, except for a almost fixed configuration (model geometry+slicing + 3D) printer.

For now, my point of view is that accurate printed geometry can be obtained, but only by empirical scaling deduced from the discrepancies between model geometry and printed geometry.

=> Any other idea ?

RE:

Hi

XY  size compensation value.

In the description of the function it is described that it can help with tuning hole dimensions.
I understand that this parameter is a combination of XY size compensation and hole compensation known from superslicer?

If I set the parameter to +0.1mm the dimensions will increase by 0.1 in each direction i.e. the circular holes will decrease by 2x0.1mm?

Did I understand that correctly?

RE: XY SIZE COMPENSATION - UNITS

Yes, mostly.  XY is just a layer adjustment tool, its is not a combination of super slicers XY and hole compensation.  PS does not have any specific hole compensation like SuSi does.  SuSi is a fork of PS and so added many new and different parameters.  Also be careful of 'gotchas' when using both.  Some settings work differently even though they have the same name when it comes to values.  This can catch you out.

Its quite easy to see if you add a few sample objects and slice with different exaggerated XY settings.   If you add a 20mm cube and slice with a +1 setting your cube will be 22mm across both X and Y.  That's because all the perimeters are 'grown' out by 1mm.  A -1 setting will result in an 18mm cube.  Ok that's for a basic solid.

Now take your 20mm cube and add a 10mm hole in the z axis that goes top to bottom.  With a +1 setting you will end up with a 22mm cube with a 8mm hole running through it.  ALL perimeters are grown outwards, so they grow into the hole as that is outwards from the interior of the solid shape.
A -1mm setting will give you an 18mm cube with a 12mm hole.  

As Joan says, its a blunt tool.  

RE: XY SIZE COMPENSATION - UNITS

Thank you for your thorough and comprehensive response.

Best regards.