Dash-dot line appear continuous

Good morning.
I set up a layer for the axis line, with linewidth 0.18 and linetype dash-dot.
When I print a pdf, the dash dot line appear as continuous line.
With the smaller dash dot line, I can see one line and one dot, so I suppose that I see it as continuous line because the length of the dash part is too much.
How can I set up?

Thanks

You can not  change the appearance of linetype. It's printout is fixed same way as linewidth, regardless how it looks on screen and of scale.
linetypes.pdf
Could it be you accidentally have set a very small sheet size combined with fit to page?
 

I have set an A4 papersize, with scale 1:1, and the drawed part has a width of 80 mm.

This is how it appear on librecad



this is the print preview on librecad, it's correct



And this is the exported pdf





As you can see, the line is different.
Moreover the image is not in the same position as in the print preview.

As I said, the size of linetype pattern is fixed on print out. It's even shown wrong in Print Preview. You can notice this when zooming in and out in Print Preview, it will change relative to the drawn objects. This is a known shortcoming. That's why I have made that linetypes.pdf, as a reliable reference. That's how it always will look like on paper or in pdf. The size of the dash in dash-dot is about 12mm. Still seems to be longer in your pdf. Don't know.

 image is not in the same position - far off? For me Print Preview is reliable in this respect. There is an issue in windows version that the printout has an offset of about 3.5 mm to the right and to below. Also if you use an external pdf printer, but not if you use the built in pdf - export.

You may provide the file here for examination.

dellus wrote

The size of the dash in dash-dot is about 12mm. Still seems to be longer in your pdf. Don't know.

ok now I understand, my line is 16mm long, but is divided into two 8mm line.
about the position of the image: when I start the print preview, the image is bigger, to fill the paper, and manually I set the scale 1:1.
After that, if I print with a PDF printer, the image appear in the center of the paper. But if I export as a PDF, appear as in the image that I've posted before.

This is the file.
Piastra.dxf

Thanks


P.S. mine is not windows version, I'm using Debian

For me your file worked all right, centered to page, in Windows and Linux. The only reason I can imagine is you have been in Print Preview, the drawing was not centered there, you leave Print Preview and then do export to pdf.
 Stay in Print Preview, after having positioned the drawing there, while exporting, to ensure the expected result.