Topic: Why isn't 1:1 the same in millimetres as it is in Inches?

[hudster]

I noticed this when I was plotting an architects drawing, if the setup is in inches, you get a different size when plotting at 1:1 than when you do when you change the units to millimetres.

For example when I have an A1 drawing set up as millimetres 1:1, when I do a plot preview I can see the whole sheet.

Switch the units to millimetres same drawing sheet, set to 1:1, when I do a plot preview now I can't see any of the sheet.

Surely 1:1 is 1:1, whether it's millimetres or inches?

[daron]

Which one is inches? Not that I have any idea for a solution.

[CADaver]

Surely 1:1 is 1:1, whether it's millimetres or inches?

In one you have 260 units X 200 Units and you calling those units MILLIMETERS in the other you're calling those same units INCHES.  Where the first will fit on a letter size sheet, the second would require a sheet of paper larger than most apartments.

[Keith™]

Well, you have to think about the size of the paper you are plotting on. That is the key here....

For example:
You have a drawing that is setup to plot on ISO A1 paper (594mm x 840mm)

Now you draw an object in inches say 33" long when you set the plot to 1:1 it go from side to side to cover the whole page.

BUT

The same drawing drawing in MM you would have to draw the line 840mm to have it cover the whole page.


Remember the scale factor is relative to the drawing itself not the paper. The scale factor converts the drawing to the paper size so if you have a drawing that is 33mm and you try to plot 1:1 on a page that is 33" the scale will be wrong, it will be 1/25.4 of the actual drawing.

To plot 1:1 you would have to plot 1:25.4