Dimscale Zero

I notice that in AutoCAD 14, exiting the Dimension Style dialog box often
(and for no obvious reason) resets the Overall Scale factor (Dimscale) to
zero.

A lot of my lisp routines use the current value of Dimscale to perform some
mathematical function, usually division. When Dimscale is zero, the
routines crash out with a 'Divide by zero' error.

I have added a 'Dimscale Zero' error check to my lisp routines now, but my
question is, under what conditions would the Overall Scale factor (Dimscale)
ever be zero? Is zero ever a valid setting?

 

From R14 Help Files:

********

Type: Real
Saved in: Drawing
Initial value: 1.0000
Sets the overall scale factor applied to dimensioning variables that
specify sizes, distances, or offsets. Also affects the scale of leader
objects created with LEADER.

0.0 AutoCAD computes a reasonable default value based on the scaling
between the current model space viewport and paper space. If you are in
paper space, or in model space and not using the paper space feature, the
scale factor is 1.0.

sizes, and other scaled distances to plot at their face values.
DIMSCALE does not affect tolerances or measured lengths, coordinates, or
angles.
********

 

Yes, I had read that.

What I couldn't comprehend was under what circumstances would 0 (zero) be a
valid Overall Scale factor for a drawing.

 

I've tried messing with it set to zero and switching between model and
paper space with a viewport and, so far, have not sussed what's what!

I thought that with it set to zero, then dimensions in model space would
be automatically adjusted, when in a paper space viewport, to suit the
zoom factor, thus avoiding the dimension characters becoming giants.

Hmm.

<FX> Waiting for someone else to chip in...

Brian.

 

That will work as expected if you dimension while in the paperspace
viewport. If you dimension while in model space and then switch to
paperspace at some scale other than 1, you have to update all the
dimensions.