Where to dimension?

[nialb]

Hi All, and a Happy New Year

In which view should I dimension? Okay, let me explain ...

I draw in model space (AutoCAD 2005) and create a named view. I then create an ISO A0 template in paper space and bring my drawing in using a Viewport. So far there are no dimensions. I scale the Viewport to suit and then I lock the display. NOW I dimension in paper space as the text height is predetermined by the ISO A0 template, i.e. 3 mm text height.

However, according to my book on AutoCAD (Mastering AutoCAD 2005 by George Omura) there is reference to scaling dimensions to suit the eventual print size. This would infer that the dimensioning should be done in model space.

So what is the correct method? Scale text height for dimensions in model space or do all dimensioning in the page layout view (paper space)?

Thanks

Nial

[SLW210]

If you will search on here for Dimensioning in Modelspace or Paperspace you will get a variety of answers, even some that do both.

Modelspace or Paperspace

[Alan Cullen]

nialb,

Welcome to the forum. You have just asked probably the only question that really has no answer. The only thing I can offer you is a cut from our soon to be launched FAQ:

I have no idea how this will come across. The Boss, has been playing with this, so here goes......

Do I dimension in Model Space or Paper Space?
This issue is one that is more about personal preference. Dimensioning should be done in whichever area is more comfortable.

Those members on this forum who recommend dimensioning in Paper Space do so for the following reasons:

• The model stays clean of lines.
• It eliminates the need for hiding dimension layers in different views.
• With associated dimensions turned on there is no worry about the scaling aspect of the drawing.
• If drawing in 2d, the points stay associated, so if an object is stretched the dimension goes with it.

There would be just as many members who prefer to dimension in Model Space for the following reasons:

• Changing the scale of the viewport leaves the Paper Space dimensions out of position.
• Stretching or resizing an object in Model Space leaves the Paper Space dimensions out of position.
• Moving a viewport to another location in Paper Space leaves the Paper Space dimensions out of position.

However, the above reasons for dimensioning in Model Space are negated if the dimensions are associative.

To make dimensions associative go to Tools->Options->User Preferences and tick Associative Dimensioning, Make new dimensions associative.




Associativity of dimensions is also controlled by the system variable DIMASSOC.

The settings are:


0 - Creates exploded dimensions. There is no association between the various elements of the dimension. The lines, arcs, arrowheads, and text of a dimension are drawn as separate objects.

1 - Creates non-associative dimension objects. The elements of the dimension are formed into a single object. If the definition point on the object moves, the dimension value is updated.

2 - Creates associative dimension objects. The elements of the dimension are formed into a single object, and one or more definition points of the dimension are coupled with association points on geometric objects. If the association point on the geometric object moves, the dimension location, orientation, and value are updated.

It is considered by many members of this Forum to be bad drafting practice to explode dimensions.

The check box Make new dimensions associative can only set variable values 1 or 2. Ticking the check box sets the variable value to 2.

In formats previous to AutoCAD 2002, the variable for associative dimensions is called DIMASO. This can be set to OFF or ON DIMASSOC variable.

If a drawing is saved back to a format previous to AutoCAD 2002, the setting of the DIMASSOC is saved. When the drawing is opened in AutoCAD 2002 or a later version, the settting is restored.
If a drawing that was created in an earlier version than AutoCAD 2002 is opened in AutoCAD 2002 or a later version, the DIMASSOC variable takes on the value of the DIMASO variable.

[nialb]

Thanks for the replies chaps. I am in the process of changing over to AutoCAD from FastCAD (for work related reasons but FastCAD is still my program of choice ) and although the transition has been fairly painless there are one or two conventions in AutoCAD that take a little getting used to. I imagined that for the past two months I had been doing things wrong

It seems to make more sense to dimension in paper space as the text height is always correct irrespective of the scale factor, but that's just my preference.

Nial

[Alan Cullen]

Sometimes, I have to ask myself, why do I bother.

[SLW210]

Sometimes, I have to ask myself, why do I bother.

You bother, because some newby reading this later will get sorted and not ask this question, Maybe.

I think it goes back to one of the previous threads on this. Some disciplines just prefer one or the other it seems. Just to let you know Alan, I am currently working on the Dims in Model, seems much easier for Mechanical Drafting (Draughting?) now with 2008.

[Belianis]

...
It seems to make more sense to dimension in paper space as the text height is always correct irrespective of the scale factor, but that's just my preference.

Well, you can always change text height in all your dimmensions (doesn't work on exploded DIMs!) by changing 'Text > Text height' in dimmensioning style that you've been using in drawing (accessed from DIMSTYLE > your dim style), it works perfectly for me, since I'm doing the process in model space and in most cases I'm sure at what scale I will later plot. But as you said, it's personal preference

[nialb]

Sometimes, I have to ask myself, why do I bother.

Have you misunderstood me or something? Why the angry glare?

I said thanks for the input and then I merely confirmed that I thought that dimensioning in paper space seemed a more reasonable way of doing it (in my opinion).

[riga]

Have you misunderstood me or something? Why the angry glare?

I said thanks for the input and then I merely confirmed that I thought that dimensioning in paper space seemed a more reasonable way of doing it (in my opinion).

Nobody gonna get angry here, you just touched (as stated) one of the most controversial issue concerning Autocad.