Why does AutoCAD keep changing length/values and how do you deal with?

[leander.gaeb]

For example, I draw the property line and need to keep a 5m distance to the street and a 3m distance to all other lines, so I use the offset tool twice and draw the outline of the building using the edges and the intersections of the offset-lines. When I return at a later point the distance has shifted by a tiny fraction to something like 4.99974m instead of 5m.
Not a huge difference but it can add up if it keeps happening and I keep using the outline as a frame of reference.
So, is there any way to prevent it (aside from using parametric constraints on EVERYTHING) and if not, how do you deal with it?

[RobDraw]

This can happen if you are far from (0,0).

[imadHabash]

Hi,

In addition of what mentioned in the previous post .. you can from UNITS command change the Precision to 0,00 .

[leander.gaeb]

So I can just not stray to far from base 0,0?

[Kent1Cooper]

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@leander.gaeb wrote:
So I can just not stray to far from base 0,0?

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You can stray pretty far, within reasonable sizes of real things, before it starts to become a problem.  But we've seen people with similar problems post drawings with coordinates that were farther from the original than the diameter of the solar system -- I remember seeing values in the range of 10-to-the-14th-power....  How far away are you?

[leander.gaeb]

Between 40 and 500?

[cadffm]

Lower xyz than +/- 1.000.000 is perfect.

(Note, they are talking about 0,0 wcs - doesn't matter your current ucs)

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My question is another one: Your sample with length 5.

Are you sure that the line was ever

5 long?

I guess the line wasn't 5 long and you didn't test it directly.

?

Another case: Between creation and your length check (4.99..).

Wasn't there a scaling since you created the line.?

[RobDraw]

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@leander.gaeb wrote:

So, is there any way to prevent it (aside from using parametric constraints on EVERYTHING) and if not, how do you deal with it?

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You seem to be under the impression that the program is not accurate. That's very far from the truth. Something is happening on your end to cause this. I thought it might be the distance from (0,0) but that doesn't appear to be the case.

Please provide a file and the steps you take to reproduce this problem.