Moving groups of objects and blocks introduces tiny errors!

[inkychris]

I'm drawing an audio series block diagram. With this I have horizontal paths leading into vertical busses. If I move the horizontal parts just up or down, more often than not, autocad will somehow distort the objects such that everything is off grid by 10,000ths of millimeters! Despite these having horizontal, vertical, perpendicular and parallel constraints. Copy seems to have the same effect quite consistently.

I'm using infer constraints intentionally. Some blocks have other blocks inside them but this problem occurs even on selections that aren't built like that. I've tried grouping things before moving them, exploding them before moving but every time it's not helped and I've ended up just redrawing that part where I want it...

I've included a before and after of the kind of thing I'm talking about. Sometimes it's all linear but in this particular example it all seems to have twisted which I find near impossible to fix. There is also a dwg of the 2 examples but I can upload my original file if it's not clear from there.

Thank you very much in advance. This has cost me vast amounts of time recently and I can't find anything like it.

Chris.

[Alfred.NESWADBA]

Hi,

first at all, I don't understand what the "autocad errpr.png" shows as error.

But what I see if I open your drawing and run _AUDIT ... there are a lot of errors in the drawing database, and that might be the source of your problem.

- alfred -

[inkychris]

Hi,

Sorry for not clarifying. I moved the assembly vertically with polar snap by an integer value, but the assembly then distorted such that almost none of the points fall on the grid anymore eg in the example where the endpoint coordinate should be (380,530) but instead is (379.9846,530.0135). This would be solvable if they were all displaced by the same amount but it seems to be twisted too.

Thanks for the response,
Chris.

[Alfred.NESWADBA]

Hi,

>> I moved the assembly vertically with polar snap by an integer value

Look to my video, is that what you are asking for? If so you can see in the property window within my video that the insertion points are also on rounded values after I moved the object.

Or am I doing anything different to you (e.g. having disabled dynamic input).

- alfred -

[inkychris]

The separate part you demonstrate on was how the block was supposed to be position, the problem I'm having is with the blocks above that. They were originally on rounded coordinates but after moving them by an integer value, they changed to very slightly and the vertical/horizontal constraints applied within the blocks seem to be being ignored.

So before I used the move command on the block above, it's coordinates were say (300, 600), when I moved it down 30 with the polar input (0 degrees) it became (299.9846, 570.0154) instead of the expected (300,570). The main problem with this however is the fact that the supposedly constrained points on the block elsewhere are not also displaced from their expected coordinates by (0.0154,0.0154).

I'm will try disabling dynamic input. Could it be something to do with the way the blocks are constrained to each other?

Thank you very much for your time!

Chris.

[nestly2]

When the angular precision is turned up (UNITS command) it can be seen that many of the blocks are rotated slightly.  It's not clear to me whether this is a result of the problem you've described, or the cause of the problem you described.

Can you attach another drawing where everything is aligned the way you want  (before moving) the constrained objects.

As a side note, IMO, it's neither necessary nor desireable to constrain everything in the drawing  (especially not the objects inside a fixed block).

[inkychris]

I've attached my original drawing. The error can be produced by selecting the penultimate row between all the vertical lines (circled red) and moving it down with polar snap. I typed in 500 for the distance and the lower right X (circled blue in original position) is now not centered on integer coordinates.

[inkychris]

Ok so I found that one of the blocks was made entirely of another block so I exploded it and saved the block and that seems to have fixed the issue. So I'm guessing that over constraining everything was likely the problem?

With that in mind, could you tell me the best way of doing what I wanted instead of constraining and making blocks of blocks etc? Would grouping perhaps be a better solution?

Thanks again,
Chris.

[nestly2 · Accepted solution]

Even after cleaning up the blocks and removing all the constraints within the blocks, I'm still getting unexpected results.  In the animation below, the objects on screen were WBLOCKed into a clean drawing.  What I find odd is that if I include the vertical line in the MOVE selection, the objects rotate and move unexpectedly, however if I exclude the vertical line from the selection and let the coincident constraint "drag" it along, everything works fine.

Alternately, if the Horizontal constraint is removed, everything also moves as expected, so I would classify this as AutoCAD behaving badly, not necessarily a matter of being over constrained.

[inkychris]

Thank you very much for your help. I was hoping I was just doing something wrong but alas! Perhaps it should be reported as a bug or something? I'm not entirely sure how to do that if you think it might be worth doing.

Thanks again for your help.

[nestly2]

If you are on Subscription, log into your account and submit a Support Request.

If not on Subscription,  go to the Bug report guidlines, then continue on to the Feedback submission form to describe the issue.

In both cases, I'd include a link to this forum topic.

[inkychris]

Thanks for that. I've submitted a bug report pointing to this forum topic so hopefully they can look into it.