control accuracy aligns

[esse09]

Hi.
I wanted some light on the command line... I use it very often, but I noticed that it creates problems in the drawings, because (in my opinion) it always aligns a bit approximately and after a while I begin to have quotas of type 150,034471239 mm...
I press that I never design "on view", always active vegetable garden, snaps activated typically medium, fine, center, knot, dial, intersection + others on need.
Does this command have a precision feature? Can you increase?

Thank you.
Andrea

 

[GP.]

Hi.
...after a little start to have quotas of type 150,034471239 mm...

the reasons are other, if the objects are not scaled in the alignment phase maintain the original geometry.

However, it proves that it is not at an exaggerated distance from the origin of the bird, in this case it could arise some problems, but not only with alignment.

 

[esse09]

I'll never stop them, because I'd change the size, right? They don't have to change, just align.
perhaps on the distance, I never thought about it, the design on which I am working now makes 120000 x 340000 mm from the point 0.0

 

[Cristallo]

the problem lies in the nature of the processors, which can calculate and represent numbers with a finite number of bits (32 or 64).
the more you distance yourself from the origin, the more you use a large number of bits to represent the whole part and the less they remain for the decimal part.
of course an approximation (imperceptible) on the first command, becomes gradually more perceptible if repeated on the same object (or perhaps on sequential copies of this).http: //translate.google.it/transla...1/more_on_autocod.html&ei=eziueydl4fm4qs4cydq This gives you an example of what he's talking about.
If it is not strictly necessary to work so far from the origin, you should move everything closer to the origin of the axes.

 

[esse09]

Thanks for the article, interesting. I knew it was necessary to approach somewhere. .
However, it's not so much a precision problem, a few thousandths or a millionths of a millimeter on a structure of certain dimensions... But the fact is, then to quote forces me to round the quotas and makes it difficult to detect errors.

Thank you for your help.

 

[Cristallo]

Please, come on. But for me, for example, it's not a question of quotation. It's a mental fact.
If I design a 115.45 thing must be 115.45, because geometrically, I make my calculations. . .
I do not admit that a distance has a approximation, because I build, on the elements that are present. And if they're going to get away... I care.
no longer becomes a technical design.. becomes a painting, understood as painting:wink:

 

[esse09]

Yeah, I agree, but this perfection, I think we'll never... We trust in safety coefficients :tongue:

 

[Cristallo]

:36_1_13: You seem to me the trick I work with.
tolerance, safety coefficient... you put them on. I'll take my mistake to zero.
so... downstream there will be those who take care to get into play the tolerances and safety coeffs :36_6_3:

You're kidding.

 

[Legs]

I think it's really too much to say.
try to use, instead of align, the normal shift and rotation commands (with reference).
if the error persists is the fault of autocad but it could also be a mistake related to a bad use of the command. to say, maybe while believing to correctly select the points can happen to select a very close point like that of a retino etc.
Maybe try to use a small set of remarkable osnap points or even zoom on where you go to select so as to avoid these errors.

 

[esse09]

I think it's really too much to say.

I am now working on a drawing where, wishing to verify this, I avoided copying anything from other dwg, always drawn to the tenth, avoiding the iron command, and with few active osnaps.
All right, then I started to align and the odds started to squirt badly:/
In addition, since sometimes I carry inventor profiles as blocks, with these measures a little particular ends that I find then problems in putting constraints

 

[GP.]

autocad version? installed service packs?

attach a dwg that contains the original object, its aligned copy and the "shuted" odds.

 

[esse09]

I installed autocad through the factory design suite completed 2013
service pack 1

I'm sorry if I don't tie your drawings, but I can't spread them.

 

[GP.]

...excuse me if I don't attach your drawings but I can't spread them

I understand that, but it is not necessary.
If you care about the problem, you can try to replicate it with random lines, even if it is not said that here we can solve it.
See you.

 

[esse09]

You've already given me some interesting ideas. In the next job, I'll see what happens.
Thank you.