Why does Acad think I want a 45 degree rotated linear dimension whenever I use the DIM command?

[eballGN5HQ]

So, I wouldn't say I'm an expert in Autocad, but I can eventually figure out most trouble-shooting problems. 

But this one has totally stumped me.

All of a sudden, Autocad is forcing a very specific kind of dimension on ordinary lines all the time. I use the standard DIM command, but the dimension it generates is anything but. It seems to be a rotated linear dimension with an angle of 45 degrees. Only, I want to know how long my dang line is, not how far apart two parallel lines extending from both endpoints at 45 degrees are! 

My main problem in figuring this out is that I have no idea how to go about doing it if I wanted to. I've looked through every single system variable starting with DIM and none of them are causing it.

I just want to know if anyone else has ever had this problem.

BTW, it was just in that one drawing, too. Other drawings are fine, even with every setting seemingly exactly the same. But I deleted everything I possibly could from that drawing except one solitary polyline, changed my dimstyle and text style to standard, but still it persists! Interestingly, it only happens when trying to dimension with the UCS rotated about the x axis 90 degrees. At the home UCS orientation it works like normal.

So, if anyone has seen this before, I'd really love to know about it.

[cadffm]

Hi,

DIM is a magic youtubeinstagramtwitterteenagecommand, if you want to get XYZ, use XYZ

and not a command which trying to read your thoughts!

The real DIM commands (to create a dimension) works without this issue.

The problem is: DIM doesn't work well with objects with a normalvector different to 0,0,1

(check the properties of your line and a new line drawn in WCS, use command LIST and compare the results)

BUG in DIM command. Tested with AutoCAD 2020.1.4

If you don't want to add dimensions, just to know the length, check the length in properties palette .

[eballGN5HQ]

I'm not trying to solve a problem here--dimlinear still works fine, it just takes longer. No issue getting dimensions. What I want to know is how this is happening in the first place, out of sheer curiosity. It's never happened to me before or since this one drawing, so I know it's not just _dim being weird. It's one hundred percent some kind of setting being on, or something. It's gotta be. In a new drawing, replicating the steps taken exactly to get the weird dimension results in a totally normal dimension. So regardless of DIM not working well with objects like this one, why is it that even recreating this very object in a different drawing does not produce the same result?

[pendean]

>>>...why is it that even recreating this very object in a different drawing does not produce the same result?...<<<
@eballGN5HQ Most likely you have something else going on that you've not observed yet: share with us over here those DWG files, faulty and not-faulty for someone else to help you compare and find the culprit.

[eballGN5HQ]

Actually, I was totally wrong about that. I didn't correctly determine the UCS I was using, so when I tried to recreate it, it naturally failed. Using the same UCS relative to the WCS will result in the same thing occurring.

Still, there's a lot more weird stuff I discovered. Like, if you force off the associative property of all dimensions in the drawing by changing the value of the system variable dimassoc, attempting to dimension the same line will result in a rotated linear dimension of something like 28.33 degrees instead of 135 degrees, or something like that. If it isn't parallel to one of the axis, DIM works fine. Very weird.

So while I was indeed wrong about just how rare this phenomenon is, it remains no less mysterious in my mind. Why does Autocad do this? How does it pick the angle? What code is acting up here, exactly? Was this intended to be a feature at some point? Why does the DIM command have the power to do this in the first place? 

For every answer, there are only more questions.

[pendean]

AutoCAD only does what you set (or miss setting), nothing more: unless you want to post some solid reproducible issues we can all do in our own files (or in your own files) all the time on demand we'll just have to chalk it up to a missing setting(s) somewhere.

Glad you fixed your first issue, that was going to be my guess at the cause too.

[cadffm]

The DIM function doesn't work well with negativ coordinates in ucs,

you can read a bit more in another Thread.

Start a support case as bug report!

Show your problem and also add my link to your case.

https://forums.autodesk.com/t5/autocad-forum/dimension-won-t-snap/m-p/8405308#M957450

It is a programmer mistake in the program.