Units

I made some drawings the other day of some building elevations. Everything looked just fine to me. Then one of my co-workers called me and was complaining that many of the lines in my drawing were not parallel. All of these lines were either parallel to the X or Y axis. I drew most of them by using

When I drew these lines my precision was set to 1/16 which should be fine for construction. However, my co-worker was using 1/256 precision. So I changed my precision to match and sure enough the properties of the lines started showing the lines were drawn at 89.00023 degrees, or 179.00067 degrees. This was most disturbing to find because it means I have either a problem in my drawing method or changing the precision will skew my otherwise parallel lines.

It sounds like either SNAPANG was set off of zero slightly or the UCS was rotated about the Z axis.

There is a proven bug within autocad where when lines are mirrored they are sometimes not perfectly parallel.

This happens to me a well when my units are set to 4 decimal places and when you change it to the max range it will be slightly out. What happens in my case is when I sometimes use old data that was not drawn very well and the problems multiply. Also sometimes when using Polar it can come in. I have also found when blending a radius using the fillet command between one rad and a line Autocad can work this out slightly wrong and you cannot polyline so you have to use the TTR circle command to do this instead. These things don't happen a lot but when they do it is a lot of fixing up to do on your drawing.

It will be interesting to see what others do to fix this issue!

Had the same problem in the past, so have gotten in the habit of turning ortho on when drawing lines that need to be horizontal or vertical. Seems to have fixed it for me.

Thought this last upgrade to Autocad had given me some crazy abberration though. When I'm working seriously, I always have music playing. Got hundreds of songs loaded on the hard drive so I don't have to listen to commercials and some dj's inane babble. At any rate, i noticed after this last upgrade, almost every time I hit F8, a different song would start playing. Just interupt whatever was on with another. Got to be very annoying. Did some digging around, could find no one else that had ever experienced it. Then one day, I figured it out. At about the same time I upgraded, I had purchased a new keyboard. A Saitek Cyborg to be exact. It has lots of cool features, among them a row of membrane keys above the F keys to control the media player. Everytime I reached for the F8 key, my middle finger was inadvertently hitting the fast forward button on the media player. Just gotta be smarter than the stuff you are working with I guess.

Details we get will have this aberration sometimes. A line that should be horizontal/vertical isn't, and there's no apparent reason.

My solution is to draw a base line that is horizontal or vertical to whatever precision I need, usually 4 decimal places. In the properties for the line, the Delta X/Y value will be 0.0000 and the angle will be some multiple of 90.0000. Any line that is offset from, or drawn perpendicular to, that line has to be parallel or perpendicular to it. So lines that should meet at a corner will meet.

In you case, I would suggest drawing an absolutely straight line, another one perpendicular to it, check both, and then copy/offset those to get all your other lines. For instance, draw one line horizontal, draw a second perpendicular, move the second to the end of the first, then copy both to the opposite ends. That gives you a perfect rectangle. If your original line is off, using