Does Having Lines on top of each other affect the line wight when printed ?

[OSOJo]

Alright, I recall when I first learnt Autocad 2 years ago, I was told to pay attention not to draw two lines on top of each other. So I developed the habit of trimming everything and stressing over any lines being or shapes being drawn on top of each other.

But now, I have been watching these "proffesional" autocad drafting and drawing, and the tutor makes no comment on, and does draw lines on top of each other without deleting or cleaning anything, so it made me wonder.

Does it afffect the line weight of the fial print / out put ?

Thanks a lot, in adnace,

[jggerth1]

that depends ---  if Lines Merge is set in in the PC3 for plotting, the resultant on the hardcopy will be a combination of all the lines that are coincident.  If LinesOverwrite is set, only the top line should be plotted.

Generally speaking, unless there's a good reason to have coincident lines, then it's a good idea to avoid them and maintain clean drawings.  Often, there are good reasons, equally often it's simple sloppiness.

[Kent1Cooper]

I don't think it matters now, except for your own preferences, and in the case of graphic considerations such as not having a continuous object overlay one with a non-continuous linetype if you want the gaps in the latter to show.  Years ago when plotters that used actual ink pens were common, it was a good idea to avoid it because a pen could clog when drawing continuously along another ink line, rather than on the clean paper/mylar surface, just passing briefly over intersecting lines already drawn.  But I doubt there are many pen plotters left these days.  I agree with JGerth that there are sometimes good reasons to have overlapping elements, such as when object-specific lengths and/or areas are important [for such things as total length of pipe runs, etc.] and would be adversely affected by [for example] Trimming out pieces of things where they overlap other things.

[OSOJo]

The only reason I asked is that, it definitely makes architectural drafting much easier, if you just draw above the construction/grid lines.

It's only a matter of fast proffesional drafting, where you really want to be fast, and not worry about columns overlaying walls, an edge of a certain rectangle being on top of a certain line, etc.

So is that a good enough reason ? If it does not affect the line weight, then yes it would make drafting faster to not worry about it

[jggerth1]

Fast is good, being right is more important, and one thing to consider is how the next person down the design chain will be able to work with coincident linework.  If separated by layers, so he can readily turn off what's not needed for his part of the project, then fine.  I certainly would NOT advocate deleting or breaking a structural grid line because my wall line was on top of it -- they are different things, and both matter.  Always assume that your drawings will be reused and repurposed, and as part of being professional, view them on the basis of their ability to be adapted to another part of the design chain.  Or the client's future facility management needs.

Let me correct my earlier statement -- Lines over write can have problems plotting, if the underlying linework is plotted with a heavier lineweight than the top lines.  you'll only see the top line, but the plot will have the fat line plotted unerneath the thinner top line.    (I just got bit by this one this morning -- using translated DOT details, that had white arrows boundaries under red arrow boundaries.  Couldn't visually see the white, but the arrows were plotting as huge black blobs..... PITA.  If that's a detail I'll need more than once, I'll have to invest the time to make it a decent ACAD drawing instead of a conversion (linework instead of text, consecturive short lines instead of a dash line type, etc.  The thing looks like an HPGL to DWG conversion....

The other place that lines over write can cause problems is a screened line over a screened hatch, a 50% line drawn over a 50% screen hatch is pretty much invisilbe on the hardcopy....

[OSOJo]

"Let me correct my earlier statement -- Lines over write can have problems plotting, if the underlying linework is plotted with a heavier lineweight than the top lines"

Oh god, your earlier statment conforted me a bit, and made me realize how uptight I was about lines overlaying haha.

Well maybe I should keep the same mindset about it.

I am just baffled how this paid DigitalTutors course would not point it out. He was drawing a lot of overlaing lines, and also drawing rectangles (for columns) with one edge exactly overlaying the wall. Yet in the same breath talking about how important line weight is.

[maxg]

Bringing this old thread back....I have a drawing that needs to show less than precise lines at a scale of 1"=600' for a ~450 acre site. I have three or four areas that but up against each other that i would like to just overlay the boundry lines on top of each other to make sure they match up perfectly. What I have found to be very time consuming is to try and account for linewidth once plotted. How to I tell ACAD to plot both, but next to each other?

[jggerth1]

You want to plot lines that are geometrically congruent so they show up side-by-side on the print?  As in parcel lines dividing up a site?

I think you'll be stuck drawing them 'wrong'.  possible offset to either side and delete the original.

[maxg]

Yea, that is the conclusion I am reaching as well. 

Baaaahhh humbug. 

Thanks for the reply. 

[wispoxy]

Don't understand these large replies.

Simple Answer... No.

[jggerth1]

Simple answers are good, except when they are wrong.  Or incomplete.  If an underlying line was a heavier weight than the congruent overlying line, then  the obesity of the bottom line can show up when plotted.

They won't add, eg a 0.50 line and a 0.25 won't plot at 0.75mm. but will plot at 0.50mm.

If the underlying line is plotted at a lighter or the same weight as the yop line, no problem.  it's only the reverse situation that can cause suprises on the hardcopy.

[wispoxy]

The answers can go many ways, not specific enough.

But when you stack 10 default 0mm lines on top of another, its not going to change the thickness.

The thickest line will show on a stack. Simple as that.

Default Simple Answer, no. The thickest line on a stack will always show unless on def point.