Expert: Bob - 3/7/2011

Question
Using AcadLt2011
Civil, Structural and Petrochemical Engineering Field
Need to break a line at an intersection using a macro in lieu of having lisp routine ie adapt the present break command.
Would like to select a line to break at an intersection without using 'first point and second point'- this is for our piping people who need to show lines that cross each other.

Answer
Hi -- I am not in your field, and I do NO macros or lisp, but what I CAN suggest:

(easier if you made clear that the piping is two lines, and whether it comes in multiple sizes)

Do I assume that you draw piping with a single line?

If the pipe being crossed is two lines, I would always use TRIM, hit ENTER to make everything in the drawing a cutting edge, then trim out all the stuff I did not on ONE easy command. This avoids having a special command for the one which is going to be broken.

Alternatively, I might use BREAK AT POINT to make one break, then clean it up with the grips or TRIM. I would do all the breaking and all the trimming at the end. Breaking lines twice at intersections does not work cleanly.

If they are all single lines, I would use SEND TO BACK and never trim or break them (I dont have LT2011, but that should be in the right-click menu) There is NO reason to break single lines if a gap is not needed. If they are polyines, as they should be, you lose the measurement by breaking.

If they are double or single lines, and you wish to show a gap at either side of the pipe being crossed, that is harder. For that, I might make a block of a circle containing a square (sqare is size of pipe, circle is size of gap), then draw everything, then insert the block as many times as needed, TRIM around it to create the setbacks, erase the blocks. (alternate: offset the pipes, trim, erase) If LT2011 has dynamic blocks, one serves all sizes.

http://en.allexperts.com/q/AutoCAD-1029/automatically-break-lines-cross-1.htm
Here is a reply to someone who needed a CONSTANT SIZE GAP.

Last, if people are doing piping all day, they might better have the full software that draws piping properly, rather than messing around with lines. I am not there to tell.

Bob