Need to Have Consistent Arcs in Polylines

[Anonymous]

I'm working on a technical drawing which contains a lot of polylines with arcs. Geometrically speaking, it's a very simple drawing. The line segments are either horizontal or vertical, and the arcs only exist between horizontal line segments. The intent is all the arcs are actually semicircles (180 degrees) with the same diameter (NOTE: diameter = chord length at 180 degrees).

The issue is, I completed the drawing by doing all the polylines/arcs by hand. This has led to lots of inconsistencies in size and shape. This makes the drawing ugly and unprofessional looking (subjective) but also hard to read (objective). I can go through all the line segments and edit the vertices to make them consistently spaced. I can also edit the vertices of the arcs so all of my arcs have the same chord length. However, when editing the "height" above the lines, I can only do it by hand, and it doesn't give me the numerical values I need to even do it correctly by hand (this "height" should be half the chord length to make it a semicircle) and I don't know a command I can use to just change that one parameter. If it was a standalone arc, not as part of a polyline, I know what commands I could use. But those commands don't seem to work for an arc in a polyline. I also need a method that's relatively efficient as I'll have to repeat the steps many times over.

I'm using Windows 10 with AutoCAD 2018.

Background (not necessary to answer my question, but if you're curious):

I'm doing electrical wiring diagrams. The semicircles are "jumps" that show that wires are crossing but not connected to each other. In previous jobs I have used AutoCAD Electrical or Visio to do these drawings, as they can do these "jumps" automatically. However, at this job I do not have access to either of these programs (or ANY add-ins to AutoCAD, only the base package), so I'm trying to find a "cookbook" method to do this as efficiently as possible.

[Valentin-WSP]

@Anonymous,

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@Anonymous wrote:

I'm using Windows 10 with AutoCAD 2018.

However, at this job I do not have access to ... ANY add-ins to AutoCAD, only the base package), so I'm trying to find a "cookbook" method to do this as efficiently as possible.

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Try the Autodesk App Store, there is a particular App that will resolve your issue.

See link: 

https://apps.autodesk.com/ACD/en/Detail/Index?id=8403098009239569515&appLang=en&os=Win32_64

[RobDraw]

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@Anonymous wrote:

NOTE: diameter = chord length

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Isn't this going to be a problem?

[Kent1Cooper]

This would be quite simple with positional SNAP turned on, set to the radius value of your arc segments, both when you draw the straight-through wire Lines/Polylines and draw or edit the Polylines with the crossover arc segments.

[Anonymous]

Valentin-WSP, thank you for the suggestion. I am aware of apps that are available to do this. Unfortunately, this is a work account and I don't have admin access or license rights to install any apps whatsoever so that won't work for me.

[Anonymous]

Robdraw, no not a problem at all. I was just mentioning the natural mathematical consequence of having a 180 degree arc (aka a semicircle). If you have a 180 degree arc, then your chord length (not to be confused with arc length) is equal to your diameter. The diameter is the maximum possible chord length. If chord length > diameter, that would be a problem as that's not physically possible.

[Anonymous]

Kent1Cooper,

Can you please elaborate  on your answer? I use osnap all the time, but that isn't helping me as it's object related. That does make me think, I guess one option is I could use osnap, lay guidelines down, make my arcs, snap them to the guidelines, then remove the guidelines or make the guidelines hidden. But if I could do it in less steps by setting something else up, that would be great.

When you say "positional snap" what exactly are you referring to and how would I set it up in the way you're describing?

[Kent1Cooper]

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@Anonymous wrote:

.... Can you please elaborate  on your answer? I use osnap all the time....

When you say "positional snap" what exactly are you referring to and how would I set it up in the way you're describing?

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Not Osnap.  Some refer to what I mean as "grid snap."  It's the SNAP command, and several System Variables whose names begin with SNAP.  It snaps the cursor location to only multiples of the distance settings.  >Read about it<  

[In the video, before drawing things, I have answered the Legacy option in SNAP with Yes, so that it locks onto grid positions even with no command active, which you can see as I move the cursor around at the beginning.  By default (No to Legacy), the cursor floats freely when not in an operation.]

Sorry my view wasn't wide enough to catch all the typed-in Second-point or Direction and back-to-Line-mode options in drawing the first arc-over Polyline, but I hope you can see what's going on.  In the second one, I drew it plain first, then grip-edit-added vertices on either side of the vertical Lines, and grip-edited the crossing segments into arcs.

If you have things already drawn that do not lie along SNAP-grid spacings, you can turn SNAP On and grip-edit them to do so.  Or if you like, I have a routine [and there are others] that can take all selected objects and force all their endpoints, vertices, insertion points, etc. to the nearest SNAP-grid positions.  After doing so, you would probably need to grip-edit the midpoints of arc segments to make clean 180° arcs.

[Anonymous]

I did try some Grid SNAP settings without a lot of success. I do have a grid set up and my ideal "jump" is 8 grid units wide and 4 grid units high. The problem is, I have issues in the other parts of the drawing. I'm using some manufacturer provided models for the blocks I'm interconnecting. They have internal connection points (that are not vertices, midpoints, or even touching the side) that I haven't been able to get on the grid so far.

That being said, I didn't have the legacy setting on, and when drawing I have made sure to always come out of the blocks on the vertical, and I only do my "jump" on the horizontals. As a result, all my horizontal lines are on the grid, so that helps. But the verticals are not and therefore the vertices I need for the jumps/arcs may not be right on the grid, so they may not be centered right on the vertical lines they are jumping if they are snapped to the grid. 

I'll give it a try though, maybe if I keep trying, I can scale the manufacturer blocks to sizes that line up the connection points with the grid. I may need to put the edges/corners of the blocks off the grid in order to do it, though.

[Valentin-WSP]

@Anonymous ,

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@Anonymous wrote:

 I am aware of apps that are available to do this. Unfortunately, this is a work account and I don't have admin access or license rights to install any apps whatsoever so that won't work for me.

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I'm sure if you ask your Manager or IT Department and explain how this App would facilitate your workload - it will be granted.  Emphasize that it will save time and money.  If they paid for a full version of AutoCAD, tell them to take advantage of its capabilities.  Do not be limited to certain tools. 

Show them the video.

[Anonymous]

OK, so been using Grid Snap. It does the job but REALLY slow. Anyone else, if you can use the Apps, use them. If you're like me and you can't, another tip, turn ORTHO off (F8). With ORTHO on, every move is painful as it will ONLY SNAP either Horizontal or Vertical at a time, not both with ORTHO on, so every vertex requires TWO moves to get on the grid. Once everything is on the grid, ORTHO ON can be helpful, especially if you move a midpoint that's only aligned to one.

Also, if you're trying to move polylines:

If  you try to move it by clicking and dragging somewhere other than a handle, it won't SNAP even with SNAP ON.

BUT, clicking and dragging from a handle does a STRETCH, not a MOVE.

If it's really close to where you want it, and it's already aligned to the grid, you can NUDGE with CTRL + arrow key which will move it by one grid space at a time.

If you have to move it a long distance:

One way is to click and drag a midpoint to move it, then one-by-one align each vertex all over again

OR use ctrl + click on each vertex AND midpoint on the polyline until all are selected, then move from a handle and it remains snapped to the grid. 

BUT both of those are slower than select object, type the MOVE command in, then select the base point, then select the point to move to. If SNAP is ON it will stay SNAPped to the grid. Only reason not to is if you hate typing and want to do it all by mouse.

[Kent1Cooper]

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@Anonymous wrote:

....

Also, if you're trying to move polylines:

... clicking and dragging from a handle does a STRETCH, not a MOVE.

....

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Grab a grip, and hit Enter or Space and it switches from Stretch mode to Move mode.  [And again for Rotate, again for Scale, again for Mirror, and again to get back to Stretch.]