[Resolved]  How do I edit properties of an arc?

rickford66 wrote:

How do I edit the properties of an arc? I would like to set the

center, and radius, but can't find how. Eagle shows them to me as

read only values when I click properties. Thanks.

 

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You cannot edt the those properties.

In Eagle the arc is a WIRE with curve and  so you can draw arcs using WIRE

and give the curved wire a radius.

See HELP WIRE.

What I often do is lay down a circle as a guide to create the desired arc,

then remove the circle

Warren

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Then I'd have to ask, what's the point of having an arc.  The PCB layout software I acquired in 1992 allowed me to set the center of the arc, the start degrees and end degrees.  If I want to make a number of large loops around the outside of a pcb, this sort of setup is ideal.  It looks like the arc in Eagle is pretty useless if I have to use a trace instead every time.  Why do they provide such information in the properties if they can't be adjusted?

It appears that I can draw an arc using a command input that will do what I like.  For example, say I want an arc, centered about the origin, that starts at point (5.547, .299) and swings clockwise around to (5.534, .489), I would input the following command line.

ARC CW (5.547 .299)(-5.547 -.299)(5.534 .489)

The ARC command is obvious, as is the CW command.  The first coordinate is the starting coordinate.  The second coordinate is the origin, relative to the starting point.  The third coordinate is the end point.  Note there is no comma between the X and Y of each coordinate point.

On 12/03/13 14:43, rickford66 wrote:

It appears that I can draw an arc using a command input that will do what I like.  For example, say I want an arc, centered about the origin, that starts at point (5.547, .299) and swings clockwise around to (5.534, .489), I would input the following command line.

ARC CW (5.547 .299)(-5.547 -.299)(5.534 .489)

 

The ARC command is obvious, as is the CW command.  The first coordinate is the starting coordinate.  The second coordinate is the origin, as it relates to the starting point.  The third coordinate is the end point.  Note there is no comma between the X and Y of each coordinate point.

 

Yes, you can draw arcs with that command, and if you use one of the

copper layers then Eagle knows that they form traces. I think Warren was

assuming you wanted this to be a signal trace, in which case it's

usually easier to route the air-wire and then make it curved. I've not

had cause to try it but it may be hard to make an arc part of a net.

On 03/12/2013 10:43 AM, rickford66 wrote:

It appears that I can draw an arc using a command input that will do what I like.  For example, say I want an arc, centered about the origin, that starts at point (5.547, .299) and swings clockwise around to (5.534, .489), I would input the following command line.

ARC CW (5.547 .299)(-5.547 -.299)(5.534 .489)

When drawing arcs, using polar coordinates is more convenient.  Suppose

the bottom left corner of your board is at the origin, and you want to

draw an arc rounding the corner off with a 40 mil radius:

    grid mil;

    mark (40 40);    # Set the center of the arc

    arc CCW 10       # start an arc that's 10 mils wide

    (P35 180)        # radius of 35 which is radius - width/2

    (P35 0)          # Sets the diameter- same radius, opposite angle

    (P35 -90);       # Sets the end point of the arc

The radius of 35 is to keep all the copper on the board, rather than

placing the center of the trace on the edge of the board.

If you're drawing the arc on a signal layer (layers 1 - 16), you can add

a net name to it to make it part of a signal:

    arc 'N$1' CCW 10 (P35 180) (P35 0) (P35 -90);

HTH,

    - Chuck

The arc properties allow you to change the name to make it part of a net, no problem.  I think it's weird though that it doesn't allow you to change many of the properties once it's drawn.   You just have to know exactly what you want before you draw it.  Not a big deal though, because it does allow that.  I drew mine and had no problem putting it all together.  In my case, my arcs were about 355 degrees around, so I would have needed to draw at least 2 traces, and figure out their radius such that they both landed exactly on the circle.  Since I am only connecting to the ends in this instance, I prefer the arc.

Thanks for everyone's help.