Drawing a regular polygon board edge

[tracy.wynn]

EAGLE Forum:

I would like to draw a regular octagon as a board edge, but I cannot seem to put together the drawing tools in Eagle that will allow me to do this, short of doing trigonometry on paper to determine the end points of each segment. I have tried drawing a construction line and repeating this in a rotational pattern, but I can't seem to make a pattern of a line in which the point of rotation is the end point of the construction line. It also doesn't seem possible to simply draw a line and rotate it through 45 degrees, or I can't find the way to do it.

Eagle's drawing tools seem rather...primitive? Is the expectation that more complex geometry would be drawn in Fusion360 or AutoCAD? 

[jorge_garcia]

Hello @tracy.wynn,

Welcome to the forums! Agree EAGLE's drawing tools are rather primitive compared to what is available in Fusion 360. If your situation allows, I would recommend drawing that outline in Fusion 360 and doing the electronics there as well. Then you can leverage all of the sketch tools within Fusion.

Let me know if there's anything else I can do for you.

Best Regards,

[tracy.wynn]

Thanks for the quick reply.
So I'll need to learn the Fusion 360 package, as well? That's
disappointing... Not that I have to learn a new package, just that it's a
very inconvenient way of working. AutoCAD has been around for, what, nearly
50 years now? Autodesk couldn't even put some of the circa-1990 drawing
tools into Eagle so I don't have to switch between packages just to draw a
simple regular polygon? Not to mention: I don't really want to buy a full
3D modeling software package just so I can draw 2D shapes with some basic
precision in my native PCB package.

I have to say: this is pretty silly, and it's rather annoying.

[jorge_garcia]

Hi @tracy.wynn,

I apologize, I was under the impression that you already had Fusion. If you have AutoCAD, then just draw it in AutoCAD and then export as a DXF file. You can then import the DXF file into EAGLE. That is probably the easiest way.

The other option would be to do the trig calculations but if you already have access to AutoCAD then the above route would be the best way to go.

Let me know if there's anything else I can do for you.

Best Regards,

[volpe]

Hi @tracy.wynn,

The only problem is to calculate the inner radius of the octagon.

Try this:

1. Draw a line in layer DIMENSION (e. g. 10 mm long, GRID mm):

line  (0 -5) (0 5);

2. Duplicate the line 8 times and rotate by 45 degrees. Startiung at coordinate (0.0 12.0710678119):

PATTERN CIRCULAR 8 45.0 ROTATE (0 0) (0.0 0.0) (0.0 12.0710678119)

The inner radius is 12.0710678119mm.

Now you have the octagon. The pcb contour is not closed due to rounding erros. But, you can easily correct the coordinates manually.

Hope this helps.

Happy Layouting,

Francesco

 

[tracy.wynn]

Jorge,

Actually, all I have at the moment is Eagle, so this is frustrating. I am
learning that Eagle's feature set is such that the package cannot
adequately serve as a stand-alone PCB design suite, except for the simplest
of tasks. At least, that is the case from my perspective, where I
frequently need geometrical tools beyond simple orthogonal layouts with
straight edges and rounded corners. It's disappointing, coming from a
company like Autodesk, that has such a deep history in exactly the kinds of
tools that I need. It leads me to the reluctant conclusion that Autodesk is
not really all that serious about PCB design and are using Eagle as a tool
to drive users to buy the mechanical design packages like Fusion360 or
AutoCAD. Those appear to be very powerful packages, but I don't really
*need* that sort of mechanical design power 95% of the time. I need simpler
tools. For example:

1) Snap tools beyond simple snap-to-grid: Snap to endpoint, snap to center
2) Better arc definition tools: Define by center/radius/sweep, define by
endpoints + sweep/radius, define by 3-point
3) Line definition by endpoint and angle with another entity
4) Better rotation tools: select object(s) to rotate, define rotation point
(with snap capability), sweep angle graphically, or by command line
definition.
5) Movable origin (I know that Eagle allows you to define a mark point
against which you can dimension, but it isn't the same, and a true movable
origin is better when exporting to fab files.
6) Better transitioning between imperial and metric units
7) Measurement tools capable of reporting distance, angle, radius/diameter

These are all relatively basic functionalities, all available in CAD 35
years ago, and it's not like adding them will allow me to substitute Eagle
for AutoCAD. I can do many of these tasks on paper, with trig, but it's
2023; I shouldn't need to. I don't understand why Eagle hasn't adopted any
of them, as far as I can tell. All I wanted to do was draw a regular
octagon...

[volpe]

@tracy.wynn 

My suggestion is with EAGLE.

[tracy.wynn]

Francesco,

Thank you for the reply, Yes, I can calculate the necessary endpoints, and
may have to do that, in the end. I appreciate the suggestion and guidance.

On the other hand, it's 2023 and Autodesk is a world leader in CAD
software. I was hoping I had just overlooked a feature, or something,
because I feel I really shouldn't have to resort to manual calculations (to
ten decimal places 🙂 ) or the command line to draw a regular polygon. That
appears not to be the case. C'est la vie, I suppose.

[volpe]

I am using EAGLE since 1991 or so in the Version 2.6 under DOS 😉

Ten decimals are only for testing, if the polygon will close its contour. Remember, PCB manufacturer cannot make a PCB with this tolerance. So, just tweak the endpoint coordinates to 0.1mm precision and everything will be fine.

[volpe]

@aawwais31 

Try this:

1. Draw a line in layer DIMENSION (e. g. 10 mm long, GRID mm):

line (0 -5) (0 5);

2. Duplicate the line 8 times and rotate by 45 degrees. Startiung at coordinate (0.0 12.1):

PATTERN CIRCULAR 8 45.0 ROTATE (0 0) (0.0 0.0) (0.0 12.1)

The inner radius is 12.1mm.

You maybe have to tweak the start and end point coordinates.

Refer to my post 06-21-2023 11:52 AM

Happy Layouting,

Francesco

[Thorsten.Muehlke]

Hallo tracy.wynn,

with a complex contour for the eagle dimension layer.
It is advisable to use the *.dxf import function.
Here the contours are always closed.

greeting
Thorsten

[volpe]

Hi @Thorsten.Muehlke,

That is true and a good way to do the job.

My suggestion was if there is no other program available to draw the contour and export it as DXF.

Happy Layouting,

Francesco

[wk0189713]

Would you be willing to use a different CAD program if it meant being able to draw the octagon more easily?

[tracy.wynn]

Thanks for your reply. I understand the focus of Eagle, and I did
eventually solve the problem by simply switching over to Fusion 360 and
sketching/importing the board outline there. Eagle's focus on schematic
capture and PCB layout is *so* focused on electrical design, however, that
it assumes a rectangular PCB outline from the very start. Then it limits
the drawing and construction tools, making it quite difficult to extend
very far beyond that initial assumption without resorting to external CAD
tools. To me, that limitation is frustrating. PCBs are not always
rectangular, and adding a few 2D CAD drawing tools (from a company that
basically invented most of them) doesn't seem to me like it would be a
problem.

[loodgieterrotterdam3]

Net zoals bij een<a href="https://spoed-loodgieter-rotterdam.nl/riool-ontstoppen-rotterdam/">afvoer verstopt Rotterdam</a> , verwacht je een simpele oplossing, maar loop je tegen onnodige obstakels aan. Hopelijk maakt Autodesk het tekenen van basisvormen in EAGLE eenvoudiger

[tgraphyco]

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[livirafashion]

I totally understand your frustration—EAGLE’s drawing tools can feel limiting for complex shapes like a regular octagon. What worked for me was using the POLYGON tool to manually place vertices at 45° increments or drawing one side and then rotating it repeatedly with the ROTATE command. Grid snapping really helps to maintain accuracy, and assigning the shape to the Dimension layer ensures it’s treated as the board outline. It’s interesting how precision matters in both design and presentation; for example, a well-structured layout in fashion makes a huge difference, like in this sabrina dress collection, which demonstrates elegance through clean, thoughtful design.

[am2store]

Hai ragione, dover passare per Fusion 360 solo per disegnare un semplice ottagono sembra un eccesso. Per operazioni così basilari ci si aspetterebbe strumenti più intuitivi già in Eagle. È un po’ come quando cerchi un Costume bagno uomo: dovrebbe essere una scelta immediata, senza passaggi complicati. Speriamo che Autodesk semplifichi presto queste funzioni di disegno.

[makilrakol]

draw some triangles from the endpoints of the base side and the points marked in the video. u can then calculate it by simple trig https://100001.onl/