topic Re: POLYGONS in Fusion Design, Validate & Document Forum

POLYGONS

Anonymous — Sun, 28 May 2017 05:39:07 GMT

I am wondering why fusion has the inscribed and circumscribed definitions the wrong way around.

IC or inscribed circle is when the circle is to the IN side of the flat edges.

CC or circumscribed is where the circle is to the OUT side of the flat edges.

Re: POLYGONS

TrippyLighting — Sun, 28 May 2017 11:10:49 GMT

Ha...I never noticed that.

The implementation of the polygon is rather noobish to be honest.

Obviously it it was not understood what inscribed and circumscribed is.

When you draw the polygon, even when you define the dimensions and number of sides and accept with the return key, the polygon remains undefined and has to be dimensioned afterwards, making the designation between circumscribed and inscribed superfluous.

Re: POLYGONS

TheCADWhisperer — Sun, 28 May 2017 12:41:57 GMT

@Anonymous wrote:

I am wondering why fusion has the inscribed and circumscribed definitions the wrong way around.

IC or inscribed circle is when the circle is to the IN side of the flat edges.

CC or circumscribed is where the circle is to the OUT side of the flat edges.

But the design intent (and the result in Fusion) is not to draw a circle.

The design intent (and the result in Fusion) is to draw a polygon.

Note that no circle is left on the screen after using the command (which really is rather unfortunate, especially for odd number of sides - it would be nice to have a construction circle).

Inscribed See #5.

Circumscribed See #4.

Note that these definitions refer to the drawn figure.

It this case the figure is a polygon.

Re: POLYGONS

jeff_strater — Mon, 29 May 2017 16:53:10 GMT

I think @TheCADWhisperer is correct. It depends on how you view it - we chose to view it from the point of view of the polygon. That is, the polygon is inscribed inside of the circle in the Inscribed Polygon command:

Both @TheCADWhisperer and @TrippyLighting are correct - the polygon command is a bit limited. It is a very old command, in the Fusion lifetime. For instance, the suggestion of keeping the circle as a construction curve is a good idea, but this command first came into being before Fusion had construction geometry in sketches! Similarly with adding a dimension for the polygon if you type a value. The polygon command preceded even that! I'll add those suggestions into the backlog for these commands.

Jeff

Re: POLYGONS

Anonymous — Tue, 30 May 2017 11:34:18 GMT

I am aware of the intent of the function however it has been incorrectly labelled on the menus

Geometry. to draw or delineate (one figure) within another figure so that the inner lies entirely within the boundary of the outer, touching it at as many points as possible:

To inscribe a circle in a square.

Re: POLYGONS

Anonymous — Tue, 30 May 2017 11:39:07 GMT

Geometry. to draw or delineate (one figure) within another figure so that the inner lies entirely within the boundary of the outer, touching it at as many points as possible:

to inscribe a circle in a square.

This method of defining inscribed as apposed to circumscribed has been used for many decades it is also how I was taught at primary, secondary and tafe, Also it is how insert manufacture's the world over have depicted the geometry of their indexable insert.

Re: POLYGONS

Anonymous — Tue, 30 May 2017 12:12:10 GMT

Hi guys I had a closer look at the menu and noticed it is actually described correctly for the terminology used in the menu.

Inscribed polygon or circumscribed polygon, and not as I was expecting using the circle as the driving feature.

There for with an inscribed polygon the circle is to the outside and circumscribed polygon the circle is to the outside.

However I have always known from being taught at school is that the circle is the driving entity of any polygon as all geometry values can be determined from just 2 values being the diameter of the circle and the number of sides of the polygon, wether it be an inscribed or circumscribed circle.

I guess I have to learn another method but hey that wont take long.

Re: POLYGONS

cekuhnen — Tue, 30 May 2017 12:55:01 GMT

@Anonymous @jeff_strater @TheCADWhisperer @TrippyLighting

Maybe I am missing something here but

the polygon has two options to be created inside our outside a circle.

and that is also how the polygon creation process works by using a a circle as a reference.

You are not creating a circle here - thus I think that the tool names are correct!

Re: POLYGONS

Anonymous — Wed, 31 May 2017 11:23:45 GMT

Hi just my not understand of the menu as I have only been using fusion for about 20 hours in total so still getting to grips with different methods and ways of doing things. Now for those pesky polygon's how do I lock them to a given angle so that the primary edge can be set to the angle I want. I'm thinking I need to input a construction entity or something.

Re: POLYGONS

TheCADWhisperer — Wed, 31 May 2017 13:11:16 GMT

@Anonymous wrote:

....how do I lock them to a given angle so that the primary edge can be set to the angle I want. I'm thinking I need to input a construction entity or something.

Use a Horizontal or Vertical constraint on one of the edges as appropriate, or use a Construction line and and angle dimension to achieve your design intent.

Re: POLYGONS

Anonymous — Fri, 02 Jun 2017 22:31:04 GMT

Had feeling it was something like that. but can it be input directly in the polygon data just like how the circle diameter and number of sides is done, say from where 0 degrees is in the horizontal as the start point and then inputting the angle from the point without having to build or draw the constraint or construction line?

eg:-

Box data 1 = Circle diameter. - Eg: 50mm (inscribed circle)

Box data 2 = Number of sides. - Eg: 6 (sides)

Box data 3 = Angle about polygon centre (at polygon centre coordinates) from the horizontal

(with 0 degrees being at X+ from polygon centre for example when viewed in the X - Y plain)

and with midpoint of polygon side starting at 0 degree as base reference. (this die being parallel to the Y axis)

then setting this value to a given angle Eg: 45 degrees even -45 degrees

so data would be input as follows

50 enter 6 enter 45 or -45 enter

Personally I use inscribed circle as this is how cutting inserts, Hex bar and Square bar is referred to (also know as AF or across flats)

so this would be circumscribed polygon.

Cheers