How To Dimension An Ellipse In An Inventor .IDW

[sdreed52]

Our company, which sells office furniture, wants to offer an elliptical shape table. My project is to model and draw the table top. The modeling part is easy. I  just used the elliptical tool to create the sketch then extruded it to create the 3D shape.

Next I started a new drawing, placed a top view and began to annotate it and there is my problem. The general dimension tool will not select anything other than the outside shape. I need at a minimum the radius of the major & minor axis. See screenshot below.

Another post suggested use Retrieve sketch dimension, however in my Inventor (2021) I can't seem to find that option. For example, in the Edit View, under Display Options, there is no such command. Under the Recovery Options tab, there is an All Model Dimensions command that is grayed out.

So, I am at a loss as how to dimension a simple thing as an ellipse. I've spent quite some time searching this forum but haven't found anything to help so my last resort is to post here. Surely someone has needed to make a drawing of some ellipse shaped object and run into the same issue.

Thanks for your help,

Steve

[LT.Rusty]

This (or overall length / width) is usually all that I find is necessary in terms of paper documentation. If it's for manufacturing purposes, I'd much rather have someone pull the shape directly from the model than try to approximate it based on numbers on paper which are already approximations and... anyway, it can get messy.

[Gabriel_Watson]

Right-click your ribbon to make sure this tool is visible:

Above is for 2024, but should be similar in 2021:

https://help.autodesk.com/view/INVNTOR/2021/ENU/?guid=GUID-675E2605-5E63-40C6-9DCB-E2862CCB3D71

Alternatively, right-click the drawing view:

https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/Retrieve-Model-Ann...

I just use the out-of-the-box dimension tool and it works fine for defining the ellipse:

[CCarreiras]

Hi!

Fist, just create the view, (click ok in the image you posted).

Then go to annotate  tab and select "dimension" to start creating dimensions:
Select the geometry, you will find several green dots to attach the dimensions.
Tips:

you can create a center mark to help you attach the dimensions. Check the image below.

You can use retrieve dimensions, it's on the annotate tab, orange circle in the image

[Frederick_Law]

A fully dimensioned ellipse:

There is no "radius" in ellipse.

https://en.wikipedia.org/wiki/Ellipse

[karthur1]

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@sdreed52 wrote:

....... I need at a minimum the radius of the major & minor axis. See screenshot below.

Thanks for your help,

Steve

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The radius at the major and minor axis is just half of the overall dimension. I can show you mathematically, but just think of it as a "squashed" circle of radius R.  You should be able to dim from the center to the edge by first putting in some centerlines.

Kirk

[LT.Rusty · Accepted solution]

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You should be able to dim from the center to the edge buy first putting in some centerlines.

No need even for the centerlines- just start the dimension tool and click the ellipse, you'll start pulling a dimension whichever direction you move the mouse. 

[sdreed52]

Thanks, but the problem is my Inventor will not create dimensions of any kind.

Steve

[sdreed52]

Thanks but I fully understand the geometry. I need to create dimensions on a drawing view and my Inventor (2021) will not do that.

Steve

[sdreed52]

Yes, that does work on a normal 3D created ellipse. I hadn't noticed the green dots before so thanks for the tip. My model was created (by someone else) using iLogic. This model seems to be different for some unknow reason. It isn't a spline or polyline but still behaves differently than an identical model I created myself.

Thanks for your input,

Steve

[sdreed52]

Yes, that should work but doesn't in this case. The original model was created (by someone else) using iLogic and it will not dimension like you indicate. I recreated an identical model and it will dimensions as you show. Their model should work, it is just a standard sketch and extrude driven by the iLogic rules but for some reason doesn't.

Thanks,

Steve

[Mario.VanWiechen]

I could be wrong here, have been many times but an ellipse is the face of a round part cut at an angle. They are a pain because the outside is a polyline or a spline. 

Model the tabletop as 2 different tangent radius's, it will be easier to manufacture and measure

[sdreed52]

I agree. Now to just get to that point. As someone else suggested, I added centerlines and points. That works but seems like a workaround. I am an old SolidWorks user and I don't recall this issue with it.

Thanks for your input,

Steve

[sdreed52]

Sorry, I just realized it was you that suggested adding centerlines.

Thanks again,

Steve

[Frederick_Law]

Attach your file.

I just use the ellipse tool to sketch.  No iLogic required.

[LT.Rusty]

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@sdreed52 wrote:

Yes, that should work but doesn't in this case. The original model was created (by someone else) using iLogic and it will not dimension like you indicate. I recreated an identical model and it will dimensions as you show. Their model should work, it is just a standard sketch and extrude driven by the iLogic rules but for some reason doesn't.

Thanks,

Steve

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It sounds to me like this is not a normal ellipse, then. I'd really like to take a look at the part.

[karthur1]

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@Frederick_Law wrote:

...

......

There is no "radius" in ellipse.

https://en.wikipedia.org/wiki/Ellipse

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Well there can be. You just have to convert it to cartesian coords.  Here is an equation that can be solved for "r" at any angle of the ellipse.

Kirk

Ellipse Equation : 

Convert to cartesian coordinates to find x,y on the curve.

 

Which becomes:

[Frederick_Law]

Oh yea, a point radius.

An arc with 0 length.

Infinite number of radius, angle and points to define the shape.

[sdreed52]

Yes, I was in error when I said "radius". What I should have said was major & minor axis. Unfortunately, I can't get those dimensions on the drawing view either.

Thanks,

Steve

[CCarreiras]

@sdreed52 , Can you post here your drawing, or an example?

So many threads to add dimensions to a simple ellipse??!!!!
Is even an ellipse?? I guess not...