Create dimension tangent to 2 circular lines?

johnny_1

Hello,

I cannot find a way to put a dimension on the drawing which is tangent to 1 or 2 circular shapes. See screenshot what I want to achieve.

What is the method to achieve this?

Johnny 

Pahl

Hi @johnny_1

As shown in my attachment the radius of the two circles plus the vertical distance between the two centers of the circles already equals the total hight dimension you are trying to create. If you want to add that dimension just for visual reference then I would suggest creating two construction lines and making them tangent to the circles as shown in my attachment and then add your dimension. Hope that helps. 

Pahl

Here is a link with some additional information on the sketch tool Dimension.
https://cad.onshape.com/help/Content/sketch-tools-dimension.htm

Be sure to check out "Driven dimensions" at the bottom of the page to learn about the difference between Driven and Driving dimensions.
Driving dimensions appear black and can be edited.

brucebartlett

You will find this limitation in drawings.  Hopefully, we will see an improvement so this kind of geometry can be easily dimensioned. 

As a workaround you can split the face or add a small bit of geometry in the part studio, at the place you wish to dimension from, this will then enable you to select a node with the 2 point linear dimension tool in the drawings. 

Pahl

Seems the topic was about drawings and I was thinking he was talking about dimensioning a sketch. My mistake, sorry about that.

NeilCooke

@johnny_1 - how you dimension this type of geometry changed back in September (I think) - dimension to the center point of each arc first, then drag the dimension extension lines to the extremities of each arc to get the tangent dimension you need.

brucebartlett

Thanks @NeilCooke, that works perfectly, but maybe not intuitively. 

Forget my workaround above.

johnny_1

brucebartlett said:

Thanks @NeilCooke, that works perfectly, but maybe not intuitively. 

Forget my workaround above.

Indeed I got the desired results. Definitely not intuitive.