topic Re: Why is the arc radius different to the dimension? in Fusion Design, Validate & Document Forum

Why is the arc radius different to the dimension?

lemelman — Sun, 02 Jan 2022 11:04:19 GMT

Part of my model consists of a rail made of bent tubing. I've created a 2D drawing and tried to give dimensions etc with reference to the centrelines of the tubing. The centreline tool works fine for the straight bits but doesn't work at all for the bent bits, so I've used the sketch tool to create centreline arcs that start and end orthogonally to the straight bits.

Linear dimensions to the 'proper' centrelines work fine, but the arc radii don't match the dimensions.

Why?

Why is the arc radius different to the dimension?

lemelman — Sun, 02 Jan 2022 12:26:54 GMT

I figured it out (well actually my son did) - the drawing was scaled 1:2 but the sketch isn't scaled at all. In fact, it doesn't seem possible to scale a sketch - which is rather surprising. How can I dimension the centreline of an arc? There is no tool to draw the centreline of an arc so the only alternative is the sketch facility, but I can't figure out how to scale a sketch. Any takers?

Re: Why is the arc radius different to the dimension?

laughingcreek — Sun, 02 Jan 2022 17:41:39 GMT

you can create a sketch of that center line in the design workspace, and then expose it in a drawing. I think it has to be a regular line, not a construction line, but it will display as a dashed line type in drawings.

Re: Why is the arc radius different to the dimension?

davebYYPCU — Sun, 02 Jan 2022 19:01:48 GMT

Sketch > Modify > Scale

Trick is not to select the anchor point as part of the selected articles to scale.

Far better to draw / edit full size in the first place, but can be done.

Might help....

Re: Why is the arc radius different to the dimension?

lemelman — Mon, 03 Jan 2022 12:17:25 GMT

Sorry, but I don't understand what you mean. What is an anchor point and
what is its purpose?

Re: Why is the arc radius different to the dimension?

davebYYPCU — Mon, 03 Jan 2022 12:22:31 GMT

The scale tool requires selected articles to change size,

relative to a selected point (anchor) as it will not be moving, this point, must not be part of the first selection.

Might help....

Re: Why is the arc radius different to the dimension?

TrippyLighting — Mon, 03 Jan 2022 12:46:14 GMT

I have not tried how this works in any of the other CAD packages I use.

My expectation would be that if the drawing environment offers the ability to create a center line, then I would expect when dimensioning it that the dimensioning takes the drawing scale into account.

I would NOT expect having to use a workaround.

Re: Why is the arc radius different to the dimension?

laughingcreek — Mon, 03 Jan 2022 15:20:33 GMT

after reading the other replies i'm wondering if I miss-understood your question. I'm assuming you drew the your "center lines" while in the drawings environment, using the rudimentary drawing tools there.

if not, disregard any of my replies.

if so-

-there isn't a scale setting for an entire drawing, each individual model view has it's own scale setting. lines draw in the drawings environment aren't associated with a model view, so don't have a particular "scale."

-the "center line type" in drawing views is just referring to how it looks (continuous, dashed, etc.), not it's function. still just a "dumb line"

-create a sketch in the design environment (in this pic I made a sketch and then used pipe command)

when you make your drawing, toggle the sketch on-

Re: Why is the arc radius different to the dimension?

lemelman — Mon, 03 Jan 2022 15:23:26 GMT

I just don't get it - could you demonstrate with a sketch on an actual 2D drawing.

Re: Why is the arc radius different to the dimension?

TrippyLighting — Mon, 03 Jan 2022 17:32:34 GMT

The 2nd screenshot in @laughingcreeks post is from an actual drawing.

Re: Why is the arc radius different to the dimension?

laughingcreek — Mon, 03 Jan 2022 19:01:09 GMT

maybe this is clearer-

Re: Why is the arc radius different to the dimension?

davebYYPCU — Mon, 03 Jan 2022 21:04:42 GMT

Nope, I do not ever comment on 2d drawing problems,

only Modelling, and on this occasion was responding to message 2 above - to scale a Sketch or some of its articles.

Might help....

Re: Why is the arc radius different to the dimension?

lemelman — Tue, 04 Jan 2022 09:57:36 GMT

Thank you, that was much clearer and solved the problem completely.

I didn't know you could include a design sketch into a drawing.