'Use' and 'offset' in sketches

graham_lock

Hi,

What's the best way to place a sketch on a face and then trace the face edges into the sketch and then offset those sketch lines? The edges will be a combination of lines and curves.

Essentially the same as 'use' and 'offset' when using sketcher?

This seems a simple thing to want to do so probably missing something obvious.

Thank you.

S1mon

Take a look at this feature - it might be helpful:
https://onshape4frc.com/blog/using-lighten/
https://onshape4frc.com/blog/using-lighten/

Lighten custom feature
https://cad.onshape.com/documents/573f7d70e4b0fddafb52148c/v/85bb63ae5685ae3614116952/e/5eccf6d369b0312a728d77d3

S1mon

Offset curve (in the curve feature list - it's a 3D feature) is pretty powerful. It doesn't create the cleanest curves, and the extensions it creates are crap, but for ease of use, it wins.

glen_dewsbury

When using the offset tool in a sketch there is no need to 'use' then offset. It can be done in one step with the offset.

https://cad.onshape.com/documents/becbf8d99faea6d1f3a44ca6/w/a8497252213c5fe35717e0c3/e/ff4342b590ea2c2e4d790549

graham_lock

graham_lock

Thank you for your replies.

@S1mon I'm using:

var qEdges = qAdjacent(definition.face, AdjacencyType.EDGE, EntityType.EDGE);

    offsetCurveOnFace(context, id, 
    {
        "edges" : qEdges,
        "distance": 10 * millimeter,
        "offsetType": OffsetCurveType.GEODESIC,
        "gapFill": GapFill.LINEAR,
        "scope": OffsetCurveScope.OFFSET
    });

but it doesn't appear to do anything?
Can you point me in the right direction please?

@glen_dewsbury thank you but I'm trying to do this is Featurescript

S1mon

Sorry. I missed that you were trying to figure this out in FeatureScript. I haven't tried it there. I would recommend that you use the regular feature on an example first. It seems like opOffsetCurveOnFace is missing from the documentation. I would need to dig through the std source to see what it expects, but the user facing feature needs a direction and a surface.

graham_lock

I'm not sure how to use the regular feature tbh - how should the targets be assigned?

This is my test document:

https://cad.onshape.com/documents/2052a219ea2adad67082b149/w/33dc0c1b8d9e085f0038f32a/e/c2ffc53f3c65e0cb0739bcfd

S1mon

For a simple flat rectangle, you probably don't need/want opOffsetCurveOnFace. That will work, but its main purpose is offsetting edges/curves on complex curved surfaces.

What is your long term goal with this feature? What are you trying to solve that you can't do in sketcher?

graham_lock

In the real project the flat shapes will be fuselage formers or wing ribs for RC plane designs, each will potentially be a combination of straight and curved lines.

There will be many of each for each design and the intention is to automate offsetting the perimeters and then removing the inside of the curves for weight reduction.

I was hoping to generate the offset curves as sketches so I could draw other geometry within the curves giving the ability to remove selected areas..

Not difficult to do with sketcher and lofts but I'm just trying to automate as much of the grunt work as possible.

S1mon

Take a look at this feature - it might be helpful:
https://onshape4frc.com/blog/using-lighten/
https://onshape4frc.com/blog/using-lighten/

Lighten custom feature
https://cad.onshape.com/documents/573f7d70e4b0fddafb52148c/v/85bb63ae5685ae3614116952/e/5eccf6d369b0312a728d77d3

graham_lock

Thank you I now have some options.