Sketch offset problem

[tomjulier]

Apologies if this is a user error but I've seen reports of problems with sketch offsets so thought I'd share my experience here.

I created the design by importing an SVG of the Apple logo (https://commons.wikimedia.org/wiki/File:Apple_logo_black.svg), and extruding it; no problems there so presumably the contours were closed.

Next I created the rectangular panel and made a cutout by projecting the logo geometry and offsetting the curves by a dimension controlled by a parameter (I was aiming for a value of around 0.3mm).

Hopefully the screenshots show what happens with different offsets; with a value > 1.2mm both parts of the logo can be offset and cut out of the panel; 1.2mm seems to break both offsets; and less than 1.2mm works only for the main body of the logo.

I have attached the f3d file.

[TrippyLighting]

The trouble area is the concave area on top of the apple.

Past 1.2 mm of offset this radius gets too small. If you edit the curve in he original, imported sketch you can make the offset bigger.

You can window select the entire all logo and un-fix the entire curve. Then you can pick the curve and drag it up. Hold the control ket while dragging to temporarily disable snapping.

Or perhaps try to trace the imported curve in another sketch with a Fusion 360 spline, which will provide you with much finer control over the shape of the curve as the imported SVG papers to create one continuous curve.

[PhilProcarioJr]

@tomjulier

@TrippyLighting

The funny thing here is if your using parameters to control the offset it fails but if you do an offset and just set the value I can go a little over 10mm without any problems.

For me when I want to offset a shape like this I offset the trouble areas by themselves and trim where needed, but I understand the desire to do a single offset driven by a parameter.

To be fair even Solidworks fails in cases like this.

But if you do it manually and trim where needed you can at least finish the model.

[PhilProcarioJr]

@tomjulier

I would also like to point out it's bad practice to offset projected geometry...not saying you can't but you will run into all kinds of issues.

If you go back to your original sketch the offsets work very well....

Here is the logo with a 0.3mm offset in both directions.

[tomjulier]

How do you work out parts of the chain are causing the problem?

@PhilProcarioJr 

Looking specifically at the stalk, doing the offsets in the original sketch still fails with certain values e.g. expanding 0.3mm.

[PhilProcarioJr]

@tomjulier

Can you make a screen cast showing how it fails?

[PhilProcarioJr]

@tomjulier

See how your imported svg outline is green? That means it is locked. If you select the entire outline and unfix it from the sketch menu you can move stuff around.

What I usually do to find the problem is unlock the whole thing move stuff around to see the problem, then undo the mess and only unlock the problem spot and fix it.

I will make a screencast as I think I found the problem.

[PhilProcarioJr · Accepted solution]

@tomjulier

The problem is two points are ontop of each other with a spine connecting them.

[tomjulier]

Ah... I see the problem; I shouldn't have trusted the imported geometry. At least I've learnt how to check that now.

Thank you both for the help.

[levihouston]

I know this is old but this fixed my problem on a SVG I imported. Thank you so much!