Stamp Design: Problems with create web extrusion of 2D cog sketch

[kristianr]

Hi,

I'm relatively new to the whole 3D design thing so I'm probably missing something really important that manages to screw up my design.

I've been banging my head against this for several hours and finally decided to seek help as I can't get it to work no matter what I try.

I already failed importing and using line art in DXF and SVG format because the lines are never really closed no matter what I do, so I decided to just replicate the design in Fusion 360 and be done with it. Didn't work out quite as planned, unfortunately.

Here's what I want to do:

I want to create a 2D sketch, similar to line art, and then extrude those lines upwards (with a certain thickness and height) to create a stamp. Actually it'll be an impression tool for leather, but that's not really important.

The final design will be rather complicated, the Adeptus Mechanicus emblem. To demonstrate my problems I have only reproduced the cog and outer two circles.

My modus operandi:

From what I have seen I can either use the Sketch -> Offset function to create a thin face to extrude, or I can select the lines/curves and use the Create -> Web function to extrude thin walls.

First I created a simple solid box via Create -> Box. Next I selected the top face as my sketching plane and started my sketch.

The circles are simple center diameter circles. The centers are on the same spot.

For the cog wheel I I first created one of the teeth using the line tool, then used a circular pattern on the circles' center point to replicate it. I continued by making several center-point arcs (center is the circles' center) between the cog teeth, but did not close them yet. Finally, using the Coincident tool of the sketch menu I connected the teeth with the arcs to create the cogs.

Refer to the picture 1 '01_Cog_Sketch' for the design at this stage.

All faces are highlighting correctly, so the lines should all be closed and things be fine and dandy. Except they aren't.

Problem #1: Offset function doesn't work with the cog

Despite having closed my complete cog with the Coincident tool and the face highlighting working correctly, the Offset tool is complaining that the "Offset must be a simple (possibly closed) chain of curves". Refer to picture 2 '02_Cog_OffsetSelection_And_Error'.

I have no idea why it doesn't work. Visual inspection up to maximum magnification does not show any line breaks between the cog teeth and arcs.

Problem #2: Create -> Web function is working unexpectedly up to completely going bananas

So the offset version doesn't work. Fine. Selecting all those faces in the completes design would've been really laborous anyway, so let's try the Create -> Web function.

To make things clear, using both Create -> Web and Sketch -> Offset on the circles works. Only the cog is making problems.

So I select all the lines and points belonging to the cog, go to Create -> Web, go for symmetric mode with a certain depth and *essentially* it works. kind of. The problem is that at the vertices where the teeth and arcs meet, there's an indentation which shouldn't be there. Changing the thickness doesn't help. Refer to the upper part of picture 3 '03_Cog_WebSymmetric_And_OneDirection' to see what I mean. Not really what I want to happen at all. Not what I'd have expected either.

Okay, that didn't work either. But maybe, just maybe, that's only because I chose the symmetric thickness. If it's applying the thickness in one direction, maybe it'll work? Hint: It doesn't. Not only it doesn't, Fusion 360 goes bonkers. See bottom part of picture 3 '03_Cog_WebSymmetric_And_OneDirection' for the really unexpected result. Again, only the cog was selected. If fact, I only changed the drop-down from symmetric to one direction.

The result:

One thoroughly confused beginning user of Fusion 360.

I'll happily supply you with the file and any information you're going to need or try different design methods if they'll get me to my goal.

Any and all help is really appreciated.

Addendum: What I'd love to be able to do:

If there's some functionality to load a black-and-white picture, select and extrude the black parts of it and I've missed that I'd be really, really glad if someone pointed that out to me. Most likely wishful thinking, but no harm in asking, right? It'd save me a whole bunch of time.

[TrippyLighting]

Could you share your design ?

[kristianr]

Sure, I have attached it as a f3d archive.

If you need the file in any other format, just tell me and I'll try to get it done.

[TrippyLighting]

Thanks! No there is no way to simplt extrude a black and white picture. BTW if you have one of your object of desire it'd probably make some sense to attach as well.

What you are experiencing with the inability to select the whole cog profile seems to be a bug or at least a deficiency with the current implementation of the offset tool.

To save you the many typed words, you could create a screencast with the free screencast tool erom Autodesk, which integrates nicely with Fusion 360.

[kristianr]

Hi,

You mean my sketching reference? I don't mind, it's attached as well. I drew that up in Photoshop a couple years ago and as I'm getting into leatherworking and have access to a 3D printer I thought it'd be nice to make a couple of stamps for embossing the leather. Like I said, the design is fairly complicated and creating and importing paths as SVG/DXF isn't worth the effort as they aren't closed or being recognised as closed either. I spent the last 6-7 hours working on this, going from the most complicated to the technically easiest (but labor-intensive) approach with each and every iteration failing despite simplifying the problem.

Automatic recognition and extrusion of planes on pictures would've been too good to be true anyway. As I have some roots in programming I am well aware that this is not an easy problem and that Autodesks priorities are elsewhere. Again, I'm prefectly fine with doing it by hand, but that isn't working out well.

As far as the screencast goes, I'm currently on my somewhat underpowered laptop and Fusion 360 was a bit instable while I was working on that project. Before I simplified the process (i.e. didn't load an SVG/DXF with the paths or so) it crashed or froze about a dozen times times. Don't blame Fusion though, those files were huge resolution-wise. In any case, I don't think the screencast would've worked / been worth the effort in this case. Especially as I don't have that software installed.

It might be the offset tool, but my hunch is that the Coincident tool is not working perfectly, in that is it's not combining the curves and lines properly. In a previous iteration of the project when I was still using DXF files with paths despite the Coincident tool showing me that the lines are apparently coincident (the little symbol appeared next to the node touching a line), zooming in showed that they weren't even close to touching.

Then again, why the Web tool is going this bonkers when choosing a one direction thickness is absolutely beyond me.

Those might be completely unrelated problems.

For now I'd be happy if you could confirm this odd behaviour in your Fusion 360, and maybe could reproduce it by creating a similar cog in a fresh file.

I mean, I think the way I did it should be correct and work as intended, I don't think I overlooked anything.

[TrippyLighting]

It's not a problem for me to get a closed cog sketch profile  so that part, as expected, works fine. It's the offset tool that has a problem creating the proper offset.

[kristianr]

Interesting.

What about the odd behaviour of Create -> Web? Can that be reproduced?

[TrippyLighting]

I have not tried to reproduce that. I don;t think that you would ant to use that tool in this case anyway. You should just simply extrude the cog.

[kristianr]

If it were just the cog, sure.

Do take a look at the sketch attached a couple posts above and you will see that the complete design is quite a bit more complicated ('AdeptusMechanicusPNG.png').

Creating offsets for each and every feature will be a bit time-consuming, as will selecting the correct planes to extrude. Using the Web tool is significantly faster and more comfortable for my application. I need 1-3mm wide, and 5-10mm high 'walls' at the positions of those lines to emboss leather. See the upper part of the third image of the first post to see what I mean.

Though if the Offset tool will work and the Web tool won't, I'll do it that way.

Regardless of which way I'll have to go, I'd like to see if that behaviour is systematic or not because if it is I'll file a bug report. Especially the one direction version simply can not be the intended behaviour.

But for now I'll sign off for tonight. It's 2am and I am a bit tired.

I do thank you for all your time and effort. Depending on your time zone I also wish you a good night's rest, at the very least in advance.

[kristianr]

I have found out that the odd behaviour of the Create -> Web function seen in the bottom part of picture 3 ('03_Cog_WebSymmetric_And_OneDirection.png') is in fact correct and working as intended. By not unchecking the 'Extend curves' option my lines are being extended and display this weird pattern. So it was a user error.

That still does not explain why there is an indentation at the edges where the cog teeth meet the arcs though (see top part of same picture).

To recapitulate the open problems:

1) Sketch -> Offset tool is not working properly with the cog design

2) Create -> Web tool, symmetric, set depth, extend curves checked and unchecked produces unintended indentations at the points where the cog teeth meet the connecting arcs

I'll continue working on the design and see if there will be more problems. Progress and observations will be posted here.