Extrude sheet metal text with iLogic

[andrewiv]

I have an iLogic rule that creates some tags with numbers cut into them.  Most of the time it works great.  It takes a template, places some text on the face and extrudes the text.

Every once in a while I run into a problem when extruding the text.  What I want is to remove the interior from numbers like 0 and 8.  The problem is that every once in a while the flat pattern comes out like this.

[johnsonshiue]

Hi Andrew,

You did not attach the image or the part. Please do so. I guess the geometry was messed up. Let me propose a workflow and see if it would work better. Instead of removing the 0 or 8 profile from the text, keep them intact. Then use Delete Face -> Heal to remove the geometry created by the text. Could you try it and see if it works better? I am not 100% sure it can be automated easily though. Just an idea to share.

Many thanks!

[andrewiv]

Here's a part made in 2021 that shows what I'm trying to do.  The flat pattern is what I want to end up with.  I haven't tried my ilogic in 2021 yet.  Every once in a while the flat pattern looks like this.  It's almost like the face that is selected for flat pattern creation is changing to the inside of a 0.

[johnsonshiue]

Hi Andrew,

This is absolutely definitely undeniably a bug! Could you show me how to reproduce the behavior?

Many thanks!

[andrewiv]

I have attached a 2020 part that exhibits the behavior.  Open the part and look at the flat pattern, everything looks good.  Now edit Extrusion 9 and change it from join to cut.  It will give an error and if you accept the error and look at the flat pattern it now is the interior profile of one of the numbers.

On a side note, I had to create the extrusion with a join operation and then change it to a cut in order to accept it.  If you try to create the extrusion with a cut operation you do not have the option to accept the error.  But if you edit the extrusion you can accept it.

[johnsonshiue]

Hi Andrew,

Many thanks for sharing the file! I see the behavior. This has something to do with how flat pattern body is computed. When the drastic change happens in folded body geometry, the flat pattern body will also change and the downstream features fail to adjust accordingly (starting from the sketch coordinate system). I need to think about a better workflow to use here.

Thanks again!

[johnsonshiue]

Hi Andrew,

Let me ask you this. Is the flat pattern body purely for generating dxf file purpose? Do you create drawing views based on the flat pattern here? The reason why I am asking is that the flat pattern does not seem to be needed here. You can create the geometry in folded model with having to create the flat pattern. Is it true?

Many thanks!

[andrewiv]

The flat pattern is for exporting to a dxf and I'm pretty sure I need it because we want to have each of the tags as a separate entity and I don't want to show the interior faces of the numbers.  Creating a flat pattern is the only way that I've found to do this.

I have gotten past this by not including the flat pattern in the template and having the user select the face to create the flat pattern in my iLogic rule.  And then generating the features with my code.

[johnsonshiue]

Hi Andrew,

I am still looking into the failure. Did you try exporting the faces in folded body to DXF files?

Many thanks!

[andrewiv]

I hadn't tried that, but I want it to export as one file without the connecting ribs.  And I don't want to have to pick all the faces manually, sometimes there can be 100 or more tags in this file.  The flat pattern works really well for this since you can export the whole flat not just the individual faces.

[johnsonshiue]

Hi Andrew,

I took a look at the file closer. It seems that the flat pattern starting face changes, after you change from Join  to Cut in the Extrusion feature. It does not look like A-Side is defined.

I suspect with A-Side defintion, the starting face should be more stable. Could you try adding A-Side to the folded body? You will need to delete the flat pattern first.

Many thanks!

[andrewiv]

It still didn't work.  I deleted the flat pattern and defined the A-side then deleted the extrude feature that was there and created a new extrude cut using the same sketch.  When I activated the flat pattern it was a circle (interior face of one of the numbers.

[Anonymous]

First... as for why Inventor chooses the face that it chooses as side-A? I know that it almost always chooses the smallest face, but WHY? who knows... im sure they cant even explain it..

Second, in this case you are choosing (or having Inventor choose) the "A" side prior to making the extrusion/cut.. making a cut that separates a single face (Face0 is now buried & non-existent...and is now Face1-Face100) so a new Face has to be selected and  you're forcing Inventor to determine the new A-Side...  and as discussed, that's a risky business... the same reason you put all the connecting tabs in the folded-part, the flat-pattern will only bring up a single face and since there is no connecting tab in the 0, it has to discard all other faces... but obviously you already know that since you are removing the tabs in the flat pattern... I cant see your code, but I would make sure that when the user selects the face, it is prior to the extrusion... However if your intent is what I THINK it is, you want this to be modifiable and reusable.. In that case, when you create new faces, Side-A must be reassigned and back to square 1.

Third, you can also get there by changing the extrude to an emboss/engrave(not thru) but your flat pattern would have the inside faces. or maybe consider a stencil text.

Last, I assume this is being cut out on a laser, waterjet or some cnc operated machine and in most cases can utilize text layers as either etch or cut... if so, you can just add the text rule to the flat pattern and make sure text layers are on for exporting.

[andrewiv · Accepted solution]

I was able to make this work eventually by interrupting the code after the extrusion is made and having the user select the A side face before generating the flat pattern.

[bbeaudet0]

@andrewiv Would you be able to share the code for the rule that creates the text?

[andrewiv]

I can't share the entire code because it contains references to some internal files.  What are you trying to accomplish?  Maybe I can mock up a sample from my existing code.