Can't select a previously sketched face

[powell.richard]

Hi everyone.

I'm still new to Fusion 360 and I found a workflow problem.  

I create a sketch on the face of an imported .stp file I have.  My sketched area is placed on the flat face of the object but I run into a problem soon after...  Here is what is happening.

I want to draw my own 2 dimensional area on the flat face of an imported .stp file. I easily can sketch out my area. I then extrude it up .5mm . No problems at all so far. I then fillet the edges to make them round.  First I fillet the corners of the extruded face. I then do one more fillet  on the very top edge of the raised area.

I am so far still able to collect the face of this sketched area I made.  But after I extrude it back down .5mm (I want to just be left with a bordered area), I can't select the inner face of my sketch.  Fusion 360 is ignoring my existing borders/edges that are left.    Even if I try extruding it down only a little bit.   I guess I have to create an inner face first?   Shouldn't the raised/filleted borders that are still left create an inner face for me?

My imported .stp file is blue instead of light grey like I see online.  Does this mean the file has it's faces reversed or something?  

Thanks,

rick

[jeff_strater]

Can you share some more information, please?  Share the model you have so far, and some screen images or video showing the issue.  Thanks!

[powell.richard]

Hello,

I practice with Fusion 360 by importing random .stp files so this is one of them.

Thank you for checking/asking.  I made a 5 or 6 minute video to show the error (probably my error I assume?).  I run into the problem around 5:10 or 5:15 but if you watch the whole video you can see the .stp file being imported (which turns dark blue instead of light grey?)  But I'm able to properly sketch on surfaces until I extrude my sketch.   You will see what I mean.  At the end of the video, I can't select the inner surface that I created from the left over borders I drew.   Thank you for letting me know what I did wrong or how I can work around this. (I want to be able to select the inner surface at end of video).     Video has no audio.

[jeff_strater]

a few comments:

1. blue color.  STP supports color attributes, so most likely this color is defined inside of the STP file itself
2. the problem around selecting faces for extrude.  This is because at this point in your video, you create a New Body, with a depth of 50mm:
   
   Did you mean to join this shape to the main body?  Then, later, when you cut away the inside face, the depth is also set to 50mm, but because this is a separate body, it just removes all that inner volume:
   
   
   If you were to isolate that silver body, you would just see the the thin silver ring.  There is no surface at the bottom, you have removed it.  So, selecting the face for further extrude just goes to the main (blue) body face.

If you share your design here, I can illustrate on that model.

[jeff_strater]

here is a very simplified version of your workflow that hopefully illustrates:

[powell.richard]

Thank you for the information. I really appreciate you and this is helping me learn.  (I'm just practicing with this file as a prop by the way and is not to be made real). 

I'll share the file here and can you please show me how to do it correctly?  My extrude was no 50mm. The video is not high def. but standard definition and you couldn't see the .5mm.  I also tried many times to extrude less and still had the same problem.  I agree that you are perhaps right that I should not have chosen "new body" but should chose "join".  But I promise you I tried that option last night and I still could not select the inner surface after extruding.   What I'm trying to do is to add a .SVG geometric pattern to my inner surface and raise that back up .5mm.  That is why I first extrude up .5mm to make the border of my sketch.  Then I extrude down .5mm to have just the filleted borders left. Then, I need to be able to select the inner surface so I can add the .SVG geometric pattern as a design test/practice.

I have attached the .stp file.  If you could please show me how to correctly do it, I will forever be in your debt!

[powell.richard]

Thank you.  I just read that if you work with imported files, you should not use Timeline Mode but use Direct Modeling mode or you may have problems.  Is this my problem?   I'm beginning to wonder now after trying several more times, that when I try to use my .stp file to perform this easy operation, Fusion 360 is deselecting the actual Face I want to sketch on.   When I select the face I want to draw my initial sketch on, the selection disappears (the whole object becomes same color).  So I think my sketches are not truly on the surface of the body according to Fusion 360.   Can you try my stp file and try to see what I mean please?  Do I have to "break" that chain link thing to truly edit on the file?  There is a chain link and an option to break it.  Is this why I can't draw on it?

[jeff_strater]

sorry, you are right.  It is .5 mm, not 50mm.  But my point is the same.  If you extrude by .5mm and then cut away by the same amount, the result is as in my simple example.  There is no face there to select - it is just the outer ring.

If you could share your F3D file here (not the step file), I can show you on that, but I'm certain that this is the problem.  Either you should use Join in that first extrude, or reduce the cut by some amount so that it does not penetrate all the way through that second body.

[powell.richard]

Thank you. I'm attaching the F3z file.  I have tried only extruding back down by .2 and I still can't select inner surface. But my gut tells me that because this is an imported file and I am working in Timeline Mode as opposed to Direct Modeling Mode, that is the source of my problem. I just read that only in Direct Modeling Mode can you manipulate the individual surfaces of imported .STP files.  Correct?

I just read this and haven't had a chance to test this out (change to Direct Modeling Mode).

I am having problems importing this correctly so I would really appreciate if you try it and let me know please?

Thank you.

[jeff_strater]

Thanks.  But, this design does not contain your sketches, extrudes, fillets, etc.  I would like to see the design that is shown in your video, with that sketch and extrude information.

This has nothing to do with Direct Modeling vs Parametric.  You will have the same issue in Direct Modeling.  It is just simply that you have removed all the material from that body, so there is no face to select, and that is why you cannot select it.

Here is a version of my simple case showing that, if you use Join instead of New Body on the original, then there will be a resulting face there that can be selected.

[powell.richard]

Thank you. I've attached the file you want below please.  I tried on this one to "Join" on original and I still can't select the inner surface after I extrude back down. I believe that Fusion 360 is not allowing me to sketch on the actual surface in the beginning. So at the end, Fusion 360 doesn't think my sketch was ever on that specific surface that I'm trying to draw on. It will let me select the surface before I begin sketch.  But not sure if I'm truly sketching on that surface I want because the whole body turns the same color as soon as I select the Sketching tool.

Can you see if you can actually sketch on the true surface I want at the beginning? I believe that is the problem.

[jeff_strater]

one more insight.  One reason why the extrude does not join to the body is because you have not activated the component that owns it.  You will need to do this edit in the design or component that owns the body.

[powell.richard]

Ah, so I'm not truly able to edit this body yet.   I had a feeling something major like that was wrong. So this is why my sketch is not truly on the body.    

How do I unlock it correctly?   My component is already activated I thought because of the circle with the dot in it.  I assume I have to have the dot in the circle for the very top item on the list.    I guess I'll try that unless there is anything else I did wrong.  Thanks for your help!

[jeff_strater]

yes, that is the issue.  Because your top-level design refers to an external component (FMDA DD17.2 V1.4 Frame), you cannot join to that body from that top level.  You have to open that design directly, and do your work there.  Then, Join will be enabled, and you will not have this problem.

[powell.richard]

Thank you. I have been mostly successful now.  I was before doing a weird thing I guess where I import the object from Data Panel but then create new component and if I have both, I can't perform operations even with top object activated. But I can sketch on the surface better now by only importing from Data Panel and just activated main object.

But, I get an error when I extrude back down .5mm.  I get "error with geometry....be sure there is a clear overlap".   Is this simply because of my fillet parameters and trying different fillet parameters should fix that?

thanks,

rick

[jeff_strater]

most likely, yes.  I suspect it has something to do with the fillet radii used on the top face.  If I recall, you used 2mm, perhaps some other value will work.  What is your next step in this process?  Once you have cut out this face, and can select it, what do you plan to do next?  I'm essentially asking whether this cut needs to be exactly 0.5mm, or if some other value can work here.

[powell.richard]

I'm so close thanks to you. You have essentially solved the big problem. I am able to both edit the surface of this object and I better understand the fillet process. (I don't get that geometry error now).

The only weird this left is that even if I create "Join" option when I first extrude my initial sketch on the surface up .5mm. And then after I properly make fillets for the edges (I don't get the error anymore), if I extrude back down .5mm, I still can't select the inner surface.  I can only extrude down less than .5mm to be able to pick the inner surface.  In a tutorial I found online with the same exact file, the other person is able to extrude back down .5mm and still pick the inner surface.  Everything I'm doing is the same. My solution now will be to just extrude it back down .45mm which is working fine.

Would you know why this is happening as my final and last question?  Thanks for all the help today. You have been great.

[jeff_strater · Accepted solution]

Sorry for the slow response - day job got in the way...  I definitely saw this myself, and I don't know what causes it.  However, when I tried to reproduce it just now, it worked for me.  Model is attached.  Again, I have no idea why....

[powell.richard]

No worries.  I just simply extrude down -.49mm and the face remains correct for me to select. AND when I download your file that you said allowed you to do it all the way down and select, you were right!  So I just saved your file and will use that.

I talked to the original guy who did the tutorial and he questioned why my file opens blue but his opens grey.  So I wonder if I have a slightly different file from him.

Thanks, you did help me today though!

[jeff_strater · Accepted solution]

yes, probably so.  In case you are interested, yes, the blue appearance is in the STEP file.  If you want to get rid of it, just open the Appearance dialog, select the material, right click, and choose Unassign and Delete: