Same exact design and dimensions for two different documents. One document won't make the chamfer...

[Frederik.Andersen1]

Hey everyone 😄

I think I've somehow managed to break a document... First some backstory.

I'm currently designing a battery that will be enclosed in an enclosure. The enclosure consists of a lid and a casing. The lid need to have a small extrusion all around the inside of the casing and I want to add a chamfer to that extrusion.

When I first made the chamfer (2mm, same height as the extrusion), it all worked perfectly fine. However after changing some parameters back and forth, and even ending up with the same parameters as in the beginning, it suddenly stopped working. I could only make the chamfer like 1.9999mm instead of 2mm...

Luckily I made quite a lot of saves along the way, so I went back to find one where it was working and started comparing measurements. I noticed there somehow had appeared a very small difference of 0.001mm in a few places, which I assumed made it unable to work. Me thinking, "okay, I'll just make all the dimensions EXACTLY the same for both documents and it will be good". Many hours of furstation and sleep goes by and it's finally the same. Well guess what, it's still giving me the same stupid issue... I've even remade the sketches for BOTH documents a few time by now and still the same one is working and the other is not.

So here I am. At this point it's honestly not even about just finishing the battery ASAP, I just really want to find out why the hell it's messing with me.

I've checked all dimensions many times by now and they are exactly the same in both documents. Or, I assume they are. Maybe the difference is too small for Fusion to tell me.

Here are links for both documents.

The Battery V4: https://a360.co/3war584

The Battery V5: https://a360.co/3w7Xyfc

"The Battery V5" is the working document, while the "V4" is not working.

I'm sorry for my bit messy timeline, however I'll just try to help explain what's going on.

The lid is being created in the group named "Basic lid", which I assume is where the issue is (A bit earlier in the V4 document though). The projection for the small extrusion made on the lid, is made back in "Lid mounting in case". The projection to make that, is made even earlier in the "Mounting holes in PCB".

There are quite a lot of yellow/red markings, however they appear after the lid has been made, so I don't think it matters.

I hope it helped clear up some things, however feel more than welcome to ask 🙂 While writing this, I also noticed it seems quite complicated, though not sure if that's just how it's supposed to be, haha 🙂

I'm still very new to fusion, so please let me know if any specific informations are useful 🙂

Really just any help will be gladly appreciated.

May you all continue on with a great day 🙂

[Frederik.Andersen1]

I just noticed something very weird. Apparently in the V4 document, the chamfer works on half of the extrusion. Hope this will help some 🙂

[Frederik.Andersen1]

I tried playing a bit more around with it and found something interesting.

By cutting the chamfer into 2 operations by first taking the long sides and afterwards taking the 2 short sides, it works completely fine.

I won't mark this as the solution though, since I still don't know why it's happening, but it's at least one step further 🙂

[jean.flower · Accepted solution]

For me, the alarm bell rings when you tried to make that chamfer and need to pick extra edges to coax the chamfer along what seems like a tangent sequence.  That's an indication that something is slightly misaligned at that vertex. 

Focussing on that vertex (or one just like it), if I make an extrude from your sketch 11 of these regions then a fillet won't run around where I drew the arrows - so the circular edges are not tangent to each other.  But if I edited sketch 11 as shown in the second image, the fillet works as expected.  This might be a clue along the way?  Hope it helps!

 

 

[Frederik.Andersen1]

Thank you so much! 😄 🙏 Now I can finally have a good night of sleep 😊

You were totally spot on. I was not able to figure out exactly how you made it work, but I changed things up a bit, which worked out in the end.

I believe it was basically impossible to make the case corner completely symmetrical by using the offset line from the PCB. The PCB and case fillet was never made to perfectly fit each other, just eyeballed, which I assume could explain why the difference was so small.

I ended up mostly ignoring the offset line from the PCB, only using a reference point as a guide. From there, I was able to create an arc that was completely tangent with the case edge and newly made circle. The "tradeoff" is now there is not a perfect .5mm gap all along the edge, but it's 0.006mm further away. Don't even think it qualifies to be called a tradeoff, haha 🙂

I hope what I said made somewhat sense 😅 at least what you told me did, haha 😅

Again, thank you so freaking much! Your help was greatly appreciated!

Biggest lesson I'll take with me from this, is that Fusion is WAY smarter than me. If Fusion doesn't do as I expect it to, it's most likely due to my own mess up.

Happy easter and stay safe! 😄