Fillet problems

[BillGEGHV]

Hey All, I'm finishing up a model and have 3 fillet chains I can not get the radius I need, so im looking for some input and tips, and tricks. I need a .0625 on these, but can only get .03-.055. See the edge that is the problem in my screenshots.  What are the common reasons this type of issue comes up?  I have tried multiple ways to get these fillets done, including all together, individual chain, pick order, and 

The videos Ive watched are pretty basic, and I have not seen any yet that go over more complex filet issues. So if you have a video in addition to input, please post. 

[TrippyLighting]

Can you share the model?

[johnsonshiue]

Hi! Without seeing the model, I can only speculate. Either there are imperfect geometry conditions (near tangency, tolerance edges or bad geometry). Or it can be solved by adding the fillets in a different sequence. Generally, you want to start from the larger radius fillets first (not always). Then add smaller radius fillets.

Please share the model so that the forum experts can help take a look.

Many thanks!

[BillGEGHV]

At this point, Im not thrilled with posting the model since it's almost done, but here it is. I know it's hard to evaluate issues without the model.

Use Password 3658 for the download.  

Per JohnsonShiue, input I always approach fillets from biggest to smallest. 

In addition to my post yesterday, I now have issues with all the bottom edges on the buffer tube, as seen in these new screenshots. I can't get any consistency with this geometry.  My target radius for all these bottom fillets is between .0312-.0625, not sure what we're going with yet.  Please note that all the bodies making up the buffer tube area were created separately and boolened together before fillets, as shown in screenshots with bodies in colors.  

[BillGEGHV]

Here is the last screenshot

[johnsonshiue]

Hi Bill,

Many thanks for sharing the model! I took a quick look at the area of concern. I noticed that there were some unfavorable faces and edges. It is probably due to under-constrained sketch or imprecise modeling practice. I had to use Delete Face to clean them up. After that, I am able to add fillets successfully. Please take a look at the attached f3d.

Thanks again!

[BillGEGHV]

John, thank you for your help.  Ive looked the model over and see you have gotten the buffer tube area (upper left area with threads) to fillet. However, Im still unable to adjust fillet sizes on this area as well as the other area (mag release guard/fencing) in these screenshots, I made a 2nd copy of this file, deleted all the red errors to see if that's what I needed to do to increase the fillet sizes on these, but still not able to.  Im seeing the same bad (RED) edges in these chains.  

I would really LOVE to get more info on the troubleshooting steps you needed to take to fix these types of issues, and what you actually did, if you can elaborate.  I need to get past these things in my Fusion Modeling. When drawing, I "thought" I was nailing them all, but I guess not.   DO under-defined (projected edges AND construction lines and elements such as points) count as under-constrained sketch elements?  In other words, what Im asking is DO I need to also define all my construction elements? Any additional input would be very helpful.  HOW are you using Delete Face?? It does not work for me wherever there is a bad fillet but if the fillet is good, I can delete it. 

Thanks, 

  

[TheCADWhisperer]

@BillGEGHV 

I didn't dig into the geometry, but just a couple of observations.

1. I don't think this is relevant in this case, but I'll mention a tip that often it is best to leave some finish machining to after all fillets placed on the MMC casting.  This means additional material on the part that is cut from the part in modeling - just like the shop floor process floor - after the casting. So normally we recommend fillets at or near the end if possible, but casting fillets may need to occur before (virtual) finish machining faces.

2. If you don't want to post something publicly, in my experience @johnsonshiue is very accommodating to examining the geometry privately.

3. Once your issue is resolved I recommend that you go back and edit to remove any links and click Report to request the moderator remove any attachments (if desired).

[johnsonshiue]

Hi Bill,

There are a few places with conditions that are hostile to filleting. You may want to take a look at the f3d file I shared in prior reply. Look at Plane22, Boundary Fill1, and Delete Face13. These are the features I created to remove those hostile conditions. I think there are other places like this. You may want to clean them up before proceeding with more filleting.

I have to admit there isn't a magic button or magic workflow here. Even after cleaning up the geometry, I still need to try a few sequences and radius values to get the desirable result. It is an art and a science.

Many thanks!

[BillGEGHV · Accepted solution]

I was able to finally work out all the fillets on the buffer tube & reinforcement area, deleting a few faces that were causing issues.