Trouble with Fillet Consistency

peter_wu189

I am looking for some help understanding what is going wrong with some fillets I'm working on.  The item is a dryer handle.  After a first print, it was concluded that the (4) posts that clip into place were to fragile at the base, so I wanted to go back and add some fillets at the base to (hopefully) strengthen them.  Of those (4) posts, the center (2) worked with the fillets without issue.  The ones on the outside seem to be inconsistent.  I've gotten some of it to work on one of the outer posts, but the mirror image on the other side won't replicate.  I'm confused on this, as it is the same as the other side, but not acting the same.  Any helpful information would be appreciated.

https://cad.onshape.com/documents/6a78bc4fb9163b99630f7723/w/00c48d76e9ad5bd796446b0f/e/28a8e5c1dc178191fd4573da

S1mon

There are a few things that are working against you:

1. The curves that you're sweeping to make the main shape are a little lumpy and not tangent to the flat wall. I would recommend using Bézier curves that are degree 2 or 3 for this simple of a shape.
2. Extrude 8 is set to a depth dimension which causes it to create a very tiny (0.05mm wide) piece of geometry. I changed this to an up-to-face depth and it got rid of this:

3. The order of the fillets makes a big difference. I was able to put all the fillets on the sides of the snaps (after fixing #2) and then on the fronts/backs.

See this document:
https://cad.onshape.com/documents/b74a64bd2f7e7b83dfa55c6e/w/4c2ac1cc9599a71ebe090360/e/00ded0320422ec48201d347d



Also, any time you are creating geometry by sketching the same thing a bunch of times or extruding and cutting away (see Extrude 4-6) I would question your approach. There are many people who would recommend modeling half of this whole part and then mirroring it. I'm not fully in that camp because I've worked on too many projects where I end up needing to make 1 of the 4 snaps different later, or one of the alignment hooks on the left different than the right later. However, there is a lot of duplication of work here.

Assuming that you want to turn this into a production part later using injection molding, there are more issues you will run into (draft, some thick wall conditions in the corners and at the roots of the snaps, and some DFM challenges with the shutoffs and parting lines at the corner hooks).

S1mon

There are a few things that are working against you:

1. The curves that you're sweeping to make the main shape are a little lumpy and not tangent to the flat wall. I would recommend using Bézier curves that are degree 2 or 3 for this simple of a shape.
2. Extrude 8 is set to a depth dimension which causes it to create a very tiny (0.05mm wide) piece of geometry. I changed this to an up-to-face depth and it got rid of this:

3. The order of the fillets makes a big difference. I was able to put all the fillets on the sides of the snaps (after fixing #2) and then on the fronts/backs.

See this document:
https://cad.onshape.com/documents/b74a64bd2f7e7b83dfa55c6e/w/4c2ac1cc9599a71ebe090360/e/00ded0320422ec48201d347d



Also, any time you are creating geometry by sketching the same thing a bunch of times or extruding and cutting away (see Extrude 4-6) I would question your approach. There are many people who would recommend modeling half of this whole part and then mirroring it. I'm not fully in that camp because I've worked on too many projects where I end up needing to make 1 of the 4 snaps different later, or one of the alignment hooks on the left different than the right later. However, there is a lot of duplication of work here.

Assuming that you want to turn this into a production part later using injection molding, there are more issues you will run into (draft, some thick wall conditions in the corners and at the roots of the snaps, and some DFM challenges with the shutoffs and parting lines at the corner hooks).

peter_wu189

S1mon, 

Thank you very much for your solve, as well as your constructive critique.  I know that my drafting has much to be desired.  I'm happy to have gotten as close as I did. 

Cheers to you.