Fillet blend & patch issues
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 From:  Jeff (USD5000000)
4321.4 
Hello Michael, Burr,

Thanks as always for your suggestions and advice...

My comments...

1. The model has a lot of the pieces hidden. I guess I saved it with only the two pieces showing.

2. "In situations like that you may want to trim the surface to what you know are common curves (possibly edges) rather than trying to intersect the surfaces directly which is what the booleans will try to do."

"But try using the Trim command to cut the piece that is giving you the zig-zag result instead of using the boolean - if you have a curve you can trim your surface to rather than a grazing surface it can give you a better result."

>> I guess I'm a little confused with what I should do. I think I did what you suggested. I made a set of 3 lines that that I used to cut up both solids and then tried to UNION them together. The lines were snapped to edge of the swept surface.

I used a boolean difference to cut up the solid. Are you saying that I should use trim instead of DIFF when I slice up solid that I'm going to glue back to other pieces?

3. "A couple of things that I did notice about the one that you did post though is that you've got some planar areas that are diced up into some small plane fragments, like this here:"

>>This happened because I took the neck pocket shape and cut and extruded it to use it to "rout" out the neck pocket area. I'll clean it up if it causes issues.

4. "Then the other thing that I did notice about the model that you posted is that the ends of your fillet pieces here do not seem to have a very nice regular shape to them, there seems to be a small sudden swoop right near the end:"

>> I saw this too, but wasn't sure why I got this or how to fix it. I "borrowed" curves from the two filleted bodies and swept a curve between the two radii and along a curve I extracted from one of the bodies.

5. "For more advanced kinds of surface modeling like this kind of a project, where you're building some surfaces of your object individually, you tend to use Trim for that kind of a thing to work at the surface level as well - booleans are more focused on combining together solids and may have difficulty in situations where you're better of trimming with a curve rather than doing surface/surface intersections."

>> Is this referring to #2 where I should use the "trim" command instead of Boolean DIFF?

I'm using a lot of time trying to figure the best way to model things, but I do appreciate everyone's guidance. I think I'm saving a lot of time overall.

I was going to try another approach to the whole fillet blend situation. I was going to try and use those swept curves and "glue" them on some solids and then patch up the holes. I guess I should learn both methods since in some cases one would work better than another.

I'll study Burr's post before I comment on it.

Thanks guys.

Jeff
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 From:  Michael Gibson
4321.5 In reply to 4321.4 
Hi Jeff, well with my previous comments I was kind of confused about what you were referring to originally since I didn't see anything similar to your screenshots when I opened up your model file.

In those screenshots I just saw what looked like 2 fillet pieces kind of directly overlapping on top of each other in the same space - if one of those fillets was supposed to be cut by the other one in the final model, then instead of using boolean union to do that kind of cutting it could be better to trim the fillet pieces with a curve - I was presuming that you were trying to kind of splice together 2 models that had some overlapping surface area in them? That's what it looked like from your original screenshots anyway.

- Michael
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 From:  Michael Gibson
4321.6 In reply to 4321.1 
Hi Jeff, so I'm having some difficulty following along with your steps.

In your first post in this thread here, you posted this:




But even with showing all the hidden objects in the file you posted, I can't seem to find those objects - the closest things seem to be these?




Is it possible for you to post the model file that matches the screenshots that you posted? That would make it much more feasible for me to attempt to follow along with the steps that you are talking about in your question and to try and understand what you were doing.

When I can't get at the actual 3DM model file that goes along with your screenshots, it makes it much more difficult for me to understand, sorry.

So when I was talking about surface trimming, what I meant was something more along the lines of taking this long fillet surface here:



And trimming it by the edge of this smaller custom sweep piece that you made here:




Instead of doing a boolean to combine things together, you can also work with things at the surface level, trimming away parts of surfaces that you don't want to keep and then using the Edit > Join command to glue the surface pieces together back into a solid.

I guess you are doing something more like trimming each piece with a common line?

> Is this referring to #2 where I should use the "trim" command
> instead of Boolean DIFF?

It's more like - if you want to build a custom surface by a sweep for one piece of the model, to then splice this new surface into place you may want to use the Trim command to cut the original long fillet at the place where your custom piece starts so that will make an empty area for it to fill in.

That's a kind of surface modeling workflow where you can work with individual surfaces for a while instead of doing booleans. To do the surface modeling type workflow you generally use the Trim command to cut the surfaces up instead of booleans - booleans are more for operating on solids.


I am still pretty confused about your question though - I can't find the models to match your screenshots and I have not actually even seen where the zig-zag is located yet. So that's making it difficult for me to give you the best advice since I don't fully understand your construction method yet.

- Michael

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