Basic principles of filletEdge trying to understand


I need to understand why filletEdge stops at end of edge (well almost, slight ‘flash to trim’) on inside yet goes way off on outside edge when I see no reason for that at all.
If it had caught the radiused curve of the arch it could have got confused but it misses it., carries on catching the next bit and carries on out into space, at the other end there isnt even an arch, a very simple area, yet away it goes.

What are the pre-requisites for having a FilletEdge that ends at end of object ?

I had boolean unioned the end plate to the side plate, then run MergeAllfaces.
Then did the inner fillt 0.05inch, and had to trim away where it bulged out a bit.
Then do the outside edge 0.086 and wonder why it did this ?

Also I had chosen trim yet the edge remains.

I have also used the trim command in Front view to trim off the excess but now have a double line, confusing to have curves and seeing double or triple etc. I know the representation of a surface s facets can differ from the true edge but does also the line denoting the true edge differ ? should the lines not be as one ?

do all CAD progs do this ‘into space’ fillet and double effect ?

why does fillet zoom off edges.3dm (125.5 KB)



This has been around a while but I think has the details you’re looking for:



Its just done it using FilletEdge trim yes on a really simple L bend, I have looked at those multi edged ones but cant relate the steps there to my simple L bend as it being simple I cant see potential failures and how to fix it.
Apologies if I have missed the one that showed this fault and the remedy, but the videos didnt show the fly outs and failure to trim and explain causes.
baffled, taking me many hours to do simple bends.
0.05" inner and 0.086" outer.
does it whichever order I do them in.
FilletEdge simple L bend fail.3dm (535.0 KB)
would all CAD progs do this on this example ?


it fails because it touches another edge, that’s why I always work with edges and isocurves checked in shaded view:

and for a quick solution you can make those Sweep 1 surfaces and the use CreateSolid

and then you can delete what’s left

in some cases could work to make a macro like:
but I didn’t test it

Hi Diego,
I had run mergeAllFaces prior to running fillet so why hadnt the foot become acceptable as it was Boolean Unioned then after MergeAllFaces that seam shouldnt have been there.


it wont merge those edges because one of the surfaces is not planar. MergeAllFaces only works on planar faces.

Hi Diego,
well thats somewhat limiting then.
I have started using MergeAllSurfaces as some kind of wonder drug to heal before filleting.
Is there not a command that would fuse together such surfaces and simplify the item, and avoid such fillet flyouts ?

I do wonder what would happen in other progs and what procedures they have, are all afflicted by such edges ?

So as there is no means of losing that joint I have to accept fillet flyout then trim it off ?


I guess you have to do what you can with what you have. instead of complaining and /or comparing with other packages. solving that issue took a few clicks, then the next object and so on.
MergeAllFaces always worked like that.
MergeSrf works on any kind of surface while they are untrimmed and similar in structure within the file tolerance.
In my opinion, a 3d program is like a language, you have to learn its own rules to communicate something. if you use your own rules, no one will understand you. I mean I rather learn how the program works on its ways instead of trying to make it work in my random individual way.

I shall think of MergeAllFaces as MergeAllPlanarFaces so as to be aware of what it does.
A lot of my surfaces are trimmed but MergeSrf is worth a try, If I run one then the other prior to filleting it cannot be a bad thing to do.
I was simply curious on how other progs tackled filleting. We have to work with what tools we have got though no harm in peeking outside the box incase future development can lessen problems that arise by seeing how others tackle it, though copyright might stop that.
If someone comes up with an advanced filleting plugin or advanced trimming plugin we install it if it appears useful, rather than say I will only use the default tools.