Your issue is that in your original curve creation, there is a hard point located in the curve, that creates a seam edge in the extrusion, then your next cutting curve, is just "skimming" right along that seam edge at something like .001, which makes the tiny surface that kills the fillet.

So here if you run seperate on your original cutting curve, you will see this point here...(Thats why the rebuild makes it work, as you can remove this seam edge)



So if you extrude that middle surface before you cut the ends off, you will see this seam in the extrude (note the second cutter above)



Then when you slice with that second cutter, you create this little surface here, that kills the fillet.

So to use the rebuld command to clean up seams in surfaces like this, before you use thos top cutting curves, select them and hit the tab key then type Rebuild.. Select refit and delete original, with a tolerance of soemthing like .001.. Then when you extrude your surface, it will be clean and the next cutter will prodice a single cut that should then fillet ok...

BTW, in your original surface, there is a downward "dimple" in the center.. Maybe if you recreate this, you would want a tangent curvature? FYI

Thanks, BurrMan.

Well spotted – points and dimple. I will follow your findings. Also, thanks for the Rebuild explanation.

Good lesson there: use Show pts to check the curves *first*.

Leonard

Hi Leonard, just to clarify what Burr was saying, the spots in your model that have some problems are these areas at the ends here:



If you zoom in closely to those spots, you can see that instead of just being a simple structure in those spots there are some tiny little slivery bits in there:




Those are what are messing up the fillet, also in the bottom of one of those areas is a little gap which meant the object didn't quite get all joined up into a full solid.

I've attached a fixed up version of your model - to fix it I drew in some lines at those ends, and moved the line inwards slightly and then just trimmed off those little slivery parts to make clean ends instead. Then I used Construct > Planar to fill in plane caps in those spots, and also I noticed a couple of edges that were fragmented into more than one segment instead of being a long edge, I used the Merge command to get those glued together into long edges.

This version should now fillet ok.

- Michael

Hi Michael, I just worked through Burr's recommendation to Rebuild and adjust the points. It worked.

I saw the slivers and gaps and could not figure their cause. Burr explained that. I will check out your file.

Good advice here and thanks to all.

Leonard

"""""""Good lesson there: use Show pts to check the curves *first*."""""""\

Not really "show points" as that wouldnt really show you what you are looking for. What you are looking for are "Seam edges" that when modeling later, if you try cuts that intersectin and out and skim at very small values, will make it hard to work on your model..

So, if you just extrude what should/could be a single contiguous curve and the surface has a seam in it, then you can find these easier...And rebuild them.

The other thing to note about rebuilding curves though, is that you want to look closely as too open of a tolerance will actually be changing the curve! ALso, a downfall and reson NOT to rebuild all the curves, is you will be making a light curve, with maybe 5 points in it, contain possibly hundreds of points!! Which makes the surface heavier, and can compound the model to be unnecessarily heavy..

Use it where you NEED, but not overdone on everything! IMO

Burr,

> So, if you just extrude what should/could be a single contiguous curve and the surface has a
> seam in it, then you can find these easier...And rebuild them.

So, I will extrude the curve to find seams.

> ALso, a downfall and reson NOT to rebuild all the curves, is you will be making a light curve,
> with maybe 5 points in it, contain possibly hundreds of points!!

I noticed that.

All good points. I have to rework that object now and will keep this in mind.

Thanks.

Leonard