A few shots to show the issue.
The first is a render veiw of a blend that was matched to the joint suface. I ran match surface on it because the intitial blend was showing a discontinuity. Maybe the issue is the rendering.
The other is an anomoly that showed up after completeing an object that was showing clean.
BlendRender.zip (1.7 MB)
Windows 10 is telling me your BlendRender.zip file is invalid.
Turn on the FlatShade option so you can see the render mesh facets without the viewport smoothing. That bulge could easily be an ill-fitting render mesh.
The borderless shaded square looks like it might be a bum render mesh.
Does your file have any bad objects in it?
It’s pretty common for bad objects to generate bad render meshes.
I looked at your file in 7Zip and you used an illegal character in the file name. question marks and asterisks have special meaning in Windows so can not be used in file names.
The untrimmed square was indeed a render mesh on a bad surface.
I think we’ve gone over fixing bad objects before.
If not, here’s a link:
http://wiki.mcneel.com/rhino/badobjects
I think the bulge you’re seeing is the render mesh as I described.
Here’s the Flat Shade view I mentioned:
Here’s a tighter render mesh:
Hello JKayten,
Analysis shows you do not have even G1 continuity on that edge you’ve indicated in the second picture, and light lines show a very lumpy surface indicated by the arrow in your first picture. Try untrimming your edges and not skimming the edges of the extrusion you’re carving out so close to the egg shaped housing, it’s leaving Rhino with a mess to try to figure that blend out. If you’re going to Boolean it’s not so good to try to keep some generous separation on edges and surfaces rather than running those so closely together, you aren’t making that easier for Rhino, it’s making it more difficult.
You mean I need a larger gap for the blend?[quote=“OSTexo, post:4, topic:34183”]
If you’re going to Boolean it’s not so good to try to keep some generous separation on edge
[/quote]
I ended up redoing the bit with a simpler shape boolean operation and using fillet to get close to what I wanted.
Is there some aspect of the point contruction of the two surfaces that effect the blending smoothness?
Is there a function like show edges that could be left running for bad objects?
There isn’t. What I recommend is to run CheckNewObjects so Rhino constantly
checks. Then when it happens, you can deal with it right then instead of
having to clean up later.
Hello,
I think the gap is fine, it’s the surfaces you’re trying to connect that are an issue. I suspect you’ll continue to have problems in the area you’ve indicated by the arrow in the second picture based upon the small surface you’ve cut away from the egg shaped large surface, That smaller inner surface wrapping around near the base does not look good at all. Try starting with a better inner surface that doesn’t have those wings at the base of it and allow Rhino to do its job in creating the blend for you. I should have a little time this coming week to tinker with procedure. Do you happen to have a 2D plan of this motor housing you’re trying to create? Thanks.
Hello,
I’ve run through a few things and I think I have a decent procedure that would work for this. I’ll attempt to post a video this week.
Hello OSTexo,
Thanks for your help! I realized I was cutting transitions in the surface that would be done with a simpl fillet operation (in this case it was good enough) But I still want to learn more blending approaches so I’ll look forward to you vid.
I’ve no plan for the fan, it’s been modeled over some photos and I’ve the actual item to make exact measurements with.
Nice work, Thanks much for the help.
The vid confirmed what I suspected - trying to use the cutting tool to do what the blend would do better.
I’m still making things more complicated than necessary but I can see improvement. After discovering the untirim function, I’m now able to resuse surfaces by simply extracting a portion untriming it, and making new cuts. I found that I can use the gumball tool to line up control points in a particular axis by clicking in the scaling square and setting it to zero. This only when the absolute location of the aligned points is not critical - otherwise I’ve access to setpt on my Popup menu.
I’m also inclined to create revolved solids and then split them. Maybe it’s better to create partials that are a bit outside the boundries and cut back.
My goal is to make every process as acccurate and efficient as possible ( I grow weary of stepping back to correct something). You mentioned that a curve was racked. That is the bane of my work thus far!
I’ll probably go back and rebuild the upper housing - again. 
Thanks again.
That’s some great advice John, thanks.
OSTexo,
That video is really helpful. It will improve also my workflow in many cases.
