what’s the approach/command to add a limited length fillet between the intersection of two surfaces of revolution. see attached image. my objective is to add a fillet from the horn’s vertical tangent on both sides of the intersection…….
Art Smith
the new filletsrf command in v9 will do a wonderful job on this- if you don’t have it, give it a try, or post your file with your fillet spec and I’ll run it for you and post the result.
here is a quick look at some similar geometry-
if you want something more specific, you can always pipe trim
see video-
this is the result of a pipe trim / blendsrf with 3 profiles -
Trim it off with a line or an isocurve.
set filletsrf to not trim, then work with the resulting geometry as needed.
trim with the crv switch (run trim, then type crv, then hit enter, this allows you to use surface edges as trim curves)
Thanks!! attempted “trimming” the fillet created by WIP 9 and it seems like the number of questions I have doubled…. trimming the fillet with a cylinder is easy enough but it reveals a massive wound from the filleting process. the basic surfaces are all surfaces of revolution so easy enough to “repair”. that said I’m concerned about the definition of the required patch; as best I can see only two of the four sides of the patch are known?? lest it get lost in all of the questions, the fillet inside the horn is exactly what I’m looking for; just need to figure out the 90 degrees from the top of the horn to the external vertical tangent. and of course the repair of the external wound to yield a water tight surface……
Art Smith
Just do it like @theoutside said. Fillet without the trim option, and then trim manually.
Its not 100% clear to me what you are describing, but is either of these what you want?
horn.3dm (897.2 KB)
Here’s the version with patch:
I made two different sides:
elliptical intake horn for Weber 32-36 R9_patch.3dm (3.4 MB)
You made the second version just because Rhino wip9 has the new patch tool 
Thanks again guys, turning off the switches yielded Major Progress!! hopefully one more question regarding the use of “VariableFilletSrf”; “Help” provided no clues…… image below documents progress from turning off the switches (ie: Progress) and how far I got with “VariableFilletSrf”. seems like I should be prompted for a starting and ending location (and an ending fillet radius unless assumed by default to be zero)………………..
Art Smith
Try FilletSrfToRail in WIP: It works with History, so what you need to do is make the fillets for each surface and then start tuning the rail. This is not 100% tangent but getting in the direction:
elliptical intake horn for Weber 32-36 R9 FilletSrfToRail.3dm (4.9 MB)
That would be my suggestion also. VariableFilletSrf has very limited value and is unlikely to do what is needed here.
That said FilletSrfToRail has its problems also.
Have you looked closely at the first fillet where it meets up with .375R constant radius fillet. At that end the surface folds back on itself making it not even close to being tangent. Turn on Curvaturegraph for this surface to see.
Also the last fillet doesn’t quite make it all the way to a point. That one can be fixed with SetPt
Yes, FilletSrfToRail wants a curve, but the curve is not the intersection curve of the two surfaces that are being filleted. The curve is where you want the fillet edge to land.
Using the example Gijs posted this is the curve:
The way I would make a curve for FilletSrfToRail is to first make a simple curve that you can project onto the surface with history enabled. Then use the projected curve to make fillets with FilletSrfToRail. You can then point edit the simple curve and the projected curve and fillets will all update.
here is an example. Turn on control points of the Magenta Curve and as you move them the fillets will update. You can go to a front view to see where the projected curve will land on the surface.
FilletSrfToRail_curve.3dm (508.8 KB)
Jim-
HUGE thanks!! not the engineering solution I was expecting but it will due
Art Smith
Maybe supply a sketch of what you really want.
@jim The pointy fillet can be corrected by iterating the rail I found, but the folding can’t. I’ll make a YT for this shortly. The other thing I noticed is that it has a tendency to (almost) stack control points at the ends. So yes, this solution is far from perfect.
Question to @artesmith does it need to be a true fillet, if not, I would go about this completely differently.