networkSrf asks for another curve so what is best approach on simple shape?


see attached, needs the two rasters as well for the picture frame then you can see the objects shape I am trying to recreate.

I thought best use network curve to surface the sausage shape, but it asks for another closed curve no doubt lengthways.
sweep2rail I tried which would do all but the ends but was not the right shape despite trying a few options, ends I am unsure how to deal with anyway.

I have drawn the two shapes I know the shape of, so to have to try and draw a third curve which I would only know the shape of AFTER the surfacing was done has me stuck.

Would making this shape be best done this way, placing fillets between the sausage and the cylinder ?

or should I make more curves from the cylinder and do the whole thing with networkSrf ?

I feel that might involve even more deducing what the end result is before actually creating it, sort of need a crystal ball to create more curves.

Sometimes you have to try it one way and hope you get the effect you are after before committing to brain ache !

Could someone create this and indicate steps they took please.

Knob best approach.3dm (172.5 KB)
needs the two rasters, also uploaded though I didnt want them showing up, they are for the file not for viewing here, good job they are not BIG file size. (how does one attach images and stop them showing ?


If you split out one quarter of your thumbscrew (looking down the spindle) and delete the rest, then curve network will work with what you have already (all open curves). Then mirror the resulting surface to get the remaining three quarters and join them together. (It’s usually easier and quicker to work on one segment of an object where you have symmetry.)

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Here’s one way - I am making stuff up a good deal but if you can look at the actual object you can tune to taste. The basic premise is that, likely anyway, the thing was originally laid out as tangent arcs and so can be built that way… could be wrong.
Knob best approach_PG.3dm (366.2 KB)


Hi Pascal,
The item was 70 yrs old.
that is gorgeous and perfect, :heart_eyes:how did you do it ?
I dont suppose you saved a video whilst making it ?
Such would be so useful to view, great to have on the tutorials etc.

I tried for the cylinder and managed the sausage but filleting between the two gave me nothing of use, far removed from the correct shape you have.

Did you start with the sausage and cylinder ?

I see you approached the end caps by sweeping a profile around an apparent outer arc and a very small inner one at either side, am I right ?

I could learn so much seeing shapes like this made in a video.

Problem lies when I have to get this done for a deadline. I recall surfaces are best with 4 sides. couldnt see how to give this such. I split the end into four segments but it looked like a balloon inflated in a wire basket , the wires being the edges of my 4 segments. each had 3 sides.


Hi Steve - here is a version with ‘keys’ for how the surfaces are made.

Knob best approach_PG_Key.3dm (626.3 KB)


**Dear @Steve1 , dear @pascal **
Today i discussed your Knob with my students to show them this great forum.
It s a very nice Object - thanks for the post.

I would suggest the attached alternative Versions.

Please also notice, that the initial posted file as a rough (0.01) unit Tolerance.
It should be Template “small Objects Miliimeters” -> 0.001 mm Tolerance.

the “simple Version” is just an revolve in the middle and a simple polysurface
but with tangential crv-Setup (check the crv Layers)
both surface-Sets are combined with a filletSrf. (extend=No important!)

with the other version i use a sweep2 for the transition between the radi.

best from zurich. tom

Knob_alternativeVersions_Tom.3dm (447.9 KB)

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Nice approach on the sweep2 version @Tom_P