What is best method to surface this structure if Network surf is a bad tool?

Rhino Rhino for Windows
1

Hi,

a nice simple task but what is best way…

With talk of dont use networkSrf, (adding that to my list of dont use, such as JoinEdge)

I am now unsettled and wondering which parts should be dealt with in which way with the attached structure and with what command.

What was selected and why would be good to know.

Could someone be so kind as to step by step it showing method for each part.

should be a doddle for an experienced user.

I also ponder on how the front portion gets made, the object ends at line shown.

I have extended the base lines to this point should they be of use.

all profiles are in two halves.

maybe it can be done in just two surfacings. side and base.

Its symmetrical by the way…and all junctions intersect. Also all curves are as good as I can get them. alter one and another junction is lost. I ended up using curve edit points as that way only the curve between points can be moved subtly. SoftEdit has a bug as was discovered this week by davidcockey so also cant use that.

I have spent days on this, getting all the profiles (from ancient tabled data) to intersect. Fix one and it puts another out or messes up curvature graph. Its as good as I can get and adhering to original dimensions which are vital.

so is it loft or sweep2 or what, I would have gone for NetworkSrf but such is best avoided I am being told this week.
Network of curves best approach surfacing_f2.3dm (63.4 KB)

Steve

2

As you discover, simply none of the srfs tool works.
The problem is in the curve layout. This layout is, simply, impossible.
I can understand you took long time fixing all the curves, but, sorry, it’s just the starting point, not the end.
A surface MUST have a rectangular layout (topology) so you have to subdivide your curve structure to get as much 4 sides you can.
Specially in the right part, were the horizontal intersect the vertical the layout it’s particularly bad.
You can’t get any perfect solution, you must accept a certain tolerances between the created and the srf,not because Rhino3D is not precise, but because your construction isn’t perfect.
Hope this can help you.

Take a read of this post Modeling a mixer
It has a very similar question.

Bye.I

3

The layout is an actual shape that existed 70 yrs ago, and the 70 yr old plans of that item were found and drawn up. Very lucky to find it in fact. The plans had full dimensions for each of the profiles, and of course they didnt intersect as they were for the construction of a wooden item.
They didnt draw things to suit rhino back then. Finding this has given me its shape which was proving impossible to work out as I had no object to measure.

Specially in the right part, were the horizontal intersect the vertical the layout it’s particularly bad.

Its what the plans give me, they drew this at the time and it would have been acceptable to manufactree methods back then. That right part you refer to was them creating profiles for the more complex curvature going on in that area. There was in fact a 1.5mm step in at this items lower part and fwd area which I have removed to make it easier to model, the profiles were more dense there because of their step in.

As such this cannot be network surfaced, though it looked ideal for NetworkSrf…or can it, I dont need to fillet this thing so could networkSrf be used.

Are you saying that this is even beyond NetworkSrf ?

once per side and another across base, in fact base could be PlanarSrf tool, or trim out of a planar surface.

I am very puzzled that rhino has a tool that we shouldnt use on such…is NetworkSrf just bad for anything to be filleted or just bad full stop ?

I could I suppose create a dxf profile for each of those profiles, and have that printed off and stuck over plywood then cutout and glued together then filled with filler and rubbed down until the plywood shows through.

I cant go adding in more lines as I dont know their shapes.

I am dumbfounded by this, it looked good to me.

but because your construction isn’t perfect.
All lines intersect, all have been treated to curvatureGraph. All were drawn with InterpCrv

What is imperfect about what has been drawn, from the original plans ?

Does it need more profiles, Should I onion skin such and what tool ? Its not a linear development of a curve from one to next. Should I sweep from one horiz curve to next then use isocurve to create another profile ?

Can someone show me what lines need adding (do a photoshop scribble) and indicate surfacing tool for each part.
I dont need to fillet this so it can be more than one surface.

Steve

4

NetworkSrf is an excellent tool when used appropriately.

5

Hi,
Impossible shape…
I couldnt wave white flag at it being that. it didnt look impossible to me.

well I decided to try sweep 2 and networkSrf, seeing that there is no filleting involved.

sweep 2 in three lots , NetworkSrf in 2

Both went very well, no gremlins, whoosh they did it.
Not sure why it was declared impossible. no feedback on what panels to do and how.
I had two minor edits to make having spotted profiles PQ and RS not quite same width as base AB. 0.04mm difference for one and less for another I recall.

What was there to lose.

I say NetworkSrf made a fine job of this.

I did alter the base front with a radiused edge to help things for both, there being no indication in plans what shape was there.

Should I have used Loft ?

attached the results, AND I JUST WENT WITH WHATEVER SETTINGS APPEARED, (probably not the only rhino user that does so, unless one knows exactly what one is doing and what the numbers do, I do know what ctrl points increase does and also try for height maintain on and off)
except I did choose control point 6 for the sweep2rail for the lower portion so as to match the fore/aft isocurves for comparison there.

So how could this be improved now ? Do I see an issue at point indicated, or is it just the screen surface display, Show edges is ok as is show naked edges.

Network of curves best approach surfacing_f3.3dm (807.2 KB)

Steve

6

Probably it’s easier to show you some images:
STEP 1:

STEP 2:

STEP 3:

Hope this help you more.
Ciao

7

Steve,
Please, read carefully what skysurfer has written! He wasn’t criticizing your curves per se. He was saying that creating your form from a single surface is impossible, at least to do accurately, as you yourself have found. What he is trying to tell you is that you that you will have better luck if you break the model up into smaller, rectangular pieces. Then there are various procedures to create continuity between them to give a smooth overall model.
There are numerous tutorials aimed at modeling cars that give great information about dividing there form into smaller manageable surfaces.
Nick

1 Like
8

Nick, Cheers.
Understood.
More tutorials I would love to study, same issue I keep arriving at, must finish this job before training can commence,
Steve

9

Very funny to see that @Stratosfear gave you the same suggestion I gave you here in this other post: VariableFilletSrf only partially selects my surfaces

At the end there’s just one way to do things :slight_smile: