Round top and extended round base model for 3D printing or milling

[WhoCanDo]

I thought this would be easy by creating two objects and subtracting solids, but now I find that the shape made from Nurbs ends up as a group and can't be subtracted.

 

Therefore, I'm calling for ideas please.

 

Here's what I am starting with ..

 

  The oval is at level 0, and the circle is 90mm higher. This circle diameter is 60 and the oval is 77.49 if anyone is interested.

 

After several attempts, I found that the shapes had to be converted to Nurbs and the with Loft Surface tool, I could make this "solid", so I thought ..

 

 

With this and another, which is smaller so I can make a 5mm wall thickness, I wanted to subtract solids to make a tube, but it's not a solid, it's a group of Nurb surfaces.

 

I obviously went down the wrong track, so any help would be appreciated.

 

Edited May 28 by WhoCanDo

[Benson Shaw]

I would try to convert your initial lofted solid shape to Generic Solid. Or also try starting with multiple Extrude of the Oval and Circle (instead of the Loft) to create a different version of your solid. Apply the Shell tool to hollow it to the “pipe” solid with specified wall thickness. Generic Solid again if necessary. Result should be a solid which can export as STEP, or STL for print. 

Not sure if the Loft or the Multiple Extrude will make a better Generic Solid and subsequent export for a better print. 
 

Post back if no joy. 
 

-B

Edited May 28 by Benson Shaw
AFK

[WhoCanDo]

The loft is 1024 Nurbs and I can't get them to add.

 

I tried Generic Solid but it rejected the objects.

 

I tried Adding Objects but it rejected that too.

 

I'm not sure what you mean by Multiple Extrudes because there would have to be thousands to create a smooth surface.

 

The Shell is the easy bit LOL

[Tom W.]

Model > Multiple Extrude... command

 

https://app-help.vectorworks.net/2024/eng/VW2024_Guide/Shapes2/Multiple_extrude.htm?rhsearch=multiple extrude&rhhlterm=multiple extrude extrudes

[WhoCanDo]

Thanks Tom.

 

Not having done much 3D stuff, you help is wonderful.

 

However, if I set the Shell tool to 5mm inside, how can I get it to punch through the bottom 5mm ?

 

Is the only solution to make the object higher and subtract solids to clip of the bottom 5mm ?

[Tom W.]

If you use Option-click to select both the top surface + the bottom surface of the extrude then run the Shell command you will end up with a hollow tube which is open top + bottom: is that what you mean?

[WhoCanDo]

Nice one Tom.

 

That will keep me going for quite a while.

[Kevin McAllister]

12 hours ago, WhoCanDo said:

With this and another, which is smaller so I can make a 5mm wall thickness, I wanted to subtract solids to make a tube, but it's not a solid, it's a group of Nurb surfaces.

 

When you lofted the two curves, was the Create Solid checkbox active? If not, it will solve your issues.

 

Kevin

 

 

[WhoCanDo]

Yes, but I couldn't "Closed" it. The Close button would not stay ticked even though it was not greyed.

 

The loft created multiple Nurbs and grouped them. It did not merge them into one solid/surface as I was expecting.

 

[VIRTUALENVIRONS]

A problem may be in how the curves were created.  This can be an issue.  The curves have to be matched to some degree.

 

I gather you want to make the shape indicated and have it hollowed out.  If you want to, please post the two curves you have constructed.  I can have a look tomorrow.  

 

 

 

 

[WhoCanDo]

Hi Virtualenvirons,

 

Even though I have created this part using multiple extrude, your questions are valuable for other components I need to draw.

 

As per my initial post, the circle is 60mm diameter and the oval is 30mm radius and 77.49mm long. It's actually a slot. The finished height is 90mm and the wall thickness is 5mm.

 

I would be interested in reading your step-by-step method of creating the same object with Nurbs and Lofting.

Edited May 29 by WhoCanDo
Clarification

[Kevin McAllister]

4 hours ago, WhoCanDo said:

Yes, but I couldn't "Closed" it. The Close button would not stay ticked even though it was not greyed.

 

The loft created multiple Nurbs and grouped them. It did not merge them into one solid/surface as I was expecting.

 

It's the Create Solid checkbox that creates a solid object, not the Closed checkbox. Your curves also need to be going in the same direction.

 

Kevin

 

[WhoCanDo]

Interesting Kevin,

 

After a bit more testing, and you suggestion of "same direction", I think I understand my error.

 

Because the circle wouldn't Loft, I changed it to a polygon, but because there was no "convert to polyline" tool, I also changed the polyline to polygon to match.

 

Big mistake.

 

They wouldn't Loft either, so I changed them both to Nurbs and that's why it lofts to a group and not a Generic Solid.

 

I will have to remember that the polyline should never be changed to a polygon before changing to a Nurb, but a polyline or polygon can be changed directly to a Nurb.

 

[Benson Shaw]

@WhoCanDo  Here is a little tutorial on the NURBS and Shell.  Sounds like you area getting there. This little tutorial might help some.

 

In the Loft steps, I added the alignment to make a straigter shape.  Another approach is to use the Ruled option.  Align as desired.

 

In the Shell steps, when picking the surfaces, click the 1st (top in this case), then, to extend the selection,  press/hold Shift and Option to acc press the occluded surface at bottom of the figure.

 

HTH

-B

[VIRTUALENVIRONS]

9 hours ago, WhoCanDo said:

your questions are valuable for other components I need to draw.

Hi WhoCanDo, nice handle.  You have great information on this thread already.  There are a few options to create this object, but it is a good opportunity to refresh "matched curves".

 

 

 

[VIRTUALENVIRONS]

@WhoCanDo

If you go to my YouTube channel (that is not monetized) there are tutorials that range from intermediate to advanced, plus NURBS demos. 

 

3D printing.  

This cone will likely print OK, but you can't count on that for more complex objects.  Vectorworks can produce very complex objects, but the surface normals get pushed around.  I send to C4D and activate "Backface Culling" to check surface normals.  The program has tools for fixing normals, but still it can be trying.

 

The Christmas tree below was modelled in Vectorworks and 3D printed, but it took a lot of work in C4D to fix the normals.  Then I had to re-import back to VW's to create the printable shell.

 

[Kevin McAllister]

2 hours ago, VIRTUALENVIRONS said:

There are a few options to create this object, but it is a good opportunity to refresh "matched curves".

 

Very useful tutorial! I tried various ways to get the number of points to match myself, but I didn't know this one. Your video also reminded me I could use the Rebuild NURBS command to get the number of points to match.....

 

Kevin

 

[Benson Shaw]

Apologies to @WhoCanDo.  This thread now includes a bunch of NURBS nerds wading into the weeds.

@everhyone - The various ideas, challenges, problems and methods presented here illustrate that the NURBS model from same source curves can represent several or many different shapes depending on methodology.  So, which is the right one?

 

• Curves of different direction can produce a crazy shape, often squinched in the middle. Or possibly failing completely.
• Matching up curve direction can produce a different shape. Usually more like what is envisioned.
• Adjusting the alignment produces yet another surface/solid, but with more coherent isometric curves (those highlighted lines/curves shown when the surface is selected)
• Adding element of matched vertex count produces yet another shape, perhaps with better isometric coherency.
• Matching the vertex count via Rebuild NURBS (Thanks, Kevin!!!) can foil the alignment (ie count does not always divide the curves lengths evenly nor start at convenient point) and produce yet another shape.
• Splitting the curves so that alignment of loft start points is precise increases coherency, but at the cost of needing to add surfaces later. No biggie, but yet another shape.
• Or, (Hats-Off-To-Paul!!!), duplicate a 3d Locus in equal number along each curve (or split the source curves as demonstrated), then trace a new curve through the loci, makes a very coherent surface. But at cost of several more steps/clicks.  Probably worth it, usually, for yet another version of the shape.

Then there is that little problem of the wobble when the original source curves are remade by the Rebuild NURBS or the trace through a series of loci.  Zoom in to see that the new curve is not same as the source curve. More vertices gets closer. Or does it matter? For visualization, not at all. But fabrication requiring adherence to some spec or some precision, air tight joints, etc may be deficient.

 

Then there is that problem of the vwx NURBS facets! I really wish we could get that one solved. Is that just a vwx screen graphics problem or is the faceting incorrect math/representation.  If object with those facets is printed or machined from the faceted vwx curves/edges/faces, do the facets manifest? Or does the translation to the machine software reload the intended curvature??

 

Or, this particular item could be made in yet another similar shape without NURBS via Multiple Extrude and Fillet Edges.

 

Soooo, which one is the correct shape? What is the vision or specification? or will any of these do???

 

I'm laying out some of the differences and issues for discussion. Not critical of any of the approaches.

 

-B

Edited May 30 by Benson Shaw
Need a rain walk

[EAlexander]

This whole thread makes me happy. You're all nerds and I am here for it! 

Great info being shared. 

[VIRTUALENVIRONS]

9 hours ago, Benson Shaw said:

I'm laying out some of the differences and issues for discussion. Not critical of any of the approaches.

 

Hi Benson, lot's to think about.  We forgot one, just "Multiple Extrude".  see below.

 

This is an excellent topic to continue and I hope it does.  It appears that VW's itself only pushes NURBS at the lower to intermediate level, even though it is capable of much more.  The question is.....why?

I believe the answer lies in where the money is.  The money is not in Zaha Hadid Architects, but in everyday Architects, Landscape designers, Venue design, etc.  Hundreds of thousands vs "the few".  I can understand that.

The advantage that VW's has over other 3D programs is the hybrid 3D methodology.  You can design a house in 3D with lower intermediate 3D skills, but in the end, there is a penalty to pay.

Using hybrid tools, even if you are an expert, it can only produce advanced intermediate designs.  So expert in > advanced intermediate out. 

 

NURBS is a nice to have for VW's, but not something they are willing to put money in.....yet.

 

 

Edited May 30 by VIRTUALENVIRONS

[Benson Shaw]

@VIRTUALENVIRONS thanks for that Multiple Extrude example. What were your source shapes? I know it should work, so tried early on with a circle and the same oval I used in my NURBS example.  It totally squinched. Similar to the misaligned NURBS. Rotating the circle helped a bit. Splitting the sources (converts them to Polylines), then compose and extrude also was better, or extrude the halves and Add Solids, but never achieved your simpler iso parametrics. Also does not always even produce a solid!  What’s the secret?

Seems @Kevin McAllister demoed a method to realign multiple extrude sources a few years back. ???

 

-B

[VIRTUALENVIRONS]

27 minutes ago, Benson Shaw said:

What’s the secret?

Hi Benson,

Not a big secret, it was just take a second circle, convert to polygons and then use the reshape tool to move the polygons.   I will not produce a smooth surface though, it was more of a joke.  Although, machine or printers can smooth it over.

 

regards.....Paul