Great sample model!

Thanks for the infos!

So the 3 keys are Iso - NetWork - Blend! ;)
in waiting an hypothetic video! :)

An idea of time for modeling the object above ? (with technic assumed)
And have you try to transform it in a "solid" in Moi ?

Always with the incredible free SimLAb Composer lite ;) 1 second render :)

"So the 3 keys are Iso - NetWork - Blend! "

The three keys are 'Project', 'Blend', 'Network'. The first problem is to get fair curves on the surface. In 3D mode, you can 'draw' on a surface, so long as you are in 'Object' mode and have 'On Surface' selected. Then, every point that you pick will be on the surface; but you will notice that if the picked points are very far apart (and the surface has much curvature) the line seems to disappear. This is because the curve is finding it's own way between points and is not on the surface. (BTW, for those unfamiliar with the term, 'Fair' refers to -- I will call it -- constant curvature. It is very different from 'smooth'. The term comes from the building of ships and yachts. Take a fiberglass hull and paint a line on it, from stem to stern, which looks straight from the side. Now go to one end and sight down the line. If the hull is not 'fair', it will look wavy. The surface may be quite "smooth", but if any line along the hull looks wavy, the surface is not 'fair'.) When you draw a curve this way, it will not be fair. What you need is a fair curve, on the surface. To get that, draw a curve on a plane (2D) and use as few points as you can get away with. You can easily move those points around to make the curve fair. The curve that you drew on the surface will only be a rough guide. When you 'Project' that 2D curve onto a complex, 3D surface, you will get a fair curve that is on the surface (because the projection will use as many points as necessary to make it on the surface). A very neat function of 'Project' is that after the projection, you can move the points on the 2D plane, and the curve on the 3D surface will adjust to the change! With this trick, you can fine-tune the projected curve and retain the fairness. (There is one case where this doesn't work: If you project onto a cylinder or anything like that, you will get two projections, on on each side. In this case, you can't adjust the curve after the projection. I guess that manipulating two curves at once is too difficult.) Once you have the curve that you want on the surface, do 'Select Points' and look at it. If there are a huge number of points, this may be telling you that the surface is not very fair and so many points are required to make the curve conform to the surface. You might 'Rebuild' the curve with fewer points, but if you reduce the number too much, you will have trouble trimming the surface. And while you have the points showing, zoom in on the ends and move the end-points to the intersection of adjacent surfaces, or to the edge of the surface to be trimmed. This is an important step, as it will eliminate a lot spurious end-points which can give you much trouble when do other operations. One more point on using 'Project': You may assume that you have to draw your 2D curve in one of the orthogonal views. But in many cases, that will not give you the result that you want. You need to project more or less perpendicular to the surface. So you will often have to make a plane that is more or less perpendicular and draw on that. (I thought that I would have to reset the 'C Plane' to this new plane, but usually 'Project' is smart enough to know what you are doing and will just do it. If it doesn't want to project, then reset the 'C Plane'; but 95% of the time, that's not necessary.) I've explained this at length because you have to get this right before you use 'Blend' and 'Network'. 'Iso' is certainly helpful in making the cross-sections that 'Network' needs, but I would call it a secondary, not primary function. Play around with this and see how it works for you. If you have trouble, come back with a question.

Sorry, I forgot your second question: How long does it take to make a model like this cylinder? I don't really know. I had only done one other model with MOI (or NURBS) before I started this cylinder, and I didn't know what I was doing. (I do have a lot of 3D experience, going back to the early 1980s, but that was with polygons, and NURBS is very different.) Learning is a slow process! A lot of that early work was poor and I had to go back and fix many things. There is still much on this model that can be better, because I accepted things that weren't really right, but were close enough that the errors would never be seen at the resolution of 3D printing. I want to say something about design. Companies like 'SolidWorks' teach people to do everything in 3D and then make 2D drawings from the 3D model. Except in simple cases, I think this is insane. I do all the design work in 2D (using 'Q-CAD'). Then I can import DXF drawings into MOI and build the model from these. It is very easy to make small changes in 2D; e.g. moving a screw location. Doing the same thing in 3D is very time consuming. I haven't tried to make a solid of this, but you can try it. I rather think that it is too complex.

Many thanks for the very detailed answer(s)!

So that is your "first" try of complex Moi object ? Very convincing result! Bravo!

You don't speak about the projection "nearest point" option - does this will be useful or not in your process ?

When I speak about "3D solid" result it's just when you "Join" all surfaces Moi makes a unic "Solid" waterproof (if surfaces are well build)
Indispensable for 3D Print or future boolean operations between volumes!
So maybe that takes many or few time or not - or maybe that is not possible because some problem are always present.

For your object that is one minute - and result is not a solid but stay "Linked surfaces"
So maybe some little adjustments are necessary for have a 3D printing object...
But like is it's yet pretty cool for just render images or maybe animation.

Do you know the native ExplodeMove function ?

Press Tab and write ExplodeMove (with or without Capital(s) anywhere but without space) or by shortcut making (on the 2nd column)

That can be help...to understand the surfaces! ;)

I'm afraid that my explanation yesterday may have done more to confuse than inform. I will address this in the following post. Now, I will tell you why this model can't be turned into a 'solid'. I made this model for display only; for example, to render as you did. This model will be changed for 3D printing and casting. For example, if you look, you will see that the screw holes have no bottoms! Obviously, that won't make a solid. I should have told you this; I'm sorry that you wasted time on it. Also, on the model to be printed, I have to add material to all the surfaces that will be machined after casting. This model is just to look at.

Here is a picture that will help explain one of my methods. The job here is already finished, so you will have to imagine that the fillet in question is not there, and the red curve is just a rough idea drawn on the surface. Because of the angle, there is no way to project onto this correctly from any of the orthogonal views. So after I've drawn the rough curve, I adjust my viewing angle to that which will work best for the projection. I then draw a line that corresponds to that angle (that's the green line almost hidden among the selected lines). I move that line away from the surface and then I make the plane perpendicular to that line. Next, I copy that line to several points along the rough curve. The lines selected are those lines, which I have extended to fall on the plane. Now I can draw the blue curve between those points. After drawing that curve, I delete the selected lines -- they are no longer necessary. Already, this method washes out a lot of the irregularities of the rough curve, but if necessary, I move the curve's points on the plane until I have a fair curve. Now I can project that curve onto the surface. As I said, even after it is projected, if it doesn't look quite right, I can move the points on the plane again and the projected curve will automatically follow. This is very neat. When I'm happy with the projected curve, I 'Show Points' and move the endpoints to be certain that they are precisely where they need to be. I then use that curve to cut the surface. I'm afraid that this sounds awfully complicated, but when you've done it a hundred times, it goes smoothly. One thing that this method permits is a gap between surfaces that can vary in any way that you choose. It doesn't have to be straight or tapered. It can be narrow at the ends and wide in the middle, or whatever suits the model. I want to mention something else. When you use 'Blend', the bulge factor should be different depending on the angle between the surfaces. But what do you do when that angle changes over the length of the 'fillet'? Simple: At the wide-angle end you will want a bulge factor of maybe 0.8. At the end with the more acute angle, you will want a bulge factor of maybe 1.2. So first, blend the edges at 0.8 and make a cross-section (usually with 'Iso', or just turn the end of the blend into a curve). Delete that blend. Do another with the bulge factor at 1.2. Make a cross-section at the acute end. Delete that blend. If you want to be cute, do another blend at 1.0, and make a cross-section in the middle. Delete that blend. 'Blend' forces you to chop up a fillet wherever there is a single edge. You can now 'Merge' all of the edges that you trimmed to accommodate the 'Blend' tool, and 'join' all the edges so that you then have only two long curves. Select those and all the cross-sections and do 'Network'. Do you get this? You can make fillets that vary in width and vary in bulge-factor and that cover several surfaces! In other words, you have complete control over what you get. Yes, there is some work involved, but there is no way to automate this process and retain this control. And now you see why I say that doing 'fillets' in MOI is a strength, not a weakness.

Here is another model that you can play with.

Hi Tim,

Thanks for explaining!

<<that you wasted time on it

No problem... I just load it --- Join it (no solid) --- ExplodeMove it and render! ;)
All that take 2 minutes! ;)

I will study your last explanation and model...as soon as i have 5 free minutes!

Stranger things indeed! :)

Here is another example. You can see that there are several 'parts' which do not come together in any way. There forms are dictated by their functions. But all these 'parts' have to come together to make one part. As I said, the problem here is nothing like a 'fillet', although the end result often looks like a 'fillet'. This sort of a problem comes up in my work more often than the 'fillet' problem. And when confronted with something like this, the question is: How do I make these 'parts' conform to one another. Let me be perfectly frank and say that I can very seldom see how this should work. So I need a method, like an algorithm that let's me me begin in the dark and slowly come to the light. In this example, I began by making the surface in the center, which goes from a flat plane on top to an ellipse at the bottom. I used 'Blend' to make that -- but first I had to extrude the ellipse at a certain angle that would give me the correct form. With that surface done, as you see here, I went about "drawing" lines on the surfaces of the other parts. The blue lines shown here are not the first or the last that I drew. I draw some lines, and then rotate the view around and look at the whole scene from different angles. My first effort is usually quite poor, but knowing what won't work is information leading to the solution. I keep refining these rough lines until I can 'see' how the connecting surfaces must be. When I finally know what I'm doing, I apply the method that I previously explained, to go from these roughly drawn lines to fair curves that lie on the surfaces. With these I trim the surfaces. Then I use 'Blend' and 'Network' to fill in the gaps. 'Network' is a fantastic tool, but you have to provide enough information for it to work without deformities. 'Blend' is the primary tool that you use to set up the network of curves (the information) that 'Network' needs. When you master this, the results are wonderful.

I gave you a problem which many people might find impossible to resolve. So here is how it turns out.

And natural boolean between volumes don't can give some result ?

Does all that is real pieces or imaginative stuff ?

First, as I said, the "parts" here are dictated by their functions. One of the reasons that I posted this is that a lot of what is done with MOI is aesthetic -- that is, the object is to make something Look a certain way. My work has to be turned into machine parts that have to function, and not just look nice. That object that you did the rendering of is part of a piston, which will see 9,000-rpm in that cylinder. The problems then are quite different. One "part" has to do one thing and the next "part" has to do something else. But these "parts" have to come together into One Part. Without understanding what the engine does, how it operates, you can't appreciate Why every detail of this cylinder must be very nearly as it is. And when I put these "parts" together, I can't compromise their function in order to accommodate the limitations of the software I'm using. And the beauty of MOI is that I don't have to compromise. But there may be other ways of getting the job done. I haven't seen anyone else solving the sorts of problems that I have to solve, so I developed my own techniques. I would be very happy if someone could show me an easier, faster way to do this. But what I've found on the Forum are people getting stuck doing things that I think are trivial. I must point out that in this last example, when I look at the "parts" that I must bring together, there is no one solution to the problem. This is why I have to draw a bunch of lines and keep trying different ideas until I find something that works. And solving this problem doesn't help much when I get to the next configuration -- every arrangement is different and requires a unique solution. But my method always works.

Many thanks for your always very detailed explanations!

PS Can we say that your method is a little like the option "Planar Sections" of the Blend function ?
http://moi3d.com/forum/index.php?webtag=MOI&msg=6790.35

I haven't used the Planar Sections option -- but I thank you for suggesting it! There are still some complex geometries that take a lot of time to get right. The Planar Sections option might help in such cases. The main technique that I wanted to offer is that where I can draw rough curves on a surface in order to 'see' what I want to do next. Then, use Project -- from an appropriate plane -- to get a fair curve that is actually on the surface. That curve is adjusted and used to trim the surface. All this must be done Before using 'Blend', as you have to have corresponding edges to work with. I also want people to understand that the limitations of 'Blend' and 'Network' can be largely overcome by using both of them together. There are several other tricks that I use but did not mention. 'Network' has a tendency to curl the surface as it approaches an edge. To fix that, I usually use 'Iso' to give me some curves that lie on the not-quite-right surface. I often 'Rebuild' these curves, reducing the number of points, which washes out a lot of minor distortions. Then, I adjust the points on these curves, near the curled edge, so that they are tangent to the surface. The trouble with 'Network' is that it doesn't take into account the form of adjacent surfaces, so we have to provide enough information so that those intersections will be tangent; and this is what I'm talking about. When I have those new curves corrected, I run 'Network' again and the curl at the edge is gone. I didn't mention a problem with 'Blend'. You have to break up a 'fillet' at every intersection, as you cannot add edges (as you can with 'Network'). And when the geometry is complicated, those short sections of Blended 'fillets' don't fit together well. They may look okay from a distance, but it you zoom in, you will find that there is a gap or the edges overlap. But if you use those Blends only to give you cross-sections (which are properly tangent to the adjacent surfaces), then delete those Blends and run 'Network', everything fits without errors.

Thanks for these extra infos!

Just a little thing ;)
The position of the click of the Blend function gives not the same result!
That was the same for the surfaces in the past but as that was some perturbating i believe that Michael stop it!

Only subsists that for the curves! ;)



PS Of course i have forgotten the normal way ;)

You asked about 'Joining' the surfaces of the cylinder model. As I said, the model shown was just to look at. One thing that I did in that regard was to make curves of all the edges that I want to be seen as edges; then I gave them a different color. This looks much better than otherwise. Of course you want to hide all the edges of surfaces that should look continuous. But when you hide the edges, the edges that should look like edges become sort of fuzzy. To change the model for 3D printing, I eliminated all those curves, so that I had only surfaces. I also eliminated all the 'holes' (screw holes) which were open on the bottom. I then 'Joined' the surfaces. Only one had a problem! Think about that: More than 1400 surfaces in this model and only one problem. That surface was a simple one and I redid it in a few seconds. Then the whole cylinder was one joined-object. Let me say again that my method is to 'Project' a line onto a surface. Then, I move the endpoints of that line to the intersections of the surface. This eliminates a thousand errors that prevent the edge of one surface from matching the edge of the next surface. Only then do I use this line to 'Trim' the surface. Also, as I said, 'Blend' will frequently mismatch the edges of fillets, where more than one 'Blend' is required. Using 'Blend' to make cross-sections, and then using 'Network' to build the fillet eliminates those errors. When I started with MOI, I was doing what I thought should work, but when I zoomed in, I found too many mismatched endpoints. How could I avoid these? I found that the best way was always to begin with a line, adjust the endpoints, then 'Trim'. This is how I produce more than 1400 surfaces without errors.