Hello OSTexo,

Look pleas what I made, I rebuild its model from his edges, and you say that there is no way to make it geometry clear like this? Some molding process not allow it? You can trim it any time you like to get those pices but still keep clear geometry.

I made it more clear not only in geometry but also in surfaces, look I mark it in red. He made it with mistakes and got those jagged faces. And it is not becouse some molding process or client wish it is just becouse of absence of modelling skills.









He got all that troubles and horrible geometry becouse he do not follow rulles that I wrote in link I gave.

First, he break first rule, START FROM BIG AND GO TO SMALL. He has to be started from Cylinder and then make all other details but he tried to make Cylinder in the END and got all that troubles! Looks like he started from that bottom spiral detail and after that tried to make Cylinder.
And if even that bottom spiral detail was given by client, hi has to make sylinder absolutley another way... May be like I made it.

Then he break second rule:ALWAYS TRY TO FINDE THE SIMPLEST WAY TO MAKE THINGS.
He started to make Cylinder by joining all that sigments and got a lot of problems. It was not the simplest way but also wrong, becouse it produced jagged faces.

So guys all your arguments looks like you are trying to protect BAD GEOMETRY and absence of modelling skills arguing it by some foggy circumstances.
I can not see any arguments to keep that BAD geometry!


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Hello Andrei,

He didn't break any rules, you just don't understand the model requirement and use. I don't understand why you're making such a big deal over the outside surface of this model, for his application it could be just fine, there is one minor issue on the back side of the outer cylinder which is easily closed up. The model gets a bit heavy at a few places spans wise, but if it was a problem for his application it would make sense that he would ask about resurfacing strategies, no? I'd be curious to see how this outside surface should be done, this model is not nearly as simple as you think. Please attach 3DMs.

OSTexo,
I spend about 8 minutes recording video where I repear all his mistakes... Is it normal to make this kind of model?

He asked for help... I made some suggestion for future and you trying to tell me that his model is perfect and he need no suggestions. He had messy geometry with a lot of mistakes his model has 2 artifacts look here:



I really do not understand you, looks like you want to say that all that horrible geometry and mistakes he made are good path to follow..

.3dm - http://we.tl/kym9sjLY1h

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OSTexo, you are correct, this is for an injection mould. The lower contour is for a cavity split AND NOT NEGOTIABLE.

OSTexo,

And Solid .3dm - http://we.tl/6sSYL9ZMPE

In previows post just joined surfaces, and you can say that it is not solid :)
Now with good geometry of this model you can make absolutley clone of his model in terms of edges if needed (I just do not know what is have to be in this model)

Hello Andrei,

Thanks for proving my point. I didn't even need to run the analysis to see right away that you have continuity defects, they are that obvious. It's clear that the red and green profile lines are not identical. If you're wondering where they are I have attached the analysis screenshot that the software spit out. Interestingly the original file has no continuity defects (I did fix the one naked edge in the back, didn't touch anything else). If any modifications need to be made you are going to have a horrendous time trying to acquire required continuity with that surface layout of yours, it's definitely not an improved clone of the original.

It's always a lot more difficult when specific constraints need to be incorporated into things!

If the outside is meant to be one regularly tapered piece, it can be good to build the bottom edge as a wide ribbon surface (sweep with Twist: Flat can be good for that, seems like you may have already been doing that) something like this:




Then that can be used as a cutting object in boolean difference to slice off the bottom of a longer tapered thin walled base object:




The boolean difference between the thin-walled base solid and the cutting surface will yield 2 divided solids, and the bottom one can be deleted to leave this:




This approach may be good if you're focused more on the bottom surface following a particular centerline path rather than focusing on the final boundary edges of the bottom which in this case come from intersections between the side walls and the cutting ribbon.

Anyway that approach would give more regularity in the outer surface since it would come all from one larger piece. It certainly may not apply if you have other things that are more important than that though...

- Michael

OSTexo,
You have to understand that there is only 2 ways to rebuild this cylinder from his project by do not touch botom spiral deatail, because cylinder has one radius and that spiral detail another. And spiral do not follow perfectly tappered surface of cylinder Look at the picture:



First way is with this artifacts (his):


And second with this continuity(mine):


I do not know what artifacts or continuity is worse in your way.

But to avoid all that artifacts or continuity you have to model it right from the start! - Start from Cylinder! Or made that bottom spiral some how in right way to follow surface of tappered cylinder.


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From Cylinder this way:

His spiral was made with constanat raidous... It is mistake if you want to put it in tappered cylinder and get smooth surfaces...

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OSTexo,
Also if you are so pedant, you better look on his model:


Green Cylinder is perefect one, and it stay behinde his cylinder. As you can see his cylinder is wrong, it is becouse he made that spiral detail constant radius.
To avoid that artifacts that his model has, cylinder must be perfect...
This model have 2 mistakes it has artifacts and it is not perfect cylinder. Also it had messy geometry.
Do not know may be this things are not important for molding :-)

Hi Big,
Here is a method to bring your model in. I did this to give you some insight for possible future projects with this customer/vendor.



So first thing to note is I bring it in as a "STEP" file. My guess is you are having to interface with some existing geometry (Like a mould plug). The existing geometry was most likely made in a Parasolids application (And most definitely a "solid body"). If that is the case, ask to use the STEP format. (I have seen many things like this when translating Parasolids, from higher end apps.

With the model, there is a duplicate surface which creates the bad join. Delete the dupe area and recreate the surface and join (If you select the correct dupe to delete, then there is no need to re-create the surface). In the back, there was just a little gap from a fragmented edge. I merged the fragment and recreated the surface to get a solid. No need for the intolerant join.

If it is an "interfacing component", then you would help yourself by discovering the originating app/creater and getting a better export format of the part. They would need to look also at any constraining tolerances, which might be making imports in other apps problematic.

[edited to reflect deleting the correct surface from the duplicated area, removes the need to re-create the surface there]

Andrei,
"""""""""OSTexo, Also if you are so pedant, you better look on his model""""""""""

Everything about mould design is Pedant.

"""""Green Cylinder is perefect one, and it stay behinde his cylinder. As you can see his cylinder is wrong""""""""""

You are assuming that it is supposed to be a cylinder? "Wrong" is determined by the application of the design.

""""""""""To avoid that artifacts that his model has, cylinder must be perfect...
This model have 2 mistakes it has artifacts and it is not perfect cylinder. Also it had messy geometry. """""""""""

"artifacts" and "Messy design" are questionable. You can teach yourself this by creating a simple 360 revolve in MoI, and exporting it out as a SAT file, then bringing it back in and inspecting the result. (In a simplistic way)

Messy design? You are referring to the surface edges in the part? These can be of no concern with the surface in a manufacturing application. You may be concerned if you are "rendering" it, or making a poly model out of it for Games. But then, you wouldn't be making parting lines and splits of the original surfaces, for Mould work.

The "artifacts" you see, could be part of a larger structure, with "perfect surface continuity" meeting there. The "export" and "dicing up of the model" may bring this type of surface display into play, but, You cant start just "rebuilding curves and surfaces" at leisure. It will destroy the original intent, surface continuities with regard to the rest of the parts of the mould, which is a "precise model" from the start. It can be a "do not touch" area. The original engineer of the model, would have to address the entire design.

Hello Andrei,

Your first mistake is that you don't have the slightest idea how the model should look for the original posters application. Since you are ignorant of the models application you are making assumptions about how it should look based upon your knowledge of inexact poly modeling, which is about as far away as real world manufacturing is to one of your spaceships. It's obvious that you (still) don't have a grasp about surface continuity or its importance in the manufacturing industry. The funny thing is you don't even need to be in the mold industry to understand why the method of construction he used will help him if he needs to make modifications to the part. If you bothered to read what he posted it would be obvious why he is constructing the model that way even based upon that limited information. He made it clear that certain areas of that part were off limits, what part of that don't you understand? He asked for assistance for a particular area of the model. Do you honestly believe that you somehow managed to find a multitude of "mistakes" with this part for his application based upon your work in fantasy world poly modeling? You do realize if he is not methodical and detail oriented he can easily make a million dollar mistake (actual dollars, not space credits)? By the way, it's not a cylinder and you managed to take wrong measurements. Might want to make sure of the basics before attempting to tell someone else they're doing it wrong.

Looks like you have double standards. Model with continuity - not good, but to have wry cylinder - it is good. Model for molding is pedant - but have artifacts is normal. You do not know what this detail will be and how it fits etc... But you are absolutley know what is good and what is wrong. You are experts in this area and I want to belive you... But some times it looks like you try to protect this model by any means. Anyway I have no all objective information about this subject and do not want to read tea leaves. So I stop discussing. Peace

Andrei,

>>Green Cylinder is perefect one, and it stay behinde his cylinder. As you can see his cylinder is wrong, it is becouse he made that spiral detail constant radius.
To avoid that artifacts that his model has, cylinder must be perfect...
This model have 2 mistakes it has artifacts and it is not perfect cylinder. Also it had messy geometry.
Do not know may be this things are not important for molding <<

I know you are trying to help but you don't understand the design intent. A perfect cylinder will not work here as it will change the geometry required for the article. THIS IS NOT NEGOTIABLE. I appreciate your input but it isn't helpful in this case.

Hello,

With some helix formula help from Michael I am trying to recreate the part using a variety of techniques using MoI only (I'm using Rhino/VSR for curvature, deviation and light lines analysis). There's more than one way to do this but my objective in the exercise is to have a controllable and flexible set of surfaces. The interior details should be an interesting challenge.