@ ppj: L'interface française fait gagner 11 pixels de large sur l'espace de travail par rapport à l'anglaise! :D

French interface saves 11 pixels wide workspace compared to the English! :D
:)

Hi Steve,

> but I still say that attempting such miter based on one
> intersecting bisector will not work well.

I don't quite follow - it seems to be pretty clear that sweeping between angled profile curves does work better on the situation that was originally posted.

That's the one that was attached to the first post of this thread here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3575.1

That's actually a more simple situation than the one with the long curves.

I'd say that it is more important to generate a tolerable result (without any badly mangled or self-intersecting geometry) for the original case than focusing on generating a more uniform thickness result for the 2nd case which is more of an exaggerated test case.


I've attached the result of using this technique on the original posted model, it creates a result that has no self-intersecting areas, so it can be used for things like a boolean with the main hull.

The technique that you are saying is better makes for badly formed self-intersecting geometry here, which would likely cause boolean calculations to fail. I would have a hard time convincing people that is a better result than the attached version.

- Michael

Hi Michael,

>>I don't quite follow<<

That is obvious.

You are still working from a single bisector, although you can get a result of a solid, that does not make it correct. It may be OK for hobby stuff, but the model you posted, it would be rejected in my work, as there is error of between 0.025/0.05 in the position of the angled profile (I only bothered to check the first.)

As you now have it in your head, due to the bad geometry posted from the output of NX by another member, and you appear to believe that calculations can only be made from a single bisector, I will not waste my/your time further.


- Steve

Hi Steve, I'm sorry but you're not making very much sense here...


> It may be OK for hobby stuff,

Wow, you mean anybody else other than what you work on must be doing "hobby stuff" ? That's a quite patronizing attitude.

There are all kinds of people producing professional work that would like to simply get a good looking result for that case. Just because they want something quickly that looks good does not mean that they are doing "hobby stuff".


> but the model you posted, it would be rejected in my
> work, as there is error of between 0.025/0.05 in the
> position of the angled profile (I only bothered to check
> the first.)

So would the result posted from NX with the self intersecting geometry be accepted as a proper result for your work instead?

Or is there no CAD program that can automatically generate a result for that which you would consider acceptable? If so then MoI is no worse off than any other CAD program since none of them can do what you seem to want there.

You will probably need to do some custom modeling instead of using an automated tool to get what you consider to be correct.


> As you now have it in your head, due to the bad geometry
> posted from the output of NX by another member, and you
> appear to believe that calculations can only be made from a
> single bisector, I will not waste my/your time further.

Well, it's not just NX in particular, but rather that whole technique of morphing just the end control points of the sweep to the miter that is prone to that kind of self-overlapping error.

It's something that would be quite difficult to avoid with an automated algorithm without spending a really long time with heurstics or almost artificial intelligence type of analysis of the spacing and shaping, etc...


It's really curious that you say the method I used is not good, yet here is a simple case where it produces a result that the original poster would have most likely considered to be a great result...


- Michael

Great model ppj, it's cool to see an other modo user enjoying MoI booleans power :)

Hello Michael,

>>Wow, you mean anybody else other than what you work on must be doing "hobby stuff" ? That's a quite patronizing attitude.<<

I did not mention anyone else, please show me where I did!
I think overall that MoI is no good for my work, MoI output is not accurate enough and when the models are taken into the other packages I use there are many errors, yes, the errors are (usually) within the tolerance of MoI, but not for being acceptable for my work (I do not make the rules of what is and what is not acceptable). That is not patronizing, just a fact.

I find it amusing that you jump between examples of this mitering and then just post an acceptable result from the first posted by the OP

Why did you post the example (http://moi3d.com/forum/index.php?webtag=MOI&msg=3575.4) I was replying to (and I though we where discussing), and then not post an example showing a good result with you method?

The first rail/profile posted can easily be done with the various CAD systems I use, even Rhino can give a good\usable result with 5 mouse clicks.

Anyway, have fun.

- Steve

Time to close this thread I suggest. It's just going around in circles.

Nigel / 3DKiwi

Hi Steve,

> I did not mention anyone else, please show me where I did!

You said that the result generated "may be OK for hobby stuff" - however, the result that I posted would be ok for a lot of different purposes, like someone more focused on just quickly getting a model for rendering, or for some design like a piece of jewelry that does not have to be exactly tubular to a tight tolerance, or a ton of different things.

Your statement is basically placing all these other kinds of people's work as just "hobby stuff", even though what they are producing is actually a part of their real job, it's just different from your job.


Of course, I can certainly understand if MoI is not the right tool for your job, if you have specialized requirements then use specialized tools.



> Why did you post the example
> (http://moi3d.com/forum/index.php?webtag=MOI&msg=3575.4)
> I was replying to (and I though we where discussing), and then
> not post an example showing a good result with you method?

Well, there were various different parts to the discussion earlier in this thread, that particular one I was giving an example of how you can't actually have a completely even thickness tube that has a common miter-like joint between 2 pieces that are curving around all over in 3D.


> The first rail/profile posted can easily be done with the various
> CAD systems I use, even Rhino can give a good\usable result
> with 5 mouse clicks.

One that matches your definition of within tolerance and not the "oh-so-terrible" result from sweeping between angled profiles?

If so then by all means show it.

If you do a regular 1-rail sweep in Rhino it will produce this result:



If you enable the "Untrimmed miters" option, then it will produce this result:




Note from the slanted isoparms there, that this is a sweep between angled profile curves, which is the kind of result that you had earlier said was totally unacceptable.

Is it suddenly acceptable now?

- Michael

Hi Steve,

> I think overall that MoI is no good for my work,
> MoI output is not accurate enough and when the
> models are taken into the other packages I use there are many errors,

Just curious, what other packages do you use ?

I use NX6 at work and I have done various models in MoI with quite good results when importing into NX, we work to an accuracy of 0.005mm(0.0002") and 99% of the time the models from MoI pass the tolerance check amongst the other surface checks which do well most of the time, if a surface does fail it doesn't take much to fix.

I don't know how complex the models are that you are bringing in from MoI to your other packages but this model I made 2 years ago in V1 passed the tolerance check at 0.005mm, there were a couple tiny objects and a couple of self intersections which where caused by the fillets which took me no more than 5 minutes to fix.

I believe working below an accuracy of 0.005mm is impractical in the real world unless you're into nanotechnology which is an entirely different world altogether.

If your getting a lot of errors with your models maybe try another modeling technique, like, I found I get better results if I use basic curves and arcs where possible instead of a freeform curve where you don't know what degree it is or how many segments it has.

I actually purchased MoI for home use and truthfully, I didn't expect a super accurate solid modeler but in the end it has preformed better than my expectations, I can even say it does better in a lot of areas than some mainstream CAD modelers that cost 10 to 20 times more.

Cheers