Recommendation for organic modelling of a glider fuselage.  1-20  21-40

Next
 From:  argo
6074.1 
Hi All

Came (back) to MoI after looking for a modelling program to support my hobby of RC Slope Soaring.

Currently I'm attempting to model a glider fuselage into an organic solid with the intention of 3D printing either the model, or a female mould of the model.

I'm having some challenges with getting the model to be smooth and fluid. If I wanted the model to be like a lathed piece I could easily use Revolve. As the attachments show however, the fuselage has no centre axis as such. I have tried Network but although this worked, it requires building many surfaces and Joining them to make a solid. And the joins are not 'fluid' (organic looking).

My current thinking is to use the 'rails' as a guide and make elliptical cross-sections perpendicular to them, then Loft these. Before I do this though, is there a way just to use the two perpendicular axis ('rails') to make a solid in one or a few passes?

Many thanks,
Brendan.


  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  kevjon
6074.2 
~Kevin~
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.3 In reply to 6074.1 
Hi Brendan,

> Before I do this though, is there a way just to use the two perpendicular axis ('rails') to make
> a solid in one or a few passes?

I'm not sure if this is exactly what you're asking for, but it is possible to loft the long rails you have with each other rather than lofting the vertical stations.

That would be something like join the pieces together so you've got 4 long curves like this:



Then select those 4 long curves in order and run Construct > Loft, and enable the "Closed" option on it to make it a closed loft, that will give a result like this:




If you want to try Network to get more control over the roundness of the shape try doing it just as one big Network all at once rather than doing it only in small separate sections at a time.

- Michael

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  argo
6074.4 In reply to 6074.3 
Wow thanks Michael, I'll give Loft on the rails a go.

@Kevin - thanks for the link! Those tuts of Andrei's are incredible (and I see from the YouTube window - very long!).
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  argo
6074.5 In reply to 6074.4 
Getting the hang of MoI although it took a few goes to get the Lofting right. I was trying to do the Loft with two "horse-shoe" curves, instead of four rail-curves and got fails. Amazing how MoI is able to create the surfaces from the rails!

Question though: the lines on the model below, I can't seem to remove them (MoI ignores delete). The model is showing as a solid and although the lines highlight they will not delete. Not a problem but wondered if there was a reason?


Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.6 In reply to 6074.5 
Hi Brendan, those lines you don't like are just edges of the model, each edge is a spot where there are 2 small surface pieces that are joined together to make a larger structure.

They're the same kind of edges that you'd see on a box where each plane is glued to an adjacent surface piece.

In your case here you probably did a boolean with a cutting curve, and the cutting curve must have been made up of a lot of little segments in it. When the curve extrudes out into a cutting surface you'll get one surface piece for each segment in the original curve.

If you select your cutting curve and use Edit > Separate on it, it will break apart into separate pieces with one piece per segment, that's how you can see the segmentation.

If you drew the cutting curve as one single curve piece instead of out of lots of little small pieces joined together, you would not have all those little edges in there.

You can also use the Rebuild command to reconstruct a segmented curve into a more simple one with only one segment for each smooth piece:
http://moi3d.com/2.0/docs/moi_command_reference10.htm#rebuild

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Andrei Samardac
6074.7 In reply to 6074.5 
If you are talking about those seams, you can not remove them..
If you are talking about seams that apears after trim -
Instead rebuild curve that you use to trim that part. Use command - Rebuild. After that trim it again and there will be no seams..
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  argo
6074.8 In reply to 6074.6 
Hi Michael, Hi Andrei

The seam occurred after I carried out the Loft command. Perhaps I forgot to carry out a Join on that rail? Am I correct in thinking that a Join will make all the curve segments into one curve? Or should I draw a curve (the rail) as Freeform > Control Points?

Sorry these are probably obvious questions. I will read the manual again!
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Andrei Samardac
6074.9 In reply to 6074.8 
I'm not sure what do you mean. Post a screen and mark there you problem. Also if you want you can upload you project it will be easier to solve your problem.

-----------------------------------------
Portfolio: www.samardac.tumblr.com
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  DannyT (DANTAS)
6074.10 In reply to 6074.8 
Hi Brendan,

> Am I correct in thinking that a Join will make all
> the curve segments into one curve? Or should
> I draw a curve (the rail) as Freeform > Control Points?

Yes definitely use Freeform > Control Points where you can to get a smooth curve, one thing about surfaces and modelling from curves is that your surface is going to be as good as your curves so, bad curves equal bad surfaces.

What Michael is assuming and the way most would do is use a curve to Boolean>Diff the shape out as long as your model is a solid, you don't have to use Loft for everything as some might think ;)

Here's a short video showing what I've just explained.



Cheers
~Danny~
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.11 In reply to 6074.8 
Hi Brendan,

> The seam occurred after I carried out the Loft command. Perhaps I forgot to carry out
> a Join on that rail?

Every closed surface has a "seam edge" in it which is a normal part of the surface's structure and can't be deleted. Basically every NURBS surface has an inherent rectangular structure to it like a rubbery sheet of paper. With a closed surface it's like if you took a sheet of paper and rolled it into a tube with 2 opposite sides touching each other. There will be a "seam edge" in that closing spot.

I had thought you were referring to all the small edges running across this area here:




That area of your model looked to me like it came from a boolean cut from a side profile curve, and probably the side profile curve is made up of numerous segments in it. If you wanted to get rid of some of those edges you could run the Rebuild command on your cutting curve before doing the boolean with it.


> Am I correct in thinking that a Join will make all the curve segments into one curve?

It does make it into one curve but the curve is sort of like a group that retains the original segmentation. If you use Edit > Separate on the curve you can see that it breaks apart back into the original segments.

If you want to remove segmentation and fuse adjacent smooth segments into single segments, the Rebuild command can be used to do that.

- Michael
Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  argo
6074.12 In reply to 6074.11 
Thank you all for your informative posts!
Sorry for the delay in replying, part timezone (New Zealand) and part work getting in the way of a hobby :-[

Probably a newby mistake but I didn't stop to think past joined arcs for making the curves, a Freeform curve with control points is surely going to be a lot more 'Bezier' and smooth.

The lines under the fus would certainly be caused by the method I used to create that 'cutout'. What I did was import an airfoil closed curve (PW51 if anyone is interested) and extrude it. The problem is to import, I used a PDF print of a DXF airfoil-plot. This method I imagine created micro-steps in the foil surface which would have transferred to the fus during my Boolean>Merge. By the way, I take it a DXF Import is not currently possible?

So I shall start from scratch (want to change the shape a little anyway :-]), use Freeform curves and build the airfoil-solid by drawing a closed curve over a JPG image of the foil plot and extruding it.

Will also play with the Rebuild command.

Cheers and thanks again.
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6074.13 In reply to 6074.12 
Moi3Beta does do DXF import...

You could also use import points for the airfoil:
http://www.rcsoaring.co.nz/viewtopic.php?f=22&t=138

EDITED: 31 Jul 2013 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6074.14 
How about a 2d version of import points which assumes a z value of zero, (or a constant.) ?


Import the PW51 dxf, if available, or convert dwg to dxf, or ...

or
For the 2d PW51 text file, the commas can be replaced with period in text editor, notpad++, and probably a macro could add the z values of zero.
Or excel could concatenate z values and save to a text file.

-Brian

EDITED: 31 Jul 2013 by BEMFARMER

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  BurrMan
6074.15 In reply to 6074.14 
Or you could just grab the edit frame and drag everything to "flat"...
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.16 In reply to 6074.12 
Hi Brendan, yes like Brian mentions above the v3 beta has DXF import, you can get the v3 beta here: http://moi3d.com/beta.htm

But often times DXF plans may be made up of all line segments and not actual smooth curves, so if that's the case you will want to maybe use the import as a tracing guide or rebuild it or something like that instead of using it directly because you don't really want to have something that's a curved form to be made out of a whole lot of little plane fragments.

- Michael
  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  bemfarmer
6074.17 
Attached is a PW51 text file, from the download link, which may or may not be different from your file.
It is space delimited, modified with decimal points instead of commas, and with "space 0" added manually to each of
the 232 points. The MoI script ImportPointFile (existing revised version), was used to import the points into MoI2, as Control Points, and also as
Points. The Control Points curve looks fairly good. The trailing edge shows one point which is irregularly placed, which may be deliberate?
(The trailing edge comes out badly with through points.) There are fewer points on the top of the cross section, versus the bottom.


EDITED: 9 Aug 2013 by BEMFARMER

Attachments:

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  argo
6074.18 In reply to 6074.17 
Made some good progress thanks to all the suggestions. Got the wing section sorted out by using the foil coordinates to create an image and then building a MoI section over the image using Freeform>Control Points.



Sorry, have more questions though!

I can't seem to shell out the attached solid? I've used Offset>Shell and also Offset>Inset and the function fails to make any changes. Any ideas?



I can carve out a piece using Boolean>Merge with a down-scaled copy of the model-solid, but would like to find out what I'm doing wrong with 'Shell'.



Also the Fillet>Fillet function does not seem to work for the junction of the fin and fuselage base (not that I'm too worried). I selected the seam and and started with a fillet of 0.1mm but no go, also any ideas on this?

Cheers.

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.19 In reply to 6074.18 
Hi Brendan,

> I can't seem to shell out the attached solid? I've used Offset>Shell and also Offset>Inset and the
> function fails to make any changes. Any ideas?

Shell is easily confused by little perturbations in surfaces, part of how it works is by generating offset surfaces and an offset surface tracks along the surface normal of the original surface. If the surface has wrinkles in it or worse yet folds back over on top of itself those get magnified on the offset (think of the offset being like a stick on the surface, any little wiggle at the base of the stick is magnified at the tip of it).

In the back part of your model it looks like there is a self-intersecting or "folding over itself" part in these areas here:




> Also the Fillet>Fillet function does not seem to work for the junction of the fin and fuselage base (not
> that I'm too worried). I selected the seam and and started with a fillet of 0.1mm but no go, also
> any ideas on this?

Fillet also involves generating offset surfaces and then intersecting them with one another, that's part of how it forms the path for the fillets to follow. So anything that hoses out offsets will usually also break filleting in those same areas as well.

- Michael

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged

Previous
Next
 From:  Michael Gibson
6074.20 In reply to 6074.18 
Here's another zoom in to just the one surface:






That looks like the kind of fold over / self-intersection as described here:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1127.4

- Michael

  Reply Reply More Options
Post Options
Reply as PM Reply as PM
Print Print
Mark as unread Mark as unread
Relationship Relationship
IP Logged
 

Reply to All Reply to All

 

 
Show messages:  1-20  21-40