How would you model a pelton wheel?

Next
 From:  sharky0815
4427.1 
Hi all!

I am currently trying to incorporate NURBS modeling in my workflow as it seems to be better suited to most of the stuff I have to model. Still, I can't seem to wrap my head around this... I am trying to model a pelton wheel:

http://www.lingenhoele.at/de/turbinenbau/Peltonlaufrad
http://www.cink-hydro-energy.com/galerie/turbiny/galerie/pelton/pel8_big.jpg
and much more if you do an image search for "pelton wheel"

I made some progress but I am having problems with the sharp crease in the middle and the way the round part blends into the square part where it is fixed to the axle.

If somebody could help me out and give me some tips how to approach this it would be much appreciated.
Thanks!
  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
4427.2 In reply to 4427.1 

EDITED: 15 Aug 2011 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:  Michael Gibson
4427.3 In reply to 4427.1 
Hi sharky, can you please post the 3DM model file of your current progress?

That will make it easier to make some recommendations for you, it's otherwise hard to figure out some of the specific things that you're asking about - like the part about blending near the axle.

For the sharp crease in the middle - it looks like that may be formed by a kind of asymmetrical shape of the basin. Maybe try something like draw an outline like this - note that this outline is not fully symmetrical - one side has been squished to be flat:



I made that curve by drawing one half of it to start with, then mirroring it to get a symmetrical shape, then use Edit > Join to glue it together into a single curve object, then do some control point editing of the one side to squish the points to be flat just in that spot.


Then to surface something like that you can draw in a profile shape that comes downward hanging off of it like this:



Then select that hanging profile and use Construct > Revolve > Rail revolve
(http://moi3d.com/2.0/docs/moi_command_reference7.htm#railrevolve)

Rail revolve is pretty useful for creating rounded type shapes that are not necessarily totally symmetrical because the resolve conforms to the path curve shape instead of just being exactly circular like a regular revolve.

That will then make shape like this:



And then when you mirror along the flat area you will get pieces like this:




Symmetrical shapes won't meet up in that same kind of equal height ridge in the middle.

If you've been having problems with the ridge being too low, that probably means you've been using symmetrical shapes for the basin when it looks like it needs to be somewhat asymmetrical as above, at least that's my guess...

- 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:  Mike K4ICY (MAJIKMIKE)
4427.4 
Hi Sharky,

You could try "adding" and "subtracting" simple shapes together to get your shape.
The process could be done with the more accurate shape that Michael has made above, where the middle crease remains level.
But this is a quick one example...



1) Draw the outside shape of the cup.
2) Use Revolve to create an egg shape.
3) Draw one straight line in a side view and do a Boolean Trim to cut the egg in half.
4) Delete the top egg half and copy the shape to one side.
5) Boolean Union the two halves together. Delete the flat side objects, as in mine it looked like one overlapped the other.
6) Select the outer curves that make up the flat side, Planar them to get a nice flat area and Join that to the double egg half shape.
7) Do the same thing to make a smaller double egg, Union them together.
8) Boolean Trim the smaller double egg from your larger part.
9) Draw that funny cut-out shape, copy it and Boolean Trim them from the new hollowed out shape.
10) Add the rest to make the tool shape. The the rest will be a series of Copy Rotations and etc.

Hoped this helped also.

Mike
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:  bemfarmer
4427.5 In reply to 4427.4 
Is this an art project, to make something that looks like a pelton, or
an engineering project to make the curves match the efficient conversion of energy?
Anyway, an interesting project!
  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
4427.6 In reply to 4427.5 
On 3D content central there is a pelton wheel 3D, And a paddle
There are several formats, solidworks, STEP, STL, etc.
Here is step version of the paddle, imported to MoI.
Looks a bit klunky, not due to MoI. (The Solidworks and STEP versions look klunky also, in other viewers.)

EDITED: 2 Apr 2015 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
4427.7 In reply to 4427.6 


The Pelton Wheel by another person looks a lot better:

EDITED: 2 Apr 2015 by BEMFARMER


Image Attachments:
Size: 45.2 KB, Downloaded: 120 times, Dimensions: 494x411px
  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
 From:  sharky0815
4427.8 
Wow what a helpful community! Thanks for all the hints! I am going to give it another go today and I'll post what I come up with.
  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