Part request (x345, aka 43559, aka 16779)

[Jeroen Ottens]

Hi,

I'm in the process of making building instructions of my latest MOC, but I think this part is not in the LDraw parts lists:

It is the Bionicle Shoulder Armor with part nr x345 (alternative 43559 or 16679). Neither of the three can be found in the LDraw part tracker. Has anyone ever attempted to model this part? Or is someone willing to give it a try?

Jeroen

[Philippe Hurbain]

I do have the part... but it's very tough to model!

[Merlijn Wissink]

Don't you have a 3d scanner or something like that?

Or doesn't it make it that any easier anyway?

[Philippe Hurbain]

Problem is that a 3D scanner provides ugly triangulation that doesn't work nicely with a regular, geometric shape like this one. There are retopology tools that can help, but I master none of them (eg. there is one in Blender, but never got the hang at using this software).

[Merlijn Wissink]

I've seen the model for which instructions this part is needed.
It's a beautiful model and it would be a shame to render it incomplete.

Would someone be able to create at least a mockup version?

[Jeroen Ottens]

On rebrickable they have a digitally rendered picture. Does anybody know how they get those?

[Merlijn Wissink]

I believe (not 100% sure) that's a picture from Lego. Brickset uses these images too. Lego uses these on the replacement parts order page and pick-a-brick pages.

[Philippe Hurbain]

I think this is a scaled-up version of LEGO image: http://cache.lego.com/media/bricks/5/2/4201224.jpg

[Gerald Lasser]

I found it as well and I tried to attack it with the help of the CSG funtcion in LDPE.

I think so far it looks pretty well for a mock-up... The height is not correct now (tinker a bit with the radius and better add a cylinder at the bottom) and the cutouts for the eyes (?) are still missing.


  Mask.PNG (Size: 14.72 KB / Downloads: 11)

Here's the CSG code to get this:

Code:

0 !LPE CSG_QUALITY 48
0 !LPE CSG_EPSILON .0001

0 // Construct the Outer Shell
0 !LPE CSG_ELLIPSOID base  1 0 -20 20 38 0 0 0 44 0 0 0 50
0 !LPE CSG_CYLINDER stretch  1 0 -20 20 38 0 0 0 0 44  0 50 0
0 !LPE CSG_UNION  base stretch base

0 // Cut the outershell
0 // Belly
0 !LPE CSG_CUBOID c1  4 0 6 20 38 0 0 0 26 0 0 0 50
0 // Back
0 !LPE CSG_CUBOID c2  4 0 -40 75 40 0 0 0 26 0 0 0 40

0 !LPE CSG_UNION c1 c2 c1
0 !LPE CSG_DIFFERENCE  base c1 base

0 // Hollow  it out
0 !LPE CSG_ELLIPSOID h_base  2 0 -20 20 36 0 0 0 42 0 0 0 48
0 !LPE CSG_CYLINDER h_stretch  2 0 -20 20 36 0 0 0 0 42  0 48 0
0 !LPE CSG_UNION h_base h_stretch h_cut
0 !LPE CSG_DIFFERENCE  base h_cut base

0 // Second Cut
0 !LPE CSG_CYLINDER  c3 2 -40 -32 24 0 80 0 26 0 0 0 0 26
0 !LPE CSG_CUBOID c4  2 0 -6 24 40 0 0 0 26 0 0 0 26
0 !LPE CSG_CUBOID c5  2 0 -32 50 40 0 0 0 26 0 0 0 26
0 !LPE CSG_UNION c3 c4 c3
0 !LPE CSG_UNION c3 c5 c3

0 // Rounded Corner
0 !LPE CSG_CUBOID c6  2 0 -20 -2 40 0 0 0 5 0 0 0 5
0 !LPE CSG_CYLINDER  c7 2 -40 -25 -7 0 80 0 5 0 0 0 0 5
0 !LPE CSG_UNION c3 c6 c3
0 !LPE CSG_DIFFERENCE c3 c7 c3

0 !LPE CSG_DIFFERENCE  base c3 base

0 !LPE CSG_COMPILE base

[Philippe Hurbain]

Very nice! I played a bit with you CSG script to better understand what happens... Turns out that reducing resolution a lot (I used 16) allows to manipulate the draft much faster.
Then I compiled the result, and... let's say that triangulation is far from perfect. Here is the result after exportation in Meshmixer. The blue lines shows mesh issues (I guess T-junctions).
Apart from that triangulation issue, probably better result would be obtained if the CSG sphere had no distinct poles (something like the LDraw sphe primitive.
   

[Gerald Lasser]

I never compiled it. I do not understand how the algorithm works that it splits the surface into such many quads.

interestingly the interior is quite clean.