Friday, September 27, 2013

Details, Details

The V150 hull is closed up and watertight now, and is probably printable.  I'm doing most of the detail work before I send the test mesh in, though.

Yesterday was turning it from a solid model to a hollow model.  And that was a lot more painful than I had expected. 

First, all of Carrara's automated tools bollixed on the mesh.  So I had to do it manually, one plane at a time.

Then I checked dimensions.  And the thickness I'd eyeballed was way under.  The minimum printable wall thickness is 0.7mm, and I was aiming for a margin with 1.0mm (or a little more).  That's almost 6 centimeters in the scale world.  Let's put it this way; the bottom plate armor of the real thing is less than 1/4 the thickness I have to make it in order for it to work in the 3d printer.

A lot of this would have been much faster if I hadn't made the doors and vision blocks and hatches as framed "holes" in the mesh.  For the battlemat version, none of the hatches need to open and in any case it would have been faster to do the extrusion and thickness if I had the simpler slab sides.  Lesson for next time.

So all that ate up a day.  Today was starting in on detailing.  Although the print will support details as fine as 0.2mm (a bit over a centimeter on the real vehicle), I've enough experience both with how smaller details can collapse or fill in, and how much I have to exaggerate details in order for them to be properly visible in scale.  On the real vehicle, for instance, the outside of the vision blocks is mostly a weld line, with a small retainer plate holding a gasket.

In the model, I am extruding the whole edge a couple of centimeters.  And, yes...since the shapes are already in the model, I'm making a smoother mesh and less material waste by extruding many details instead of adding them on.  The only exception so far is the exhaust shroud.

I've also been tesselating the various curves.  Originally, I intended to subdivide the entire model.  But Carrara's tools get a little funky around some shapes, and I was having to dial up the Sub-D to ridiculous levels in order to smooth out the puckers.  Plus the mesh was wrapping around itself in places and might end up unprintable as a result.  Oh, and Carrara crashed a lot.  It doesn't seem to like Sub-D on a model with multiple surfaces.

To do all these small details I'm jumping around between nicely drawn plans of a V150S, a walk-around book of the V100, and a plastic model of a late-issue foreign-export V150.  Many details don't match, of course.  Some are just plain difficult to find reference on.  I have a fairly good sense of what should be on a Morrow Project era V150, and I'm able to chart my way around some of the things present on Thai and Philippines reference photographs that shouldn't be on this version.

But with all that, plus the issues of having to build a mesh that can be 3d printed, means accuracy is pretty much gone by the roadside now.  I'm eyeballing everything at this point.  At least the basic hull shape is about the right proportions and angles.  And I've got the locations and more-or-less sizes of the various hatches off of references.  But the details and curves and thicknesses are all eyeball and trackball now.

A few more days.  I should be able to test the hull with the Shapeways software tonight, but I still have undercarriage, wheel hubs, turret detailing, and random bits like filler caps and jerry cans to do before the thing is complete.

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