Wednesday, October 2, 2013

Iron Cars, Wooden Fingers

I am on the home stretch now for the V150 model.  Adding hinges and lifting eyes and other stuff to it now.  Which is going quickly because there's no real point in doing careful research, or even careful scaling; these items are right at the verges of printability and have to be made large and crude just to pass the software tests.

Oops -- got the periscopes turned around.  Don't worry, it will be fixed before printing.

I simplified the undercarriage a lot, but it still took up the better part of two days.  I left off shocks, power steering cylinders, brake lines, etc., etc.  But then messed around for a while figuring out a way to connect to the wheels so someone could use other wheels if they had them on hand (the wheels have enough thickness in them to cost a whopping $3.98 each to print).

For some reason it took the better part of today to work up the rather simple-looking Rheinmetall Mk20, otherwise known as the Rh202 20mm autocannon.  Several hours of that was looking for better reference material.  The bulk of the rest was not in modeling per se, but trying to get the mesh to agree with two different references which were incomplete, confusing, and contradictory.

For this project I worked in real-world scale.  This is what I have been doing with my Poser stuff of late; it is much simpler to set the workspace to real world scale, including a reference grid, and then re-scale during export.

Carrara's obj export is unscaled (thus useless in Shapeways).  Collada is broken.  So far the only export chain I have working is Wavefront obj from Carrara, re-scale to print size in Hexagon and export as stl (which does have a scale).

But since Hex only displays three significant figures, and Carrara a mere two, I really have no way of knowing if I have more than one piece in scale to each other.  So I'm going to have to do something clever when comes time to send the complete model to the printer.  It might even involve sprues.

A new trick I used this time; I cropped the reference image square, then, using the exact pixel size of an object of known scale (in this case, the hull of the V150), was able to determine the world size of the reference image (8.21 meters, as it happens).  With that, I could set the Carrara working box to 8.21 meters and thus the drawing became exactly world scale.

(Well, almost exactly; an error of 1:100335 somehow snuck in there.  And, yes, I'm using entirely too many digits when my confidence is barely to the first "3.")

At least I'm done with shocks and struts.  On this vehicle, anyhow.  My own needs a little attention now.

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