Re: Necessary Freight cars (UNCLASSIFIED)


proto48er
 

Andy -

The last project I did drawings for involved brass models made in China. I provided scale drawings (not RR general arrangement drawings that are seldom to scale) with a few measurements on them, and was not sure just exactly what system of measurement the builder would use. Thought he could just measure off the drawing - done 1-1/2 final size and reduced to "O" scale with a stat camera.

To my surprise, the builder wanted a measurement for every little part! I then dimensioned the diddly out of a set of drawings and sent them to the builder by way of the importer. To my surprise, in less than a month, a woman in her 20's in China created excellent 3-D CAD drawings for the car with only a very few minor corrections - on the first try! (At this point, I was really worried about our future as an economy!)

One feature of the CAD drawings was that they were multi-colored. The parts in a single color represented a step in the final assembly of the components of the model. The builder had actually done some good "engineering" of the stepwise construction of the models when the drawings were prepared.

A.T. Kott

--- In STMFC@..., "Andy Harman" <gsgondola@...> wrote:

On Thu, 14 Apr 2011 14:03:14 -0500, cvlk wrote
3D CAD has changed the approach to design of a model. It used to be that
you'd start with overall drawings and work down to the details of the
components (roof, body, trucks, details, etc..). Now it is pretty much the
reverse..... you design details to assemble into a whole.
It would be fascinating to see the process of how a 3D CAD drawing of the prototype is
turned into the actual tooling specs for the model. I've been reviewing some 3D
drawings for a forthcoming product, and I'm really just seeing a forest view, nothing
about how the individual parts will be defined, how they will all fit together, etc. I
suppose in a lot of cases that part is entirely done by engineers in China. But I'm
having a lot of trouble communicating the changes just in what I'm seeing - and I'm
working through a 3rd (or 4th?) party so I'm not even sure where the lines are breaking
down, or how to word my suggestions and corrections so that the guy on the final
receiving end knows what I'm talking about, and I don't know if that person speaks
English, Japanese, German, or Chinese. I'm kind of reduced to sending back a clip of
the drawing and a prototype photo of the same view and saying sheesh, look a it, yer not
even in the ball park! I'm sure whatever mistakes end up in the finished product will
be blamed on me, but I'm so far removed from the process that I'm not sure I'm helping
much. The last round, about 3 of the 20 things had been corrected, none of them
adequately, the other 17 were ignored, and two new errors injected. All of this just to
get to a 3D representation of the whole, which then will have to be picked apart into
assemblies and parts and tooled from there. If the person doing this even took vague
interpolated measurements from the prototype photos I supplied, he would have nailed it
almost completely the first time around, but at this stage, I have to wonder just what
it is they're looking at.

Andy

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