I may be the only one—and I do feel really stupid—but I'm simply not privy to the technology involved here that allows reproducing/scaling/sculpting with such accuracy! What is "printing"?
:wacko
:confused
Don't feel stupid, you just don't know. And thanks for the question.
A lot of people have their own ideas about using this technology. They think it's point and click, everything just appears by magic. It's no where near that. To use these tools takes training, experience, and endless trial and error.
Before I can do anything I have to start with a model, namely a model created in the computer. Those start out as drawings in the computer.
This is what started the whole thing for me(please forgive the image quality), These drawings were created by Alan Sinclair(wizardofflight) in Autocad. They were his take on the 11' Enterprise. In my opinion they are the best that is commonly available(there are better drawings out there, I've never seen them, they are something that takes contacts to get. But his are real close, his parts almost match the JK 66"E & the MR E, I have both models and made comparisons to these drawings, I can't say any of these are 100% accurate. Nor am I making any claims it's going to be truly accurate, I'm just going by what resources I had access to. So no ultimate claims here).
I then take/modify these drawings to create a 3d model.
But that's just the beginning of this process. Models such as this are useless in this state. It has to be broken down and simplified for construction. When I do this process I don't bother with formal drawings, that would be a waste of my time(the only time I do it is with outside contractors).
The next step is to figure out what will be made with what process, and determine the internal structure. This process can take ages, and endless revisions. I can't tell you how many times I've recreated the same parts. It's like building a house, there will always be surprises along the way.
Once I have an idea of what I want to do, then the fun begins.
Take for instance the 2nd hull.
To get to this stage takes a lot of effort, it's nothing like how the original was made. The original was a made of balsa planks and turned to shape on a lathe, the original was a one off, the guys that made it were on a budget and a deadline. Nobody cared how they did it, just that it was done on time and below budget.
Where is start is with a profile.
This shows the side view of the 2nd hull. Since the hull is circular this makes things easy. Well easier than it could be. From this drawing I layout pieces that make the bulk of the part. I cut out each piece and laminate them to make a general shape of the part.
I then make a rough cut of the part below the final surface.
Here is the final part in RinoCam.
This is a wire frame model, this is what I use to create tool paths(it tells the machine how to move to create the shape of the part). That looks like this...
The software creates a path dividing the part into a series of profiles, in this case they are spaced in .01" increments. This is(in essence) the same as the traditional method of setting profiles at regular intervals, and filling in between them, then fill & sand to shape. Using machines make that process much more efficient and accurate to the shape desired. BUT, it makes mistakes, and it's leaves a surface that requires finishing(you can't just put the part in rubber). If this isn't modeling I don't know what is, because I still have to do all of the same stuff I would with a resin model. I still use Dremels and X-acto knives on these parts, plus the sanding seems endless.
This is the part coated with bondo and being milled to shape(this can take several tries, to get right). The final cut for this part took over 30 hours. But the machine doesn't need to rest, eat or take bathroom breaks.
3D Printing is very similar to milling.
This is my printer(the box to the right is the depowdering station), it is the same as a HP inkjet with a 3rd dimension.
Only it eats print heads at a much faster rate. It uses a powder as a base and prints a section of the part desired with a binder(it makes the powder stick together). Then it drops (.004") spreads another layer of powder and repeats the process. The software screen looks like this...
This software turns a 3d part into a series of layers. Or sections if you like. The section being printed is displayed on the right. The software controls the printer, this is one of the easiest pieces of software I have ever used. But then what's doing isn't that complex. The milling software takes a lot more effort to get right. But then the printer can literally print any shape(withing the realms of physics).
Here is what the work area of my printer looks like...
It doesn't have a very big capacity. So I have to make parts fit it's work envelope(8"x10"x8").
The fun is getting parts out of the machine. They are buried in the powder(and it gets a little messy).
This is the forward part of the Botany Bay(in the printer), scaled to my 66" Enterprise.
This same model was scaled down to 350 scale and offered from Sovereign Replicas. The patterns were later sold and the same model is offered from Fantastic Plastic. These parts are in the depowder station, where any remaining powder in the parts is cleaned out. I use brushes and an airbrush, the depowder station is connected to a vacuum to catch and collect any airborne powder.
This is the 350 scale model, I'm showing these images to give you guys an idea of how this stuff works. I could literally make this model any scale at will. Saying that makes it sound easy, in some ways it is. But you still have to use modeling techniques after this stage. The surfaces show the striation of the building process, and have a very grainy texture. Plus they are not very strong. The parts are very porous I use CA to soak into the surface to strengthen the part. Then it's back to traditional modeling again.
I hope this was informative, I'm sure I missed something, so please ask questions.