3D Printers for buildings

There is a company in the UK making loco bodies using such a system, the scale isn't of interest to me but the feedback so far has been good.

They are producing early (for the UK anyway) diesels on a high quality chassis and the photos looked good - Sorry I cannot remember or find the URL.

Make friends in the hobby. Keith Visit Garratt photos for the big steam lovers.

As others have said, "interesting idea, but..."

I spend a fair amount of time around rapid prototypes.

The starch machines such as you mentioned in your note make nice, cheap, quick parts useful for show and tell. They build parts out of layers of starch. The final part has a waxy coating on it that probably would not take paint very well. They are also about the least dimensionally stable of the rapid prototype technologies (humidity causes them to warp a little). We have two of the machines in my building. Their strong points are quick and cheap (relatively). The machine lays down a layer of powder, hardens the portion of the layer that will be the part and then repeats the process. Downside is that the part is coarse, but when you are dealing with large parts it does not matter.

Someone else alluded to sterio lithography. You focus a laser in a tank of some polymer goop and it causes the stuff to harden. Repeat a few zillion times and you have a part. This stuff is hard, fairly durable. dimensionally stable, and expensive (something like $40-50k to fill the 2'x2'x2' tank with goop, your part costs whatever portion of that volume you use + fees). Parts are not as coarse as the starch parts, but still have a definite staircase effect.

There are other methods that lay down a string of molten plastic, or use a laser to locally sinter metal powder, etc. All have their benefits, disadvantages, costs.

I'll stick to buying premade plastic sheet and details.

TechCAD Design Limited, P.O. Box 100, Kirkcaldy. Fife. KY2 5W, Scotland

Hope this helps, Alex. W. Stirrat

As far as I know, the technology with the highest resolution is by Sanders. It is effectively an X-Y wax jet printer. After each pass, a very wide milling hob flattens out the last layer very accurately. They claim resolutions of .0002" X & Y and .000125" in the Z axis:

Click on "RTM" on the left side. Last I knew, the models were very brittle and fragile and the machines were about $35k. I think they would make excellent masters for resin casting.

Oh, and I recommend SolidWorks for making the .stl files.

Bill MacIndoe