The Ship Model Forum

DrPR wrote:Rusty,

You can get STLs from DesignCAD via the Accutrans ($25) translator program. You putput V12 DXF files from DesignCAD and Accutrans imports them and converts to STL. It does an amazing job!

That's good to know. I wasn't looking forward to learning a new 3D CAD program. As inexperienced as I am with 3D, I have found learning two CAD programs to be almost impossible due to my getting the commands constantly mixed up. I don't know if it's me being CAD dumb or what, but I gave up on Auto-Cad for that very reason.

However, be warned that STL is extremely unforgiving. You can have NO gaps in the grids in your solids, and DesignCAD will allow you to create gaps if you are not careful. I speak from experience! There are programs that "heal" gaps in STL files. Most 3D print shops have software that will do this, at an additional cost to the customer.

Once again, it would be so much better if DesignCad was designed to import and create STL files. They could design a correction program compatible with DC to repair mistakes.

The main problem with 3D printers is resolution. Even the very best will generate "jaggies" in the surface. The process builds up layers one step at a time. This step size sets the resolution for the jaggies. Even with extremely fine 0.0001" steps, if you are printing a surface that is slightly off horizontal the jaggies will be noticeable. Some processes coat the 3D print object with a liquid that fills in the jaggies to some extent, but even these aren't perfect. Like Fritz said, you will have to do some cleanup to smooth the surfaces.

This is a revelation to me. When I pull up these various web sites, they show the amazing things "supposedly" their printers have made for those who use them. I must be mistaken. The results on the websites show beautifully smooth and complex subjects.

Another problem is durability. Most 3D print products are extremely fragile and don't hold up well in handling - a real problem if you have to do a lot of cleanup. There are rugged 3D print processes - fused scintered stainless steel, for example, but these are usually lower resolution, and also much harder to clean up.

The research I have done on several printers shows that they now can make prototypes from ABS plastic which they say is very durable.

A third problem is warping. It takes time for some of the resins to cure, and if the design does not include supports a long, thin object may sag while curing. This will create a badly distorted part. I have a friend who created a 1:48 scale quad 40mm Bofors mount for an Iowa class model. He made the mistake of sending the entire assembly as a single file. The gun barrels came out bent, the shield was badly warped and had serious jaggies, and some of the fine detail parts broke under their own weight. It was a $2200 mess. You need to be very careful how the parts are oriented - longest dimension horizontal, but try to avoid orienting parts so that gentle curves or slightly angled surfaces are horizontal (more jaggies). It is necessary to add support sprues to hold up long thin pieces (or they will sag under their own weight as they are being printed). The print shop usually adds these sprues for printing and removes them after the object has cured.

I thought as much. I suspected i would need to design the parts with supports much like the casting gates I add to the parts I cast.

High resolution 3D printers are very expensive. Printers that can make larger parts are more expensive. Before buying a printer you should try making a few parts through a 3D print shop. If they can't get acceptable results you will certainly be wasting a lot of money if you buy a 3D printer.

Try it before you buy it!

Good advice.

Phil

Sean Hert wrote:Sadly, Formlabs is being sued by 3DS for patent violations- I don't know if we'll actually ever see their $3,000 Form 1.