Posted on

3D Printing Tips for Shapeways’ Stainless Steel

Shapeways recently did a blog post on “How to Deal With Rejection“. I’ve been using Shapeways for a while now but many of my new designs are still rejected at first! So this was something I could definitely relate to. I wanted to share some 3D printing tips I’ve learned.

This is a design I had to tweak several time to make it 3D printable
This is a design I had to tweak several time to make it 3D printable

The material I use most often is their stainless steel material. It is a great material because it is relatively inexpensive, but is available with nice finishes like gold-plating. There are challenges in designing with this material, though.

Their material page says designs must conform to the “Sandcastle Rule”. This means that weak, unsupported features may “crumble” during their manufacturing process. Their page also says the minimum wall thickness for this material is 3mm. Many of my designs are closer to 1mm wall thickness, and yet they still come out OK. What gives? I have worked with Shapeways’ excellent customer service and gotten some feedback on this. I have been told that for small objects (like jewelry) you can go down as low as 0.7mm wall thickness. How small is a “small” object? Well, that is kind of a judgment call by the engineers at Shapeways. 3D printing is still somewhat of an art.

I’ve also been told that “details” can go down to 0.5mm with this material. What is the difference between a “wall” and a “detail”? They use a rule of thumb that a feature is considered a “wall” if it is more than twice as tall as it is thick. What does this mean for designing? If you have a feature that is less than 0.7mm thick, then it must be shorter or it may be at risk for crumbling. I generally will make features less than 0.7mm wide only about 0.5mm or 0.6mm tall. That being said, you don’t want to go much less than 0.5mm tall, because then you are pushing the limits of resolution. This is especially true if you are getting the gold or bronze plating. The plating is thin, but it can cover up or blur tiny details.

Here are some tips in designing for Shapeways’ stainless steel material:

  1. Don’t get discouraged if a design is rejected. From my experience, Shapeways views challenging designs as an opportunity for them to stretch what is possible, so they are very willing to help you figure it out.
  2. Check your features with NetFabb. This free tool will tell you wall thicknesses and heights of features, and let you check problem areas closer.
  3. Make your walls thick up front. This is not always an option, but it is the most important thing to keep in mind when designing.
  4. Make details shorter. A design could be rejected because your “details” were actually too tall and were considered “walls”.
  5. Add support. You can only use the smaller 0.7mm wall thickness if it has enough support. Otherwise you will have to be closer to the 3mm limit.
  6. Go with the plain stainless steel if detail is more important than finish. The gold and bronze plating are thin but they can cover up tiny details. The trade off is the finish is not as nice.
  7. Go with the matte finish if your design has many nooks and crannies. Their polishing process can’t get into all the corners, and honestly, I think the matte finish looks great. The polished finish looks great for flat, even surfaces.
  8. Consider using a different material. If all else fails, the plastics and their silver and brass materials do not have to meet the “Sandcastle Rule”, and can handle thin walls and details better.

I hope this helps, and good luck!