Is this possible in glass?

My Mother's birthday is coming up at the end of November, and I've designed a pendant that I think would look good in glass... but is it possible?

The model is here and the description gives the dimensions.

In the design rules for glass, it mentions a 3mm cross section... is that 3mm^2 (i.e. 1.5 x 2mm) or a minimum side length?

Any and all opinions welcome.

3mm is the minimum wall thickness. That means every part of your object must be at least 3mm thick.

This design would print in glass as is. The question is, will the part survive in the real world? Is this piece intended as a shelf sitter or a piece of wearable art? The nature of this moebius design will produce a part the can flex to a considerable degree. Remarkably, the glass media can absorb this kind of stress...................... up to a point. Once this upper limit is reached it will not deform like plastic or metal it will simply shatter like, ummmmmm, glass. My advice is to simplify the design into 2 not 3 bands and thicken the surface by a factor of .5x -1x. Chunk it up, it would still look great and durability will increase. If it's intended for display only then let it rip.

-G

Thanks for that -G... I just ordered it (literally, before I read your response) so we'll see what happens. Chances are my Mum will tuck it away in one of her cabinets alongside her Caithness paperweights and other glass art.

Very curious to see how this turns out--I've found my glass prints a little on the brittle side, though very carefully packed. You'll have to post in "it arrived" when it does .

sincerely,
Jeff

"I've found my glass prints a little on the brittle side"

Well................... it's GLASS! Like all brittle materials, glass has no yield point, meaning it cannot be permanently deformed before failure occurs. Most metals and plastics are ductile and will change shape (yield) at stress points before breaking. For example: if you bend a copper wire back an forth and then closely examine the bend zone you will notice that the material has changed shape ( necked in). Although it may seem counter intuitive, glass is in fact resilient. Meaning that it will flex without changing shape. Because glass can not yield, it will continue to flex right up to that magic moment when it fractures.

It is vital to understand these properties when designing parts, especially those to be made from a brittle material like glass . By avoiding stress risers, meaning design features that concentrate stress, it is possible to maximize the overall strength of a part. Smooth sectional transitions and the liberal application of blends & fillets will greatly improve the strength of your designs.

-G

Oh well, the glass pendant turns out not to be printable because it is too thin... back to the drawing board.

To clarify--I meant "brittle as far as glass goes". There are objects and designs that would work fine in blown or kiln-cast glass but in 3D printed glass production where vitrification and annealing are not happening the same way they do with these other processes, you end up with designs much more brittle than you might expect and that was my experience with my glass prints. It's still very cool, but to think that designing for 3D printed glass is the same as designing for any other glass would be a mistake.

sincerely,
Jeff Coleman

Hi all,
I was part of the team that developed the 3dgp process offered by SW. And in some ways Jeff is correct in mentioning that the printed glass is not the same as blown or kiln cast glass. The end product is very close to results produced by the pate de verre process which uses glass powders, mixed with binders then packed into plaster molds and fused into a solid mass in a kiln. The result is a translucent glass mass. The translucency is caused by minute air bubbles that remain trapped during the fusing/sintering process. This entrained air /gas also occurs in the 3d prints. So far we have found no way to totally eliminate this factor. And yes, the presence of the bubbles does produce a somewhat weaker mass than fully melted (fined out) blown or cast glass. However, the thermal cycle used on all SW glass prints does include a full annealing step (stress relieving).

That said, I believe many, if not most, failures and disappointments in 3dp, particularly in glass are due to bad geometries within the design of the part. I can not tell you how many glass finger rings we have managed to produce with shank diameters of .5-1mm. Or chunky pendants with whisker thin chain loops pasted onto the surface. Does anyone really expect these to survive real use? Objects with sharp notches, abrupt intersections and radical sectional changes ( in ANY material) will always be weaker when compared to objects designed with flowing curves, smooth transitions and liberal use of filleting.

I know it can be a pain in the butt to add fillets and blends to every intersection of a design. But, it can make all the difference in the world when it comes to creating a useful part or something that just can't wait to return to it's powdered state.

-G