Understanding the Minimum Wall/Wire Criteria

Hi,

I am after a little help understanding your design guidelines for FUD.

The Rules Are

Min Wall Supported: 0.5mm (Frosted Detail) • 0.3mm (Frosted Ultra Detail)
Min Wall Free: 0.6mm
Min Wire Supported: 0.6mm
Min Wire Free: 0.8mm (if not bearing weight) | 1.0mm (if bearing weight, like a sprue)
And the guide says not to make walls that a 0.3 thick bigger than 30cm by 30cm

So a rectangular post, is it a wall or a wire. If it is a wall and it is 0.3 in one direction and 0.6 in the other, does that mean the 0.6 wall supports the 0.3 wall.
Or if that is a wire, which side need to be 0.6 or 0.8? Or is it both?

Thanks,

James

In truth, "wire" is a word used in an attempt to define "long thin floppy piece that won't stand the stress of cleaning". The exact cross-section of it does not matter. Square, cylindrical, or even C shaped - all of them can be determined a "wire".

There has been a good bit of discussion in other threads about "wires". It's unfortunate at this time that there is 1) no "scientific" definition, and 2) the definition is up to the human checking the item - often the definition is applied AFTER something has broken during cleaning. Since the definition is "variable", I can't directly give you a hard "scientific" answer. But:

"Support" generally means something that attaches to the piece at a perpendicular or near-perpendicular angle.

For a piece that is 0.3 by 0.6 by 10mm and anchored at both ends - that's going to break. It's a wire. Both dimensions need to be over 0.6

If it were 0.3 by 0.9 (or more), then it'd be a wall.

Hi, that's a big help,



I have now made the depth of the ladder just over 0.9, the width is 0.3 at the thinnest but 0.4 at the thicker areas. It used to be 0.68 deep. Hopefully it is now a wall configuration. Do you think it will print?

Thanks,

-James

It worked, making the ladder 0.9 deep did make it a wall and my model has gone to print. (the whole model is a lot bigger than 1 ladder).

Thanks for the help.

James

I just had a similar issue with a mask model. The thickness is about 0.8mm to ensure it meets the minimum wall requirement. The problem is, one measurement hit 0.79mm and it was rejected as a wire, even though in the other axis it is 5-6mm. This works out to 5x the cross sectional area of the minimum unsupported wire. In addition, it actually is supported, just not within 10mm.

I've attached the measurement screenshot. This model has been successfully printed about 25 times.

Lost another sale.

I should add that this is printed in White Nylon.

Here is the model: Adventurer Mask

I've re-uploaded it to make it for sale again, because dang it...there's nothing wrong with it.

I wonder what will be the consequences if the model prints successfully - will you amend your internal rules to have it pass in the future, or will any subsequent model that re-uses this detail face initial rejection because of it? To me that ladder looks sufficiently generic to fit many industrial contexts where the height does not mandate a caged safety ladder - railcars, big scrap containers, powerplant boilers etc.

Requesting clarification from service would probably have been a better choice - the re-upload now makes this definitely a "new" model that cannot rely on any previous printing history. It could be that most of the 25 successful prints required a reprint, or it could reveal a flaw in their database system (if there were recent prints of this model that did not count towards its printability score).

My apologies, I did not want to force your hand. In retrospect I should have made my observations in a PM.

Stands to reason that Märklin et al. use individual styrofoam containers around their models. Probably somebody needs to invent
some light, cheap, eco-friendly, water-soluble gel that can be poured around models for shipping. :confused

Mitchell,
Thanks for taking the time to explain. I spoke to CS and they did say they consider it a wire. It is a little odd since it is only an aspect ratio difference and has far more material in cross-section than a 1mm wire, but whatever the perception is I can work around it as long as it is self-consistent.

It might be something to add to the design guidelines, that a free floating wall, a ribbon-like structure at any width, will be considered a wire. Does the definition of a wall require some structure (a "floor") coming away from it perpendicularly perhaps? That should be in the guidelines, then. In the mean-time, I think I have a solution that doesn't harm the aesthetics and still passes inspection without the 30% cost increase of a solid 1mm plus margin. How about if I have a 1.1mm circular section at each edge of the wall, and the wall is 0.8mm thick? That would mean the edges meet the free wire criterion, and the span, whether considered a wall or supported wire, still meets the minimum.

In cross-section this would be a slight barbell shape. It's a good solution for my issue, but I know not everyone's designs will look right with a ridge on the edge. I will attempt another order myself to see if it passes muster.

As a note to others about why the design printed so many times before at 0.8mm, while it has been purchased individually by customer from Shapeways, I normally order packs of 5 and 10, and they were arranged in a very close "onion-skin" concentric pattern, and held together with rings. This made them very easy to produce, and I still order them this way for inventory. They would arrive still lightly stuck together, and I kept them that way until they were purchased by the customer to avoid having them deform in transport. Unfortunately I can't have them produced that way for individual direct sale from Shapeways.