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# Understanding the Minimum Wall/Wire Criteria

Understanding the Minimum Wall/Wire Criteria [message #76763] Tue, 15 October 2013 12:23 UTC

Hi,

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

The Rules Are

Min Wall Supported: 0.5mm (Frosted Detail) â€¢ 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
Re: Understanding the Minimum Wall/Wire Criteria [message #76778 is a reply to message #76763 ] Tue, 15 October 2013 14:01 UTC
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.

Patience, Persistance, Politeness - the 3Ps will help us get us to Perfect Printed Products
Re: Understanding the Minimum Wall/Wire Criteria [message #76780 is a reply to message #76778 ] Tue, 15 October 2013 14:24 UTC
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

Re: Understanding the Minimum Wall/Wire Criteria [message #76925 is a reply to message #76780 ] Thu, 17 October 2013 13:15 UTC
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
Re: Understanding the Minimum Wall/Wire Criteria [message #76995 is a reply to message #76925 ] Fri, 18 October 2013 12:33 UTC
Hi James,

I have had a long discussion with out production team who disagrees that this is a wall.

If everything goes alright we will know on Monday if the ladder survived or not.

Best,
Mitchell

Customer Service Coordinator
Shapeways
Re: Understanding the Minimum Wall/Wire Criteria [message #77000 is a reply to message #76763 ] Fri, 18 October 2013 15:26 UTC
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.

Re: Understanding the Minimum Wall/Wire Criteria [message #77003 is a reply to message #77000 ] Fri, 18 October 2013 15:33 UTC
I should add that this is printed in White Nylon.

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

Re: Understanding the Minimum Wall/Wire Criteria [message #77065 is a reply to message #76995 ] Sat, 19 October 2013 10:41 UTC
 MitchellJetten wrote on Fri, 18 October 2013 12:33 However as we still want to help you I have asked them to test the ladder anyway. If everything goes alright we will know on Monday if the ladder survived or not.

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.
Re: Understanding the Minimum Wall/Wire Criteria [message #77066 is a reply to message #77003 ] Sat, 19 October 2013 10:52 UTC
 ThreeForm wrote on Fri, 18 October 2013 15:33 I've re-uploaded it to make it for sale again, because dang it...there's nothing wrong with it.

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).
Re: Understanding the Minimum Wall/Wire Criteria [message #77117 is a reply to message #77000 ] Sun, 20 October 2013 10:31 UTC
 ThreeForm wrote on Fri, 18 October 2013 15:26 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.

Hi there,

Unfortunately your model requires to be 1mm as this part is actually a long wire, this is the rejection reason of your model:

Note: on your computer there is no gravity, when we print a model with wires of 0.8mm it will most likely look like spaghetti.

Cheers,
Mitchell

Customer Service Coordinator
Shapeways
Re: Understanding the Minimum Wall/Wire Criteria [message #77118 is a reply to message #77065 ] Sun, 20 October 2013 10:37 UTC
mkroeker wrote on Sat, 19 October 2013 10:41

 MitchellJetten wrote on Fri, 18 October 2013 12:33 However as we still want to help you I have asked them to test the ladder anyway. If everything goes alright we will know on Monday if the ladder survived or not.

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.

It's going to take me some time to have a correct answer for you.
Let me get back to you as soon as we know if it works or not.

Reason for this is that I really had a difficult time convincing the production team to print the model, it even included some managers
The biggest issue here is: the ladder is reallllyyyyy fragile, printing won't be a problem at all.

It's the post process, cleaning the model and after that trying to ship the model.
As this customer added 18 different models in 1 file, all parts will most likely be shipped in 1 bag (1 bag per model) and this could cause parts to break each other.

So please bear with me till I have a second discussion after printing

Ps. the 18 different models (not even particular related) caused another discussion (which is why several managers were included) as this meant Shapeways is paying the handling cost of 17 model while the customer only pays 1.
Right now it's allowed so don't worry, you're fine

But it did raise the question if it was fair for Shapeways to pay for handling all these models.
I expect that this will another conversation soon too (change pricing model like pay per shell for example)

Customer Service Coordinator
Shapeways
Re: Understanding the Minimum Wall/Wire Criteria [message #77127 is a reply to message #77118 ] Sun, 20 October 2013 11:44 UTC
 MitchellJetten wrote on Sun, 20 October 2013 10:37 It's going to take me some time to have a correct answer for you.

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

 Quote: The biggest issue here is: the ladder is reallllyyyyy fragile, printing won't be a problem at all.

Stands to reason that MÃ¤rklin 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.
Re: Understanding the Minimum Wall/Wire Criteria [message #77151 is a reply to message #77117 ] Sun, 20 October 2013 21:23 UTC
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.