Thin Walls

Uncookedtrout, it's not just an issue of what we, as customers, want with wall thickness, there is aso a physical print consideration. A few examples; WSF has a 0.7mm wall thickness because much thinner has the possibility of breaking off during the print process and ruining the whole print run. Stainless steel is printed as a steel powder bound together with an organic binder, the part has to be handled and cleaned before it is infused with bronze. The thinner the part, the less likehood it has of survivng.

You could contact Sapeways direct via the contact link at the very top of the page to see if they would be prepared to go with your idea, they've entertained thin/small parts in the past with the detail materials.

Actually uncookedtrout this has been answered before but not in a definitive yes or no terms. From the responses i'd say the answer is actually No, shapeways cannot print items in exception to the wall thickness policy. A lot of people debate what actually the limitations are for but its a mixture of quality, printer limitations, worker limitations, and general safety at issue.
Quality clearly degrades below a certain detail size but also a part breaking off your model can damage other models printed to different specificaitons.
As pointed out before printers can't actually print below a certain point, this goes beyond just detail loss but actually results in entirely missing structures which may cause items to crumble or warp.
Again items of small size present problems human workers can only do so much to save pieces which are printed to thin, handling and washing can cause damage and each time they destroy the piece they have to start over wasting their time and materials.
I've read about 3d printers breaking when they get clogged by small items. To the point that they've caught on fire because of clogs. Its rare but it can happen. breakage is pretty common when dealling with machines that are abused outside of their capable perameters.

Hi,

Replied to this thread instead of a new post, to find out if I understand the concept of thin walls directly: any measurement in any axis/dimension/XYZ that is more than the minimum wall thickness is a 'wall', otherwise it'll be treated as a 'detail'... did I get it right?

Please consider the attached/below screenshot of a model battleship to be done using Frosted Ultra Detail (minimum wall thickness of 0.3mm)
https://www.shapeways.com/model/318339/french_navy_battleship _pack_1.html



A. Red:
1. the first level, extruded from the ship's hull is around 0.6mm x 0.4mm x 0.2mm... therefore a wall if I understand correctly?
2. The next level would be like a dagger/cross, with each cube at 0.11mm; thus whole cross structure is 0.33mm x 0.33mm x 0.22mm. Is it considered a wall (if measured from the front cube face to the rear cube's face) or detail if the smaller cubes are considered?

B. Yellow
1. level 1 is a wall, certainly level two even if it's just 0.1mm, correct?
2. level 3: each 'box' is 0.11mm x 0.2mm x 0.15mm; intentionally designed for the gap to fuse upon printing... a detail then?

C. Green
It's a 0.11mm diameter, 0.15mm tall cylinder stuck to the side... detail yes? Unrelated, but will it have any problem printing like being 'too small'?

The model will probably fail the process due to numerous 'thin walls', just wanted to confirm that I get the concept right this time before continuing...

Cheers!

First: I have from time to time emailed Customer Service (service@shapeways.com) to request a "Thin Walls Check", on a model which they have done gladly. I do try to keep the number of those requests to a minimum, so as not to overload them with extra (unpaid) work.

Second: I'll try here to give you my (personal) perspective of "wall" versus "detail". I do wonder if some of your parts are going to have difficulties. I may be completely wrong, but I think all three areas you've hilighted will pass. I have a bit more concern about the post that is sticking up just above the green area, and the two horizontal posts to the right of that. How big around are those posts?

What has worked for me is this analogy: Rivets along a surface are Details. Wires/Ropes/HandRails attached to "anything" are Walls.

In mathmatical terms: ANY open plane (ignoring the edges) must meet the wall thickness (WT) rule if its distance to a supporting peice is greater than WT.

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Your models look to be some extremely nice work, I'm very impressed. My biggest concern would be your gunbarrels. If they are longer than WT, then they need to bigger around than WT.

Thanks stonysmith, much appreciated! I'll keep it mind about CS.

Indeed the vertical one will give a positive: it's 0.17mm x 0.37mm; the two horizontal ones are 0.11mm x 0.18mm up to the vertical face under them but are up to 0.58mm to the middle structure. These have been updated, but not yet uploaded: the whole model/s are being worked at, as there are structural parts less than 0.3mm (for FUD)

The gunbarrels to the right are also being worked on: 0.31mm diameter, with faux support underneath...

Thanks again and cheers!

I just got an interesting reject..

On my order the T10 x3 rejected but the T10 x6 was fine (turns out I had ordered the T10 x3 by mistake) but what makes this really interesting is the only difference is the number of T10's in the file, the rest is indentical !

Wall thickness is not automated. a person actually has to press a big red reject button or something. Its often a matter of their oppinion.

Hello. It's my first post here I have question - is it possible to print that kind of beams in FUD? One side is touching thick wall.

In a word, No.

The 0.2mm on the outer side will be rejected as too thin. Make it 0.3mm and it "might" be accepted, but.. You may find that that "L" shape sticking out from the wall will crumble under the slightest handling. 0.6mm is considerably safer.

Hello there,
the 'thin wall rejection' issue is so manifold, may i add another aspect:
Models which supass a certain size, and shall be printed in WSF, must have an even bigger wall thickness. Everything with edges /sides over 12cm (or so) must be at least 1mm strong. The length parameter is applied on the longest side. Reason for the need of an even bigger wall thickness is, that the WSF starts to deform due to thermal issues.
What i am interested in is: Is the 'longest side' considered the longes continous model element, or the longest total dimension of the model?
As example a screenshot of one of my models. Its total dimensions are something like 19 x 19 x 2 cm. But as you can see, the shape is cut into pieces, which are held together with support beams of 1mm diameter. The longest edge length of the model would be well under 10 cm (approx 9cm).
How would Shapeways apply the size of model / wall thickness rule here?
Based on the overall dimensions, or based on the longest 'real' edge?
Best regards,
Heiner

I am still having problems withSHapeways and models that I have had many prints from before, now getting rejected after getting fixed before the last lot of prints..

https://www.shapeways.com/model/340546/1x_klingon_k22_1_5000. html


https://www.cbfasi.co.uk/Files/355872_-1.jpg


The thickness on the wings.. easy fix, but the front of the bridge... its already been printed, and its part of a curved area, the background grid is 0.5mm, changing this will make a major change to what is a scaled ship.

Did you ask service@shapeways.com what the reason for the (new) rejection was?

I got sent the unedited version of the image above. Thing is the previous prints of the same model are perfectly fine and the model has not changed

Send it back to them and asked "What changed?" I've done this on more than one occasion. Sometimes, it's because a model is particularly troublesome while printing. It "works", but takes them 3-4 retries to get it to work.

Hi all,

been very confused with the min wall thickness issue.

To help me understand better can anyone tell me how they would go about checking this model (manually or with software) and whether it would be possible to print it in WSF or Sandstone? Any reasons for why the model could or could not be printed would be amazing.

Cheers

https://www.shapeways.com/model/964841

Download Netfabb Basic from www.netfabb.com. It's free.
Open the model and you'll get a big red triangular warning sign.. you've got one face that is not closed properly.

Click Repair (the red cross at the top left) and then on the 2nd tab at the right "Actions", click "Close All Holes".
Click "Apply Repair" at the bottom right - that one problem is now handled.

Then, click the purple-ish Ruler for measurements.
In the middle of the right-hand pane, select the wall-thickness tool.

Then, go about different places on your model and click. It will add a measurement at each spot you click.
Go about your model, measuring the spots that you think will be troublesome.

Overall, I'd say that your model looks good - very interesting design by the way - everything seems to be more than 3mm thick, so it should be fine to print in either FCS or WSF.

Advanced Instructions:

I thought I'd separate the two topics here slightly. Your model does have an issue of a separated overlapping shell that's not needed.

In Netfabb, select Repair.

Right click the model, and click "Select this shell" and see that it selects the main body of your model.
Right click again and select "Remove Selected Triangles" and you'll see that there are a couple of little floating meshes that are likely not a desired part of your model.

What I do is use the two steps above as exploration, looking for problem areas, and then I Undo the repair to get back to my original model unchanged.

Then: Right click the model, click "Select this Shell", and then right click again and select "Extract Selected Triangles as Part".

This pulls the main body out as a separate peice. As long as it doesn't have any missing areas, then I select "Export as STL" and write out the new model, without the little floating debris parts that the original had.

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The other way to handle the same situation of small floating peices is to upload the model to http://cloud.meshlab.com - it will union all the peices together for you.

Hi Storysmith,

I thought I reply directly to you because you seem very well in the knowing about Netfabb :}. I have been using Netfabb as you said for checking and repairing when I see the very big exclamation mark. So far so good. And I also check dimensions as you said by clicking on various parts. But I really wondered is there no automatic way of checking your object. I design a lot of wired objects, quite intricate and it is a tedious job to check every part, because apparently I have a blind spot to see where the weak spots are.

How does shapeways do it? Do they like, you say see immediately the weak spot and check it.
I would assume they have an automatic system that would check if the model parts have the minimum wall thickness. But I seem not to be able to find this way in Netfabb. I would like to type in 0,75 mm and do an automatic check if there is any part with less than this dimension/wall thickness.
I have asked shapeways how they do it and also I.competitive service (oeh can i name the competion 0-o) But again and again I don't get a straight answer and just refer to the basic page. I cannot believe they don't do this automatically and so it probably wouldn't be netfabb but an expensive homemade software
It makes it really frustrating to get the models back again after checking repairing like a lunatic. Also it is a shame that objects still cannot be uploaded with that rigorous check build in instead of paying shipping costs for no objects.

Thank you in advance for your effort for this short question with a lot of build up words and endings bla bla :}.

Greets Rivka

Most of Shapeways rejections come from a manual check just before assembly into the "build".
This check is performed by a human, using Netfabb (or a customized version of it).
The people doing this have seen thousands of prints, and can generally spot trouble areas just by sight.

I understand that there is an automated check done at the time of upload, but the parameters on that check are VERY loose. Mostly it checks to see that the overall boundaries correct, and is any part too thin for some specific material. That's why when you upload certain models, it's ONLY available in WSF or why it's NOT available in Sandstone, etc.

But, the actual (final) geometry checks are done by a human (at this time).

Netfabb itself does not do an automated check. You can use it to manually ckeck things, but if you miss something, the production people might find that one spot you missed. There is a new program out there (referred to in another thread) that seems very interesting to me. It will give you a "heat map" of your model with coloring based upon the thicknesses.

The problem with an automated program is likely going to be that it will fail airplane wings every time they are checked. The humans know that a certain amount of "tapering" is acceptable, but the automated programs to date don't make that decision correctly.

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One thing to understand.. not all models are rejected BEFORE printing. Shapeways actually goes a bit overboard TRYING to make prints work, and they lose a good bit of money on prints that don't survive being taken out of the printer, or they don't survive being cleaned, no matter how careful they are.

Hi,

Thank you for your answer. Very clear indeed, so my eyes need to be trained more. It is just such a disappointment every time when my models are rejected (not only for to thin walls though) but alas.

The software you talk about does sound very interesting, it would be helpful with checking the model, but I understand not to see it as a perfect check.
I tried to google it because on 'another' thread is a little to vague for me with all the thousands of threads that are going on. No luck though.


Thank you again.

Greets Rivka