Preventing Rejections - Update on Project Caterpillar

Before I discovered this thread I had posted on another and have since got some useful feedback on why models that can't be cleaned may be rejected:
https://www.shapeways.com/forum/index.php?t=msg&th=13299& amp;start=0&
It would appear that the reason is primarily to avoid customer complaints due to retained powder rather than to try and re-use every last bit of material.

The saving I can achieve by making a 1/200 scale model varies widely but I'm guessing that it is typically 25% to 33%, maybe not a lot in absolute terms compared to the costs of printing in other materials but significant in relative terms. The largest saving I have achieved is 80%, but that was exceptional. As well as reducing the cost making models hollow has the advantage of making them lighter which is of practical benefit when they are mounted on tall flight stands. EG (sorry, these models aren't 3D prints, they're OOP CLIX models for Crimson Skies):

Shapeways doesn't charge for trapped material. If you have an item that is hollow, but with no hole at all connecting it to the outside shell, the software automatically removes internal geometry. This was implemented years ago to prevent double charging for overlapping geometry.

This is why I try not to do what I just did, because it just makes me look stupid. So maybe you can explain to us designers why it's so important to have such a large hole if Shapeways isn't concerned about trapped material. Wouldn't a 1mm hole effectively be sealed in WSF, without the need for fusing the internal material, and solve the whole overlapping geometry issue?

My take on this is;
1. You are charged for the printed material by volume.
2, The support powder for WSF is the same powder that is used to make the model
3. Unused powder is recovered.
4. Shapeways are a business, their whole point of existance is to make money.
5, It is not good business practice to give away money.

Why not arguee that is takes less man hours to empty a solid object so that we all get a cheaper printed build?

Paul

My guess is that one rule is simpler.

WSF is its own support material and so anything reclaimed from a hollow model can be reused. This means that Shapeways has an interest in cleaning our models when the unfused volume is significant, for small models the key concerns appears to be avoiding loose powder.

It might be a difficult call for an inspector to make:
- This model is small, the escape/topology hole must be small enough to ensure it is sealed.
- This model is large, it must have adequate cleaning vents.

An additional complication might be caused by the weight of unfused powder causing structural failure in some cases.

Personally I would like a 'self sealing' small model option for hollow strong flexible materials, just not sure how Shapeways could specify it.

No need to feel stupid. There is a lot to learn, and many confusing rules. Shapeways is learning as we are. Not only the demands of the community, and the market, but also the limitations of the machines and processes. I've been here for years, and I still had a model rejected in my last order.

Currently trapped material is allowed in FD, FUD, and at least transparent detail, as these materials can visually benefit from having trapped build material in their translucent print. I used to offer a cube with messages inside that could be viewed when you held the cube up to a light.

The only reasons I'm seeing for allowing trapped WSF is to make the print less expensive. To try to counter this, there is a density discount for WSF prints. For models that are greater than 10% dense (material volume divided by bounding box volume), after the first 20cm3, the remaining volume is calculated with a 50% discount. We try to offer a finished product to customers, and having trapped material (that has no purpose to the product) or products that leak powder, is not a finished product. There is also the point that the left over powder can be reused, but that is not as much of a driving point as the powder isn't 100% reusable. The unused material is still effected by the processes of printing.

So what you can do to save some $ on your prints, is put multiple pieces in one file. For smaller items it is recommended to either join them with sprues or to build a cage to hold them together so they aren't loose in the build.

As a by-the-by and sort of on topic

Shapeways have now said that my previously-unprintable-due-to-flow-issues small mobius pendant may be printable in premium silver as long as the production team are careful when they polish it

paul

Hi,

another customer order was canceled today.
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Crown Ring (US Size 12) in Silver Glossy
Reason: Thin walls
Additional information: 0,2 mm
0,2 mm will be gone after polishing
-------
The design rule says: "Min Embossed Detail: 0.3mm (Regular & Glossy)"
In the screenshot the support provided you can see that it is 2.83 mm. I would round this to 3 mm not to 2 mm.
This ordere was canceled cause an embossed detail was 0.017 mm too thin?



Most of all I dislike that customer orders get cancelled without the chance to fix the issue. This customers are mostly lost and they don't buy again.
Guess this was suggested before, but it should really be a feature that allows the designer to send a new model within 24 hours, otherwise it might be cancelled.
With the "personalize" technique, there is already a similar message and upload feature implemented which I suppose could be enhanced.


Michael

Funny, but not true.

That's netfabb Studio, wall thickness measuring.
The indicators are the blue dots right behind the values.

To your first part, the line is .3mm. Even .299 would fail.
To your second part, I'll make sure it's brought up in discussion again.

I'm glad I am not alone. I have a part which I have successfully printed over 40 copies in FUD over the last year or so which has now been rejected in my last batch file which contained several copies to minimise costs. To be fair it also contained a test design which did have valid rejection issues.

The item concerned has a 1/16" square shaft about 20mm long which has a fine hole down the centre. The item is not sold directly as I clean out the hole to take a steel pin for both strength and provide a point - it is a height gauge which I sell on my own website (see here). The rejection image showed the wall between the shaft edge and the hole was too thin. I suppose it technically it is but I've printed 40+ without it ever being a problem.

My big dilemma is I can't change the shaft dimensions and there is no way I could drill the hole out if it were solid. As it stands I will probably have to redesign the whole thing to include a separately manufactured metal square rod which will substantially change my cost basis and prices.

As noted by others why can't the fact that a model has successfully printed before allow it to proceed. Unfortunately this time it was a seemingly new model containing several copies of previously successful parts. Otherwise at least allow the designer to add an appropriate comment to that effect.

This has really dented my confidence in Shapeways.

John

I'm not familiar with the output of Netfab. But there were small areas under there that I would classify as detail as they were about 0.3mm square and 0.23mm thick. Easily fixed but not obvious, and this particular model had been successfully printed before the rejection.

So it happened again. Someone discovered my store, got all excited about my designs, ordered a whole bunch of stuff, several of which have been there since the dawn of time (Shapeways Beta) and received a whole bunch of rejection messages. All of the items had been previously printed several dozen times, but that doesn't seem to matter. Shapeways seems to be relying exclusively on NetFab instead of their own brains. Oh look! There's a 4mm long encased feature that isn't a full 1mm in diameter! Reject! Reject!

Hi Roy,

this really sucks. Even if you've made a testprint, you can not make sure that it will be printed for customers again. This rejections are killing all the fun.
I can't imagine that it is cost-efficient for shapeways to check a design every time it gets printed. A model that was printed hundred times will be checked same as a model that was never printed before!? Whay not flag it as "printed before" and skip all tests on it. Of course it should loose the "printed before" state, the first time it causes trouble during the print process. I would pay gladly more for printing generally to prevent that customer orders get canceled.

Michael

I would pay good money, say $20-$40 to put a model through a full validation and NEVER have to worry about it again. As it stands I don't dare take out magazine ads, send models to bloggers or other professional reviewers, or anything else that takes time and money for fear that Shapeways will take all my work and throw it out the window as soon as somebody orders it, regardless of how many times I test print it. I have no idea how some people are making their living doing this.

Is there a standard time frame for alerting us of rejections? I have had everywhere between next day to up to five days before my order is cancelled and I am notified that my files are not in production. I think it would be really helpful if we were able to expect notification within a shorter time period so we can attempt to rectify the situation and still be able to meet our own deadlines.

Hi, I have the same problem, was directed to repost here to underline the seriousness of this issue.

It all depends at what step the item fails. The file is manually checked in the first few days. When it's sent to production, it can fail while printing, or, depending on the material, when being removed from the print tray. After that, the prints have to be cleaned, and in some cases finished. Some items are printed at Shapeways, but some still have to be shipped to Shapeways, where they are checked, packaged with your other pieces, and sent to you. So a rejection could happen a day before it's supposed to ship if it arrives at the factory broken.

Again a customer order was rejected cause of an issue which is (as far as I know) not part of the design rules!
And again I had no chance to "fix" it before the order was canceled.
------------
Snake Ring (Size US 9) in Silver Glossy
Reason: Can not be cleaned
Additional information: will bend
will bend. Has to be more connected.
-----------

This is so profound that it appears to be sabotage to me. :laughing: Compared to the masses there are only a handful of designers in the world highly familiar with the use of 3D design software as it pertains to 3D printing. Consequently, it would be very easy to perturb this small group so much that they simply move on. If I were Shapeways I would have everyone drop what they are doing and work to come up with a solution to this ongoing problem.

Also, I hate to say it, but in connection with these rejections is making people ask for their money back. NOT GOOD! I don't know how it is in Holland, but I know I myself was highly perturbed by this! It causes people to think things along with the being upset about the rejection. I haven't looked lately, but I have well over $100 that has been sitting in Shapeways' bank account and not mine for well over a month. And yes I know why Shapeways does it that way. And no, I don't need my money back, if I did I would have asked for it back, I'm simply telling you people don't like that when it is in connection with a rejection. It will cause them to think all kinds of negative things in conjunction with the rejection.

Why can't Shapeways simply tell everyone that a new item is in research and development and what is involved with the development? And then once the item has been printed successfully 25 times it would then attain a full production status with no restrictions.

Another thing Shapeways should be doing is sponsoring designers. Wherein, Shapeways would help with R&D of new products, photography and marketing. One idea might be to print a number of items of select products using unused space in the printers to have on hand an inventory. This would allow for more optimized shipping times!

Also, price wise, Shapeways needs to decide whether they are a retailer working for itself or a wholesaler working for the designers who are the retailers. And shouldn't there at least be more robust marketing research available?

Have there been any attempts to develop a relationship with any of major retailers? Wouldn't it be awesome if Shapeways shops could directly connect to Amazon or eBay?

I've been reading the forum since the very beginning. I know everyone here. It's only recently that I have started participating. I'm on Shapeways' side and I'm rooting for Shapeways to succeed! So lets make a better future!