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Dec 2016

Is anyone else having the issue of not seeing any images on this post? The only image I can see is one down here in comments that’s supposedly showing how support material should look after a print, but is showing a part still being printed with the support material still on it.

Hi @PepCo_Parker, the images are still in progress. We’re currently printing the same part again and again to show different print qualities, which are acceptable and which are not. The picture in my comment was just a quick snapshot I took with my phone while printing.

It would be nice if 3dhubs did not have to do this. This should really be handled by the hub. I know this is not happening, and this is why 3dhubs is trying to fix the customer expectation every time, because the number of complaints is too high, which costs them and the hub revenues when resolved. I know I am a prolific communicator on every order, and have even had customers exasperatedly declare to “just print it!” This is worth it, every time. I have had good luck with my reviews, and almost always it is about typing a lot up front!

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Support marring is a complicated issue, and needs a lot of explanation. For a small thin overhang that requires a little support, the print should show little marring. For a larger, wider, longer, flatter section that requires support, I tell the customer they should expect a very rough, marred surface.

This is because on a such a supported area, the surface is mostly bridged across the support material, and will sag minutely as it is printed across that area. The more of this that occurs, the less perfect that surface will be.

Additionally, support material across long surfaces also means that section of the print is being printed on less stable terra firma, and is thus going to be subject to a little more “wiggle” as the print is occurring, resulting is much messier surfaces on long, wide, flat surfaces held up by support materials.
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As for warping, shrinking, and corner curling with high shrinkage materials such as ABS, the customer should always be told this is a possibility or expectation. I always communicate this to a customer who has a print with large, long, flat models. I don’t have the issue usually, but I tell the customer it can happen, because I do not want to do a 10 hour print that the customer is expecting the next day, without them understanding that it COULD happen.

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Infill expectations I usually do not have to communicate. But it should be stated by 3dhubs, as it is unclear to many hubs what the minimum infill is supposed to be. I see many hubs that say they print 15%, but 20% is the minimum for 3dhubs, I believe.

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It would be easy for a large ABS print to shrink outside this tolerance of 1%, and I mention it as a possibility when ordering a print in ABS. ABS is a material used for injection molding, because it shrinks away from the mold so well!

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Additional expectations should be communicated to the customer when they order, by the 3d hub. Sometimes I can see the use of the model right away, and can see there will be no problem. A bust of Ceaser is all good with a little shrinkage. A phone case could easily shrink to the point of not being usable with ABS. Small holes in the objects are going to be the wrong size, almost always! So I always discuss these tolerances when I see them in a model.
A 10mm hole in one model, and a 10mm post that goes in that hole on the other model; I can almost always be sure there is going to be an issue. We are printing in a smashed hot thread with FDM, and it is going to smash outwards a little. If this is the case, I need to discuss it with the customer.

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I always type a lot before I accept an order. It takes time, but it is always worth it. It is all about looking at the model, material, etc., and discerning the use of the final print, or asking questions when that is not discernable. I ALWAYS want the customer to get what they want, not necessarily what they think they want.

I just did a quick review of some of my comments with customers, these are real:

-the posts on the thingiverse raspberry pi case will be very weak, and will likely break off if they are not careful

-some ABS orders should be printed in PLA

-gold PLA will not look like gold, it will look like plastic.

-get the drill bits out, because it will not work without it

-support material is going to leave your model unrecognizable, lol

-white will look better than black

-using it for cosplay, and going to paint it grey, it should be printed in grey, so that when it chips, it will be less noticable

-I cannot accept the laptop stand you designed, because it is so weak it will simply collapse

I am never shy about adding costs to the order for things the customer needs, like stronger infill, more shells, or better resolution. I offer .4mm layer height, because some customers just want a quick, cheap prototype. But I get orders from customers at that layer height, and I have to tell them not to do it! And I have had 3 orders where I told the customer to get it done with SLA, even though it will cost more and possibly take longer.

This is all key to a good experience for both parties. I have even told customers to get the order in PLA, and if it did not work out, I would reprint it again in ABS for free, to get them to switch away from a shrink prone disaster. I have never had a customer get it reprinted.

@cobnut

Thanks for that, that is pretty good! I would have printed that part, and it would have been off by 25% of the width of the hole in my nozzle, on each side!

Sorry, I had an attack of Friday afternoon mischief :slight_smile: As it happens I’m doing an order now where the customer needs very accurate dimensions. One print had an X of 117mm and it came out (in ABS) as 116.68mm. Pretty happy with that but an going to reprint at 100.4% to see if I can get closer.

I did not know remember that in the FAQ, and sure enough, you therefore have every right to expect it. It really is a bad term to use for complaint resolution. Wow, that needs to be a different phrase.

As for your price point, that is exactly the key. Realistic expectations for the technology, and thus realistic expectations for the price.

There are more perfect ways to 3d print, and less perfect ways to 3d print, but there are probably no perfect ways to 3d print.

But sometimes the customer is looking for that perfect price point, in which it is likely FDM will be more perfect!

I do want to add that guaranteeing dimensional accuracy is a bit of a point of concern for me. I am not concerned by my ability to meet it, I am concerned by customers potentially misinterpreting what that means. Guaranteeing dimensional accuracy does not make any difference if the part is poorly designed; i.e. the design of the part does not take into account tolerancing for mating parts and such. This is the classic example of making a 2 mm hole for a 2 mm rod; even if the hole is perfect, the rod will never fit into that hole, because the hole does not take into account dimensional variations that will occur in the rod. It will need to be made explicitly clear to customers that this guaranteed dimensional accuracy is based off of the model they provide, not what they intend it for. If a part is provided that is 2"x2"x2", then it is only the Hubs responsibility to make sure that the print is within your set dimensional variation.

My other concern with this is that it’s a royal pain in the butt to get dimensions from STL files as that is not really their intention; STL files just contain information about the geometry of the surface but contain no data about dimensions. If 3D Hubs is going to implement dimensional accuracy requirements, either the customer needs to provide the dimensions (such as via a drawing or by filling out a form), or Hubs needs to require uploads of parametric models instead of/along with STLs. I do not want to be held responsible for a dimension being wrong because I more or less need to guess as to what the dimension should be. Just my 2 cents on it.

This raises a good point, a customer may ask for money back on a part that is according to them dimensionally inaccurate as it doesn’t fit into other parts, when in reality the issue may be the part design itself. This would be very hard for 3D hubs to gauge when siding with disputes. Almost impossible I would think in fact.

If the issue is with the part design, then it is the fault of the customer if the final print does not work as expected. Tolerancing is a core tenet of mechanical design; if you brought a poorly designed part to any prototyping shop, it’s on you if things don’t work once manufacturing is done. If a print is within the allowable accuracy range (1 mm or 1%) then it’s not the Hubs fault.

Shapeways and any other larger print shop is very much what you see is what you get; as long as they deem a part printable, they will print it but that’s it. If it was printed how it was supposed to, they do not care if the design itself was incorrect.

Yes but let’s say two parts were designed to fit each other, but we’re designed improper via a hole or gap being a mm too small or too large. Diagnosing these issues before printing is nearly impossible, and the customer could argue they don’t fit due to tolerances of the hub being poor. Both of these sides of argument are hard to prove unless you are there in person. With the way 3D hubs handles refunds I could forsee it being an issue