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Dec 2016
34 / 116
Dec 2016
Jan 2017
chrislloyd
Dec '16

Hi @cobnut Yeah that makes sense in terms of the general nature of the guidelines. And I agree that it remains down to me to specify what I need, but it is difficult to do that at first and I think some people may get put off by the difficult entry barriers. However, in the spirit of pushing the industry forward, in terms of quality and applicability of end use, I would stick with the need for dimensional accuracy and perfect finish. If I am a minority in this, then clearly they don’t need to go into the guideliness.

I guess there are two streams here, one which is focussing on low cost prototyping where these things don’t matter so much and the other is expanding into the production of finished parts. I see a bigger future for the industry in the latter stream.

cobnut
Dec '16

Hi Chris, first of all, I should point out that these guidelines are for FDM only, and FDM has specific issues that don’t apply to SLA or other print methods. If you need “perfect” quality, it’s possible that FDM isn’t the most appropriate technology (although of course, some FDM prints can be very fine indeed).

I don’t think you’re necessarily in the minority, I think you’re right that broadly speaking there are two types of print being made here; prototypes and “finished parts” (and, of course, both these categories can be split down further). I (try to remember!) to always ask customers what the print is for but even if it’s a prototype I don’t see that as a reason to compromise on quality and things like dimensional accuracy can be just as important for prototypes (after all, a prototype is often used to test fit, etc.).

Where it can be an issue is where supports are necessary. As we’ve discussed earlier in this thread, supports can often leave an uneven surface - it’s simply the nature of FDM printing; it’s virtually impossible to get as smooth a surface on top of supports as on a surface printed directly onto the bed or as a top layer. If the print is for a finished product, this could be a problem (depending upon whether the surface is actually visible (sometimes they’re parts that are built in such a way that this surface isn’t external), but for a prototype it may be no issue at all.

Enza3D
Dec '16

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.

PepCo_Parker
Dec '16

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.

Enza3D
Dec '16

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.

PepCo_Parker
Dec '16

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

Enza3D
Dec '16

That improper design will show up in the model, and that is why I suggested also requiring either a form/drawings or parametric models. If the feature in question is in the model, there is no argument about who’s at fault and parametric models display all this information with a couple clicks. It is not the job of a Hub to comb through a model and find problems, that is the job of the designer to prevent in the first place. If a feature is designed to be 10.5 mm wide, and the Hub produces it with a 10.1 mm width it’s correct by 3D Hubs definition. I know each Hub handles this differently, but this is the reason my Hub does not guarantee pieces will fit together unless we designed them. It is on the customer to make sure the design is correct, we just make what they give us. If we design it, it is designed with appropriate tolerancing for any mating features and I have no issue guaranteeing it will work because I made it and know what I am doing and the tendencies of my printers.

This is also why I think implementing a guideline like this will cause problems, and I agree with you there.

Odense3DPrint
Dec '16

@Robin3D has an “official” test piece been made?

i want to be on this “wagon” since it will indeed ensure somewhat a minimum level of print quality

Also how will you verify this? i could imagine that the hub print the test bit an use a caliper and photo document that it can be printed right.

Just like that you have to print a marvin when you create a hub

And while at it i think that there should be an option to reverify this… ie when hub rebuilds printer etc

Joerg_4
Dec '16

Good points, you are absolutely right!

Hopefully one of the 3D Hubs officials will reply to your post, may be @Robin3D

Cheers,

Joerg

Robin3D3D Hubs Employees
Dec '16

Hi @Boelle,

That’s correct, the FDM Quality Guidelines will be the same for all FDM printers. We can’t expect every customer to know what kind of quality they can expect from a specific printer model/brand so that’s why these guidelines will set a standard for all FDM printers.

Best,
Robin - 3D Hubs

Perry_1
Dec '16

@Enza3D you are so smart.

Yes, there is no way, outside of the dimensions of the final X,Y,Z part, that a tolerance can be checked, in any realistic way, without donating hours to each model.

I would assume we are not being asked to load some software, put the model in, check the size of all the various features, check the tolerances on each, etc., and make sure they are all within spec.

SO, this dimensional accuracy should always be on the final XYZ measurement, as the tolerance “guarantee” if you will. The size that is displayed on the 3dhub page, or in the slicer software as bounding box size, if you will.

Robin3D3D Hubs Employees
Dec '16

@Enza3D, @Joerg_4, @PepCo_Parker, @Perry_1

Hey guys!

Thank you all for expressing your concerns and giving me your feedback. I really appreciate it. The reason that we have to set guidelines on dimensional accuracy is because we have to draw the line somewhere and we thought setting a 1 mm tolerance would be a reasonable first step.

I completely agree with the fact that you, as Hubs, cannot know the application of your customer if they do not communicate it. Ofcourse in some cases you will have an idea by looking at the design that it’s part of an assembly and in this case you can double check with your customer if a 1 mm tolerance is sufficient.

But in most cases this is not the case and also, not your responsibility. If you receive a model from a customer and you print it within the guidelines that we as 3D Hubs set, you will be paid out for the job no matter what.

When a customer is not happy because the print does not exactly fit, we will ask them to take a photograph of the print next to a measuring device such as a digital caliper to show the exact size of the print. Of course we do want to keep our customers happy but this is not always the responsibility of the Hubs.

Feel free to reach out to the 3D Hubs admins (such as myself) at any point if you have a situation where the customer is not happy with the result but you printed the part according to the guidelines, we’ll definitely be able to help you resolve such a situation.

Best,
Robin - 3D Hubs

PepCo_Parker
Dec '16

Hello again Robin, So to me this means hubs will have to start watching our backs by taking photos our selves of parts with calipers next to them, it wouldn’t be hard to fake photos to make it seem like parts aren’t the right sizes when they really are. This would be the only way to insure people aren’t cheating us out of good parts, but even then now we have to charge for our time photographing and setting all that up

Enza3D
Dec '16

My costs are definitely going to go up because of this; even if the verification is for my own insurance, it’s now another step I have to do for every print and that will be reflected in my prices. Because you’re right, there’s no way to prove it is correct unless I have already verified it myself and have pictures of it.

The problem is, how do I know if a dimension is right or not? Unless I have a parametric model file, or the customer explicitly specifies the dimension of a feature, I have no way of knowing (other than guessing from the STL) if it is correct.

PlastiPrint3D
Dec '16

My issue with these guidelines is quite simply the policing of them. Are you going to ask the customer to send you the 3D print so you can verify the dimensions yourself and make a ruling on it? Not every customer will have a set of calipers and even if they do, use them correctly to get an accurate reading.

Also this requires that I record how each model has been orientated in the slicer as your tolerances are in the X,Y and Z axis however that’s not to say that I printed a model along these axis. What if it’s a curved model that was printed at 45 degrees so that while the length of the curve is beyond the 1mm tolerance, the actual readings in the X,Y and Z axis weren’t?

And lets get something else right here, these guidelines aren’t designed to make my life as a hub easier, they are designed to make 3Dhubs job easier. I am now going to have to record, document and photograph more details of a print before sending it out.

PepCo_Parker
Dec '16

That’s exactly my point. How could someone say what the customer shows tolerance wise is correct? It could very easily be wrong or misleading. In reality, 3D Hubs up until this point has in my opinion been running a great part just on mutual trust. If a customer requires a specific tolerance, as far as my experience goes they would specifically address this before I accepted the order, and I could respond accordingly. Same procedure as asking about infill, layerheight, material, and colour. Has tolerances become such an issue suddenly or is this merely a non existent problem being fixed. ‘Don’t fix it if it ain’t broken’. All I have to say is this is definitely going to impact customers who may have preferred just a cheap part and didn’t need tolerances greatly. It will certainly force us hubs to constantly watch our back now as an unruly customer can backlash quite easily and request an unfair refund. And I don’t mean to be Curt, but don’t respond saying all disputes are handled fairly. I have had situations before where I should not have lost money on jobs, but had to accept as 3D hubs heavily pushes for the side of the consumers. As well a fight in that situation would most likely have lead to a poor review and hurt my hub greatly. We are already at the will of the consumer, this is just giving them even more un necessary power. If a customer specifically needs a certain tolerance then I don’t see why they can’t just request this, why does 3D hubs specifically have to get involved?

Enza3D
Dec '16

To keep it even somewhat fair, Hubs would have to physically measure the part themselves. A customer could easily take the pictures at a skewed angle to warp how the print looks or improperly calibrate calipers so that the device measures incorrectly. If a Hub hadn’t measured the part themselves, they have no defense in the dispute and I don’t think this thinking is being paranoid either. It’d be a quick way for a customer to get prints completed for free, and for larger jobs, I can see this happening quite a bit. It’s very easy to edit photos, and I will not accept that as the only way 3D Hubs decides if a print order was completed correctly or not.

If Hubs wants to implement dimensional accuracy requirements, then that’s fine but you have to be able to implement it/police it fairly and provide your Hubs with the tools they need as well. I feel like a broken record here, but getting dimensions from an STL file is inaccurate and inefficient; if I need to verify dimensions are correct (which now I do), then I need to know what they are in the first place. I can only do that if the customer tells me what they are in a drawing, or if I have the parametric model. I can ask a customer for the file, but if they don’t have it and can’t clearly communicate what dimensions are required, these new guidelines will force me to turn them away. The risk is too high otherwise.

astroroxy
Dec '16

I don’t like the idea of standard support removal, as I like to leave on as it helps protect the print while shipping.

ProDE_E_3D_HUB
Dec '16

Hi Robin3D,

I think it would also be helpful if you could clearly mark on the photos what is wrong by placing an arrow or circle on it.

Not all that is on the photo will be not acceptable I guess.

Thanks! Keep up the good work!

Best regards,

Sandra

PepCo_Parker
Dec '16

Anyone else getting the vibe that regardless of the communities concerns 3D hubs went into this conversation with the mindset they were going to do it, and rather than maybe delaying the launch to address these issues and concerns they just ignored them and launched anyway?

PlastiPrint3D
Dec '16

Unfortunately yes. The managerial speak trying to make it sound like it will benefit me as a hub and big warning across the top of my dashboard saying it’s happening tells you all you need to know.

It’s getting towards the point where I’m considering if I want to be associated with 3Dhubs as the requirements are starting to pile up for the little cash you get back from the job.

cobnut
Dec '16

Well, as far as dimensions are concerned, any decent slicing program will report the printing dimensions of the sliced model, so there’s no need to guess. In terms of getting the prints right (accurate to those dimensions) why shouldn’t they be? I know all my prints come out well within the tolerances suggested by 3DHubs so I don’t see the concern. I always check with a customer what the purpose of their print is anyway, and if I now have to remember to also specifically ask about tolerances, that’s really no big deal - heck, we could all easily put together a stock “first question” to cut and paste for any print order that covers things like this.

To be honest, I’m not seeing a problem here. If I were a customer, not a Hub, I’d expect there to be controls like this and I’d expect the printer to deliver me high quality prints that match the model I’ve uploaded. If my model is unprintable, or I want a dimensional accuracy that’s unrealistic, then that’s another matter, but the tolerances being suggested here seem very reasonable and totally what I’d expect from a paid service.

Sorry if this isn’t a popular view, but I can’t see the problem with wanting to produce high quality prints that match the customers’ requirements. Have I missed something here? Do the majority of Hubs often print models with inaccurate dimensions? Does no one else discuss the print with their customer to get an understanding of the job and any specific challenges?

Enza3D
Dec '16

@cobnut The issue with using STL models for dimensioning is that they are dimensionless; what we get in a slicer is just the software’s representation of hundreds or thousands of triangles. Because of this curves become faceted, so if a customer has a small hole and they did not export it properly, they could easily end up with a hexagon instead of a circular hole. It’s just infinitely easier and more accurate to work from a parametric model than an STL file. It’s just poor practice in industry to dimension from STL files. To be clear, I do not have an issue with the set dimensional accuracy range or my ability to meet it. I have an issue with the complete lack of discussion as to how it’s going to be policed (sorry, but a picture won’t cut it) and the space for misinterpretation on the customers side as to what that means. I have already had to deal with customers giving me the wrong file and wanting a refund because it was “printed wrong” but the model was fundamentally wrong to begin with.

PepCo_Parker
Dec '16

My concern isn’t hitting the targets, it’s people manipulating the system in their favour to receive free parts. Stl files Do Not show dimensions. Only overall. This will not show dimensions of inner details and walls. These new standards make it easy for someone to set a pair of calipers improperly and fight for a refund. Meeting the requirements is not at all the issue and I urge you to please read what we have discussed in the past.

PepCo_Parker
Dec '16

As well if you had read my post, I expressed that I felt a large part of 3D hubs is just mutual trust and proper communication. I explained that my practice has always been to discuss with the customer what is needed for the part and if tolerances are needed. So my question is why does 3D hubs have to get involved now? I saw no issue with the system before. Really feels like they are simply creating problems to fix.

Perry_1
Dec '16

@PlastiPrint3D So I do not see this warning. Can you cut and paste it here?

@Robin

So far, I am uncomfortable with the wording that has been provided. Perhaps we could give some input on that before it goes live!

John3d
Dec '16

remember with out our printers 3d hubs would be nothing you have a voice there is no benefit that i can see for a hub with the new rules apart from more work for us.

PepCo_Parker
Dec '16

Maybe instead of enforcing these rules the way they are, they should have provided tools to educate hubs on better ways to quote and accept an order, such as good questions to ask and topics to touch on when explaining. If people not getting the tolerances was an issue, this was not the way to go about it. Unfortunately it doesn’t seem 3D hubs really cares for our opinions on that, the distinct lack of response from any of their employees is only even more evident of that.

PepCo_Parker
Dec '16

Unfortunately with the amount of Grant money 3D hubs has received recently, our opinions really don’t mean anything. I’ve seen this time and time again where as soon as big figured come into play management goes to shit. Very disappointing. This whole thing is really pushing to go off 3D hubs for business, which was not something I wanted to do. A year ago, all I did was promote 3D hubs as I liked what it was about, and how their aim was to educate people on additive manufacturing. I can’t help but think they’ve lost their ways since then.

rkelly
Dec '16

To further this point, 95% of hubs and 99% of customers do not have sufficient metrology to measure the things that are being printed. Bounding box dimensions are a great tool to get the relative size of a part in a digital space but are useless in the real world. Most prints are not rectilinear and are impossible to measure short of scanning them back into the digital space and comparing them to their source file. Taking a photograph of a print next to a ruler or with a caliper are both useless verification methods unless focal length of camera and a bunch of other easily manipulated factors are taken into account. To validate a dimension the measuring technique has to be objective.

How about instead of holding hubs to a ridiculous standard of quality which are unenforceable and will undoubtedly increase the cost of every FDM print and reduce overall ease of use for this whole system we add a step to the verification process where the hubs have to verify the dimensional consistency of their machine. Hubs could print several calibration cubes and either send them direct to 3D Hubs headquarters or measure them, similar to the initial marvin. This could even be a periodic check. This would be like a drivers license, you need to prove you can do it once or twice and then you’re left alone. Asking for every single print to be measured increases the cost and significantly reduces the appeal of 3d hubs in general for both the customers and the hubs. I truly understand the spirit of what it is you guys are trying to do but implementing blanket rules that cant be enforced without tons of effort not the way to do it.