Hi,
Yeah I appreciate ‘perfect’ is not a completely helpful term in this sense. Although the reason I used it is because it is used in the FAQ of 3D hubs quite freely and used in terms of what would happen in the event of a dispute between printer and customer. 3D hubs have an expectation that a print will be perfect, otherwise a refund is available. As such, it needs to be dealt with in the guidelines or removed from the FAQ.
Understand on seams (these were layers in my mind) I’m slowly getting up to speed with the terminology. My concern was for steps in the seams, where the print is misaligned.
I would love to move to other techniques, but realistically, at my price point i’m only interested in FDM.
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
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.
@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
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
@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.
@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
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
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.
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.
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?
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.
I don’t like the idea of standard support removal, as I like to leave on as it helps protect the print while shipping.
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
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?
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.
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?
@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.
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.
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.
@PlastiPrint3D So I do not see this warning. Can you cut and paste it here?
So far, I am uncomfortable with the wording that has been provided. Perhaps we could give some input on that before it goes live!
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.
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.
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.
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.
I think its mainly because they dont have enough feedback internally on the practicality and implementation of things they propose. This very much feels like a marketing driven company with very little engineering or maker feedback, which quickly turns into a circle jerk of corporate values and quarterly earnings oriented business moves. The customers needs will slowly get belittled until they are forgotten, all the customers will feel alienated. A new startup will pop up and cater aggressively to the core user needs and 3D hubs will fail as a business. Unless they start listening and discussing the issues at hand with us.
Hi Chris,
I understand your concerns as a final user, however wouldn’t be more easy for you and the hubs that print your cabinets to have a list with the specifications that you want your cabinets to be printed (i.e. I want them with so much infill and so much thick walls)?
That way both you and the hub will know what you want? To blame each hub that they haven’t print your part the way that you want when you didn’t gave them any specifications is a little unfair. And no 3DHUBS they should not make standard the specifications that you want your part to be printed because it is not standard for millions of other parts. So my suggestion is to submit your specifications when you place the order.
Hi all, newbie here, been lurking as I’ve got a cheap CTC machine I’ve had for a week and been playing with/upgrading, anyway, couldn’t resist weighing in on this one - I used to run a CNC mill for prototyping parts, and there’s no way in hell I’d agree to a 1% tolerance on most small plastic parts, especially ones made hot on the machine, even though I could hold far closer tolerances than that on the machine, why?
Well not only do you have shrinkage to deal with, but if the part relaxes over a few days whilst in shipping, absorbs some moisture whilst it’s sat in their workshop for a week, or you live in a place much colder/hotter than the customer, the plastic parts could have moved out of tolerance just through natural growth/reshaping. You could have a 1% change in dimensions just through normal room temperature water absorption rates alone on such as Nylon going from dry printed back to it’s more normal 2-6%
If you’re going to specify a 1% tolerance you really need to spec out whether that is relative or absolute, and at what temperature and humidity, and explain to the customers that their parts are going need to sit in a room with a controlled temperature and moisture level for a couple of days to stabilise so you can measure them accurately. Otherwise you’re going to have some real issues guaranteeing those tolerances on FF production parts which have all manner of internal stresses just from the way they’re formed, not to mention varying crystallinity not just from surface to interior but also on the filament skin to core. That’s not even taking into account any creep that might occur on the part later on depending on how and where it’s stored.