I think you want to hit on wording that both requires good prints from the hubs, and educates the consumer, while encouraging communications between the two.
Here is an example:
Dimensional accuracy. approximately +/- 1mm or 1%, depending on which is greater. Tolerances and spacing for parts that fit together should be built into the model. Please discuess tolerances for such items with your chosen Hub.
Surface quality: consistent, no delamination. Discernable details above .8mm. Please discuss with your chosen Hub if you have details below .8mm that are pertinent to the print.
Post processing: supports removed. As supports require additional time and material, there may be an additional fee for supports and support removal that is not reflected in the original quote from your chosen Hub. Surfaces that require support will have distinctive marring and will be less consitent.
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The key might be to try to get the customer to add some communications. I get a ton of prints that include no comment from the customer, it is just a model. So I am usually the person to start the communications, which is fine, but it would be great if we could encourage customers to add comments from the start!
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See Robin, I disagree with this. I think the communications should be in the opposing direction. We as hubs should not have to talk almost poorly of ourselves to explain that there are guidelines that this platform has put in place that are unreasonable. This right off the bat makes us hubs look suspicious. In my opinion, this is the wrong way to go about it. You guys should be educating hubs on proper communication with their customers, asking them if tolerances are needed to begin with, not forcing it upon them. This gives us hubs more control, and gives the customer a better experience. I know that last part for a fact as any time someone is new to 3D printing, I go through a little spew about it all and what to expect, what it’s good for, best materials for certain situations etc. Forcing these guidelines seem unnecessary and in my honest opinion will only create frustration for both hubs and consumers.
And that was exactly my point oh so long ago. This seems like a solution for which they are creating a problem to fit. I can’t stress this enough, if this was a problem then it was due to lack of communication not lack of rules. I really don’t think this is the way to go about this.
No offense Robin, but you’ve spat in our faces with this one. Basically what you have stated here, is that you took selected people’s criticism and acknowledged it, then based on those few views which you guys selected, you already had enough mindset to implement it, but them put up a forum post to again only portray the illusion that we had a say. And you may try to argue against that, but pushing the update through right before the holiday season, despite the discussion on here, only proves that. I dislike that a handful sampling made the decision for all of us hubs. It affects all of us, why shouldn’t we all have had a say?
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Maybe its me but I dont understand the big issue with a 1% or 1mm accuracy whichever is greater. Thats a quite large tolerance. If you cant print within that you need to work on your printing skills. I typically get under 0.2mm tolerance on parts I print. Looking at a part I did a while ago its off by .08 to .1mm
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No offense but if you don’t understand it, you haven’t read this thread. There have been numerous points as to why it’s not feasible, and I have even stated that hitting the targets isn’t even my personal concern, it’s people manipulating those rules to get free prints. I suggest you start at the top and read your way down to get a full understanding of the points raised.
Well the same customer that is going to manipulate these rules to get free prints would most likely still complain and get a free print without these rules. This is also why you should price your prints to accommodate for the once in a while customer that causes issues. Same with any business you need to weigh the risks and prepare for them or close up and find something else to do
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This is true, but tolerances as you’ve stated, have never been an issue for me. These rules seem to only be giving the customer more power over the hubs, when it’s unnecessary. If the hub communicates properly with the customer prior to the order being accepted then there should never be an issue in the first place. These guidelines make it easy for someone to improperly set up a pair of calipers, take a few photos and bam, there’s a 200$ order down the drain when the hub did nothing wrong. There have been other issues raised by the community on this forum, but I would be a broken record if I repeated them again. Also please don’t feel I’m attacking you. You’re raising different opinions and challenging what we thing which is good, and encouraging! So long as both sides of this argument are open and understanding to one another.
If you have a dispute you can call 3D hubs in and they can act as moderator… thing is at the end of the day you gotta play the role of a customer… if you get a part in that you specified as needing to be precise and someone send you a WILDLY out of tolerance part… you would not be very happy would you?
I feel like if you have a potential issue with an order its your job to communicate that with the client BEFORE you guys go agree on a print… That said I do understand your concerns but having a guideline you AND client can refer to would be a good thing in the long run.
One of my points though is that until now I’ve just done this personally, why is there suddenly a need for 3D hubs to intervene? And a customer doesn’t need to give ‘wildly’ out of tolerance parts, only 1% off. As some have brought up, unless we as hubs are to now measure every part we make and document it, there is no way to prove otherwise.
Quoting the list above: “FDM parts need to be produced within an accuracy of +/- 1mm or 1% depending on which is greater.” +/- 1MM is BIG… That means that your 20MM calibration cube could be 19 - 21 MM and STILL be a-ok. That is a huge tolerance. Their not asking you to hold .0005" tolerance on a 3" deep hole…
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That’s a tiny tolerance, make a 200mm part and it’s got to be within 2mm?
It’s not about how it comes off your machine, it’s about how it measures when you get it there. Many materials can grow and shrink more than that just from differing moisture levels. Never mind the rest of the stuff I mentioned earlier.
It comes off your machine and measures perfect, gets to the customer and it’s out of tolerance. Now, who is footing the bill and who has to prove it was in spec (and how, since the guidelines are so vague with obviously no proper QA process in place) - guess what, it’s the hub.
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1% for 20mm is 0.2mm (1/5th of 1mm)
1% for 200mm is 2mm (2*1mm)
bye, Tibor
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1% or 1mm maximum. 20mm object= 0.2mm tolerance. 200mm object=1mm tolerance
bye, Tibor
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Georgei
94
Dimensional accuracy: +/- 1mm or 1% depending on which is greater
So
20mm object = +/- 1mm tolerance
200mm object = +/- 2mm tolerance
cobnut
95
@Vienna3DPrint the guidelines say “whichever is greater”, so for a 20mm cube, 1% is 0.2mm, yes, but 1mm is greater so you could print anywhere between a 19.01mm and a 20.99mm cube and still be (just) within the 1mm tolerance for a print that should be 20mm.
The whole sentence says: “FDM parts need to be produced within an accuracy of +/- 1mm or 1% depending on which is greater.”
greater=accuracy
Maybe a native English speaker could formulate a less contradictory sentence.
bye, Tibor
As I mentioned before: greater is misleading, as I don´t think the dimension is meant, but the accuracy.
Robin must reformulate the sentence, as it leaves room for interpretation.
bye, Tibor
Georgei
98
The greater refers to the dimension (i.e. +/- 1mm or 1%) and not the accuracy. It is common statement in engineering at least.
The below text is from the original quidelines draft text from 3DHUBS
FDM parts need to be produced within an accuracy of +/- 1mm or 1% depending on which is greater.
For example, in the case of a 40mm cube, a 1% accuracy requirement would result in a max of 0.4mm deviation. As this is below 1mm, the 1mm is leading and determines the maximum. A printed part of 40.6 x 39.4 x 39.3mm would be acceptable as the deviations are within this 1mm. Printing a cube that is 38.8 x 39.4 x 39.4mm would not pass the dimensional accuracy requirements as the width deviates more than 1 mm.
cobnut
99
@Vienna3DPrint hmm, good point, I’m now wondering if I’ve read it the right way (as a native English speaker!). A better (but not necessarily ideal) sentence would be either of:
“FDM parts need to be produced within an accuracy of +/- 1mm or +/- 1%, whichever is the lesser inaccuracy.”
(so the 20mm cube should be produced to within 0.2mm, because 1% is less inaccurate)
or
“FDM parts need to be produced within an accuracy of +/- 1mm or +/- 1%, whichever is the greater inaccuracy.”
(so the 20mm cube should be produced to within 1mm, because that is the greater inaccuracy)
depending upon which meaning 3DHubs are actually looking for, and the 1% should be +/- as well. @Robin3D ?
edit (just noticed the doc does include examples)
