That’s exactly right, these guidelines are set to that both Hub and customer have default expectations of a 3D print. If a customer needs the parts with higher dimensional accuracy, it should be indicated and this is what we’ll add during the order flow so customers are aware of what they can expect.
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Hi,
Some comments on the guidelines:
1% dimentional accuracy is not good enough for me. I print loudspeaker cabinets at roughly 300mm x 200mm x 300mm scale. 1% would mean that a accuracy of 2.9mm is acceptabe. I cannot load drivers into the cabinets with this level of accuracy and would not be able to rely on prints adhering to these guidlines.
I don’t understand what a layer changing ‘seam’ means. I have received prints where there is a step in the surface and i would suggest that this is not perfect and therefore should not be allowed. I cannot sell products which have a step in the surface and i think this should be included in the guidelines. The guidelines need to have clear definitions (the photos will probably help!)
Disputes were previoulsy on the basis of prints being ‘perfect’. These guidelines seem to water that down in some areas.
I’d also like to suggest some content on infill. Infill has caused me all sorts of problems, not least because it is quite poorly defined. I asked two hubs to print identical stl’s (actually they were mirrored) and without any comms (because i was at this point completely in the dark about the concept of infill) one printed with triple wall thickness and infill of 20% on a 7mm thick enclusure wall (3mm solid - 1mm 20% - 3mm solid), the other printed with 1.2mm wall thickness and 15% infill (1.2mm solid - 4.6mm 20% - 1.2mm solid). One was 40% density, the other nearly 80% density. The difference was huge, and both were within the rules before the guideliness and would be within the rules of these guidelines. As such I think something needs to be included in the guidelines about infill. Or maybe on the ordering page.
In gereral supportive the the initiative.
Thanks
Chris
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.
