Pushing the Limits of 3D Printing: Large Fragile 3D Prints

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We all know that is possible to design and make the otherwise impossible with 3D printing: to 3D print incredibly detailed items that are light as air, with thin wiry structures, multiple internal cavities and complex, interlocking moving parts with minimal clearance.  Although it may be possible to 3D print such items, they do not always survive once they are removed from the 3D printer, cleaned, packed, and shipped around the world.

Shapeways 3D Printed Stag Wireframe

Recently Shapeways community member Dotsan designed an amazing Stag Wire 570mm that used the full size of our largest Nylon (WSF) 3D printer. We did manage to print two of these for Dotsan, but the model was so fine, with 1mm wires for such a large object it failed during printing and broke during post processing, so it took us multiple prints to get it to survive. We then packed it very, very carefully and shipped it to Dotsan with our fingers crossed, hoping that it was not damaged in transport.  

Fortunately, the 3D prints were delivered to Dotsan intact, as he shared in his very impressive unboxing video. Unfortunately, the risks involved in printing, post processing, packaging, and shipping the item are too great and we have asked Dotsan to take the design down from sale on Shapeways to ensure his customers don’t have a negative experience.  This is not something we wanted to do, we struggled and debated internally about the ramifications of this, but in the end we were forced to take this action for a number of reasons, the two main issues are:

  • The cost of such a large, wiry model with very little mass does not match the actual cost of 3D printing, especially as the model is prone to failure at any point along the supply chain so we would have to reprint multiple times. 
  • When a model of this size fails and we need to reprint, it will consume capacity and delay all other models in the queue, especially large ones.

We need to look at how we address the pricing structure to account for large wiry models such as this in the future. We could look at them on a case by case basis, which could slow down the production of large models, lead to rejections after acceptance if they are too fragile and add a degree of unpredictability. Or we could address the pricing structure at Shapeways to better reflect the actual the cost of 3D printing.

At the moment, we only charge for the amount of material used and not the overall size (bounding box) of an object that we 3D print.  The size of an object DOES influence the actual cost of printing.  If we were to bring the bounding box into the pricing equation, it would make some thin, wiry 3D prints more expensive, but it would reduce the cost of many 3D prints that are thicker, with greater density.  Thin wiry models are more prone to print failure, damage during cleaning, post processing and shipping so there is additional cost (and delays) when we need to reprint a model.

We already offer a volume and density discount on Nylon (Strong & Flexible) materials. For models that have greater than 10% density (material volume divided by bounding box volume), after the first 20 cm3, the remaining volume is calculated with a 50% discount. 

Perhaps we need to incorporate the bounding box into the pricing equation on all models to better match the actual cost of 3D printing and incentivize designs that are less fragile and more reliable?

We would love to know your thoughts about bounding box being added to the pricing structure and how it would it change the way you design.

10 comments

  1. David Nichols

    I’m not sure why jumping to “bounding box” as a full or partial replacement of the pricing model is proposed here, when the factors you list as contributing to the costs are not necessarily measurable by looking at the bounding box.

    If anything it seems like a very localized “density” measurement would be more accurate in predicting trouble.

    So the question that I would ask is what other machine measurable characteristics of a model can you use to estimate from an expected cost contribution from:
    -reprinting due to failure unloading the machine
    -reprinting due to handling during post processing
    -reprinting due to damage during packaging and shipment

    I think ultimately if Shapeways is worried that the material volume pricing model is out of whack with the costs then the only way to appropriately adapt it, regardless of newly chosen technique, is to carefully measure the cost to produce each model as a function of its bounding box, volume, localized density, etc, and then back out a regression analysis of those characteristics to see which actually have problematic cost contributions. Measure what Shapeways paid in lost machine time due to reprinting, lost material costs due to post processing failure, etc. And once you have enough data, look at it to see where there are opportunities to better model the cost of producing a print.

    Measure, measure, measure… hopefully you’re doing that already!

    Shapeways’ capability to produce large but sparse models at a reasonable price is a unique and revolutionary capability. I don’t want Shapeways producing these at a loss but I would be very careful not to throttle one of the key differentiators to this service. Thanks.

    David

    1. Duann

      Thanks David,

      You are right, the issue is density but is also tied to the size of prints. We do measure, EVERYTHING…

  2. stannum

    Two questions:

    Were neck and head filled with small items to not waste the inner space so much?

    Why a model with 1mm was allowed to go the printer at all? Your rules say that for 570mm the minimum wall thickness must be 3.42mm.

    1. Anonymous

      What he says..
      All this for a model that breaks the design rules?

  3. Henry Segerman

    Dotsan’s design looks great, but it looks like it might get damaged by a strong gust of wind. I wouldn’t want to be buying or selling something that fragile. No consumer product meant for mounting on a wall would be that fragile, and I would imagine that there could be disappointed customers as a result.

    It sounds from the story that much of the expense involved was in reprinting due to damage. It’s certainly possible to make large, wiry but strong models (I’ve done a few, see http://www.shapeways.com/forum/index.php?t=msg&th=10594&start=0& ). I assume that these didn’t require multiple reprints due to breakages, they seem very sturdy to me. Most of these cost a little under $1000 each, rather than $25 or so. I don’t know if that’s a reasonable price relative to Shapeways’ actual costs for making one of these, but I assume that breakage and the resulting reprinting is not the issue for these models.

    So, I would worry that adding in the bounding box size would bump the price up to the point where it became prohibitive to print anything at these scales. I might even find myself trying to skimp on the thicknesses of the object I want to print to get inside my budget, reducing the price but making it more likely that the thing breaks and requires reprinting!

    Bounding box size plus volume of the model can predict a weak model if the bounding box is big but the volume is tiny. But beyond a certain point, this relationship breaks down.

  4. mkroeker

    Seems to me you guys got carried away by the beauty and challenge of this design,
    so you tried to get it done instead of rejecting it outright. Which probably would have been
    perfect for a single showcase copy – seeing what ridiculous stuff gets built for trade fairs
    sometimes. This beast must have caused internal discussion among the guys responsible
    for model checking and production planning in any case, so why don’t you just reroute such
    rare white elephants (sorry, stags) through customer service, explaining that you cannot
    accept them for the automatically quoted price (or will only do it once) ?

  5. Alex Delderfield (ADEdge)

    Yikes, what a nightmare model to print!

    Good to see Shapeways actually went to the effort of making it work, but I can certainly see why youre against selling them in the shop. Certainly a model at the extreme end of the scale when it comes to being so large with such thin structure. Not sure how much it would have effected the cost of the model at that size, but if I were the designer I would have attempted it at a 2mm thickness. Probably would have worked out much stronger and could have been potentially reproduced to order.

  6. Michiel Cornelissen

    In the long run, I think that the closer SW prices match the real cost of printing, the better it is for everybody; especially if the system is transparent enough so that one can design towards it.
    However, if changes in the pricing structure are made, it might be good to think about a transitional period (a year?), perhaps only for existing models, so that we don’t get hit to hard for having designed for the previous system.

    1. Duann

      Hey Michiel,
      I think you will find many of your designs might actually be cheaper if we were to bring model density into the material pricing equation. As Stannum noted we do have guidelines about thickening minimum wires as size increases but this is a little complex to check. We want to make it both fair and easy for everyone. I doubt that we would ‘grandfather’ all existing designs but we will look at this carefully to ensure any transition needed is as smooth as possiible.

  7. Alan Harrison

    I think models like this are great, they push the boundaries of what is possible. Unfortunately with manufacturing, even with additive manufacturing, there is going to be problems that need to be accounted for and designed around. I would like to see this model for sale to the general public, this is what shapeways is best at, creating products that can’t be made by other means. I would find trying to design a manufacturing solution for this quite interesting. Maybe a model like this would better with some kind of frame to protect it through production and shipping. Support wires that would need to be cut away when received by the customer. Of course designing a solution would be expensive and time consuming, but something like this is really food for thought. I hope to see this model for sale at some point in the future.

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