It's That Time Again To Figure Out How Prices Are Calculated!

Discussion in 'General Discussion' started by DoctorOctoroc, Aug 9, 2018.

  1. MrNibbles
    MrNibbles Well-Known Member
    BTW, the 1cm cube yields a quoted price of $1.82. But what should it be? The old formula:
    $1.50 base price plus $0.28 per cm^3 of material and $0.21 per cm^3 of machine space.

    Material space would be 1cm^3 and machine space would be about 1.728cm^3 so
    estimated price (wsf) = $1.50 + 0.28 + 1.728(0.21) = $2.14.

    There appears to be a pricing error that is advantageous to the customer when this error happens, assuming the pricing formula has not changed since earlier in the year.
  2. MrNibbles
    MrNibbles Well-Known Member
    I was only able to see this machine space anomaly for a 10x10x10mm cube. Make the cube 1mm larger or smaller on all sides and machine space calculation seems reasonable. Squish the 10x10x10mm cube into a 10x20x5mm bar having the same volume and everything seems ok. Very strange indeed!
  3. freescape_8
    freescape_8 Member
    So I've been busy with school the last few months, and have somehow missed all the news on this.
    I just had a model rejected that's been printing fine up until last week. The sprues were apparently 0.007mm too small to print, so I have to update the model (according to their email to me, and my limited access to printing).
    Strangely though, their new interface where I would normally click "update" doesn't show this button anymore, but instead sits there loading for hours, never finishing, and always telling me:
    So I am unable to print the old one, unable to update the part, and to top it off...
    I uploaded the new version only to find it's 43% more costly, at 8.50 USD.

    This all makes no sense to me. I had already replied to my customer by saying the price might change by a couple cents because I have to add material, but now it's changed by a couple dollars, and I have to tell them there's nothing I can do.
    FinishingTouch likes this.
  4. This happened to me too. I printed a model and it was perfect, better than I expected. I didn't print a mirror copy of it and when I ordered it last weekend I received a message that parts of it were too small to print. I sent a photograph of the earlier print, but it was still not approved for printing. I was told I could not have it printed as is. I had to fix the model myself or someone on the design team could fix it. I didn't want it fixed. It was wonderful before.

    I know they are changing over to offer color prints for different materials, but this should not have happened. I am thinking this may cause many models offered for sale to become failed prints when someone orders it. Whoever decided to change over the machines before Christmas made a grave error. Not only am I not getting my mirrored model, but the rest of my order won't ship until Christmas Eve! I almost bought my daughter a Christmas present from another shop and I am now really glad I did not.
  5. Wizmacnz
    Wizmacnz Member
    I had a model for a customers order rejected for weak geometry. The weak piece of geometry actually being a 1.4mm diameter WSF loop that passes through each piece to keep the parts together, added back when Shapeways added a per part charge. Anyone that knows their WSF would know that 1,4mm diameter of the material is really strong. Shapeways have decided however that this is a sprue and needs to be 2mm in diameter. Anyway the updated model was nearly twice the price of the original.

    I read an old comparison review of Shapeways v a competing 3D printing bureau ( that ends with "eo") that concluded that the competitor had a faster turn around but was twice the price, I submitted the updated model to the competitor to get comparison of current prices and their price was 50% lower than Shapeways. Shapeways had better know what they're doing or they are going to lose a lot of business.
    FinishingTouch likes this.
  6. DoctorOctoroc
    DoctorOctoroc Well-Known Member
    yeah, I've always gone with a 2mm sprue but the dramatic price increase is most likely due to the new pricing structure they're rolling out as I can't imagine a little extra material adding that much cost!
  7. MrNibbles
    MrNibbles Well-Known Member
    2mm has been the rule for a year or two now although I'm not sure if it's explicitly documented anywhere. It has however been mentioned in the forum every once in a while when people get rejections for this. I now use 2.1mm diameter if possible just to avoid any possible quibbling with the checkers.

    The biggest SLS plastic price changes seem to be for smaller models due to the new minimum part prices. For example in plain wsf it's now $5 up from $1.50. Going forward it probably makes more sense to loop as many parts as possible to get close to the $5 minimum production price before adding a markup. That lets the customer get the most bang for their buck. Larger items don't seem to be affected as much. I've already modified some models to be connected in some way to minimize parts cost plus shaved off material to reduce material cost. The revisions ended up being cheaper than before. But there's no way I'm going to muck around with changing things in the system until they stabilize it(?) after the holiday season. For materials like HP plastic it also makes more financial sense to have things fabricated at competitors since the costs here for that material are in crazy town. I assume those prices will equilibrate due to competition in the future.
  8. Wizmacnz
    Wizmacnz Member

    Well my 1.4mm loop was made before the 2mm sprue rule came in. Anyway it's not really a sprue because nothing attaches to it. The extra cost is definitely because of the new pricing structure.

    I don't mind price increases in themselves. (e.g. we've had to increase the cost of FUD by 10%). It's changes in the cost structure that can be devastating. I design things that have to compete with traditionally made items, or they wont sell. When you create a design that is optimised to suit pricing structures to end up with a viable commercial product, and then the rules are changed overnight making your product commercially nonviable one can't help becoming somewhat annoyed. This has happened to me now twice with Shapeways.
  9. DoctorOctoroc
    DoctorOctoroc Well-Known Member
    Yeah, I meant to say loop! Although it applies to sprues as well. Pretty much any long thin rod-type geometry will always be minimum of 2mm for me unless the design demands it be smaller (then other precautions are taken).
  10. DoctorOctoroc
    DoctorOctoroc Well-Known Member
    Not sure if this was covered elsewhere but given I haven't been using Shapeways much for printing over the past few months (hell hath no fury like a designer scorned) and I'm just jumping back in to print some stuff for myself, I uploaded a two-part model with the parts in two different positions and got a price difference which leads me to believe they either changed the way they calculate machine space or are integrating bounding box dimensions again.

    Here's my initial upload with the shells simply moved apart from each other:


    And here it is again with the top half moved below the bottom so the open areas are facing away from each other:


    So my assessment is that either the machine space is calculated with all parts in multipart models considered as one (they used to calculate them separately) or the bounding box being larger in the first file is the culprit.
    FinishingTouch likes this.
  11. DoctorOctoroc
    DoctorOctoroc Well-Known Member
    Another thing I noticed (not price related directly but still relevant) is that the machine space viewer no longer allows 3d rotation so you're stuck with a top view (at least it's a top view in my case) with limited information. Not sure why they changed this but hey, more lack of transparency and information is the Shapeways MO these days!


    Although, with the slits in the bottom of the bottom half of the case (bottom half above the top half as in my second example in my last post), you can see blue beyond those slits which means machine space between these parts is being considered even though they're only 1 mm apart. If the machine space was being calculate as a whole, as I previously suspected, then we shouldn't see any machine space visualization beyond those slits. This indicates that bounding box is the difference between the two examples I previously gave.