Wrong volume calculation and prices ?

Discussion in 'Bug Reporting' started by Strangefate, May 14, 2013.

  1. Strangefate
    Strangefate New Member
    Basically, I have a model that shapeways tells me is $88.04 which compared to similar uploads seemed to much:
    http://www.shapeways.com/model/1095915/test02.html?li=my-mod els&key=d2f2bc0ab3c0f97e4019d97a5c6cbbca

    So as part of some testing I broke it down into 2 models:
    one is listed for $52.02: http://www.shapeways.com/model/1095154/new-52-powergirl.html ?li=my-models&key=fb60530e0271b35c6947ecd2152c6023
    the other part for $18.01: http://www.shapeways.com/model/1095222/test.html?li=my-model s&key=dca43dc925fa57c29d9f16fa2613f91e

    That's about $18 difference, which is a lot. The volume should calculated based on the actual material used not on the bounding box of the model or something like that ?

    After reading up here I guess the problem is the volume calculation, but all the posts I found were from around 2009.

    Is there a way around this, I'd rather not sell my model in 2 pieces and I'd love to not distrust shapeways everytime I upload a new model.

    Last edited: May 14, 2013
  2. AmLachDesigns
    AmLachDesigns Well-Known Member
    For WSF:

    Handling Fee Per Model: White: $1.50, Black $1.75, Polished: $2.00, Dyed: $2.25

    Price Per cm3: White: $1.40, Black: $1.75, Polished: $1.50, Dyed: $1.50

    For models that are greater than 10% dense (material volume divided by bounding box volume), after the first 20cm3, the remaining volume is calculated with a 50% discount.

    If you go to your model and look at it in Edit mode then it should tell you the volume of material and the dimensions of the Oriented Bounding Box. If you calculate the volume of this OBB and divide the actual volume by the OBB volume this will tell you whether or not your model qualifies for the volume discount.

    Using all the above (and a spreadsheet!) you should be able to calculate the theoretical cost of each of your models.

    What you have already stated does not seem to make sense, as it seems to me that the single model should always be cheaper than the twin models:
    a) Because you are saving the handling fee of one model;
    b) Because if you qualify for the volume discount, then in the twin model case you will have to pay full rate for up to 20cm3 more than in the other case;

    Perhaps the cape is the problem - maybe it is increasing the OBB to the point that you get no discount. As a test, you could lay it flat underneath the other components (I understand that you would not want to do this for orientation reasons, but just for a test).
  3. Strangefate
    Strangefate New Member
    I'll try that, thanks.

    I've had this before, while I was uploading revisions of a model, one revision was suddenly $10 more, without any visible reasons. I checked the mesh to make sure I didn't forget to export one of the cavities or anything, but everything seemed fine. The next model revision got the correct price again.
  4. Strangefate
    Strangefate New Member
    Moving the cape didn't help, exact same price. I'll re-export all the parts later, maybe that will do something again.

  5. AmLachDesigns
    AmLachDesigns Well-Known Member
    What are the volumes of the first three models?
  6. Strangefate
    Strangefate New Member
    57.36 cm³ for the complete one, which would add up to the $88

    46.69 cm³ for the body... and I think this is the problem, it adds up to $70 (with WSF polished) but shapeways says it's $52... which should be correct as the other figures and test figures print always for that price range (they're always hollow).

    10.67 cm³ for the cape which adds to the correct price too.

    I'm hoping a re-export will fix it.
    Last edited: May 14, 2013
  7. AmLachDesigns
    AmLachDesigns Well-Known Member

    I think SW has calculated it correctly.

    The complete model if we assume no discount is:
    2 + 57.36*1.5 = 88.04

    The cape (plus rods):
    2 + 10.67*1.5 = 18.01

    The body:
    2 + 46.69*1.5 = 72.04


    The body (if we assume you are in the 'discount zone'):

    handling fee + 20cm3 at full rate + the rest of the volume at half rate
    2 + 20*1.5 + 26.69*0.75 = 52.02

    So for the complete model as is you are getting no discount. If you re-jig the layout of your components so that the whole thing is more compact, you should be able to get the model for:

    2 + 20*1.5 + 37.36*0.75 = 60.02

    i.e. less even than the 2 separate models, which is as it should be, as you are only paying full rate for the first 20cm3.

    Check these figures (!) but I think they are right.
  8. Strangefate
    Strangefate New Member
    Interesting, never paid much attention to the discount part, didn't think it would affect me that much...

    I'll rearrange things as best as possible and see what I get.

    And you sir, should get a medal, thanks a lot :)

  9. AmLachDesigns
    AmLachDesigns Well-Known Member
    No prob, it was fun...
  10. Strangefate
    Strangefate New Member
    got it!

    it comes exactly to your 60.02 :)
  11. AmLachDesigns
    AmLachDesigns Well-Known Member
    Nice one.

    It's good to save some cash.

    I think your model is great, by the way. Good work!
  12. Strangefate
    Strangefate New Member

    thanks a lot :)
  13. stop4stuff
    stop4stuff Well-Known Member
    And don't forget, comparing a model to another on Shapeways is no definitve way to work out a model's cost as there's no idea of what markup has been added or if a model has been optimised for material wall thickness ;)