Price confusion

Hi, I uploaded a model and it came to €120.00

I altered the model to make the walls thinner and reduce the amount of material needed and uploaded it again and the price was €191.00 in the same material.

I'm very confused.

If that was WSF as the material, there's a volume discount once the volume is above 20cc and the density is above 10%. See, WSF material page for more info. Otherwise, it could be the wrong units of measurement selected at upload.

I've uploaded about 4 different versions of the same model each one theoretically smaller in volume in the last and the one I thought was smallest was 191 euros and one of the larger volume ones 121 euros and all of them are are coming in at wildly differing prices in between. 60 euros is a lot of error margin.

Generally there are no pricing errors. It may be that the method you've used to hollow the model has caused Shapeways automated software (Mesh Medic) to merge shell differently to how you expected, or there may be a number of other reasons that the volume of the model is different to what you were expecting.

A great free tool for helping to get the bottom of these kind of issues is NetFabb Studio Basic - it will show the dimensions and volume of a model.

If you get real stuck, send me a PM with the model file & I'll take a look.

Paul

Netfabthingy not helping. When I click the red cross it destroys my model.

Not happy about Shapeways random charge structure. Maybe I should try another company.

Your best bet at this moment is PM the file to stop4stuff (or I) and we'll be glad to take a look.

It's very kind of you but there's a confidentiality issue and I don't know who you are.

Shapeways should explain this, it's their problem.

I'll try iMaterialise if Shapeways can't be bothered, which currently seems to be the case.
When I emailed I got a very terse and unhelpful reply.

Thank you for offering to help though, I posted in case it was something obvious but I guess not many people upload the same file with minor changes to assess how Shapeways deal with it.

It is not Shapeways problem, it is a structural issue with your model. Most likely caused by shells that share geometry. What happens is that the shared geometry confuses Shapeways MeshMedic and NetFabb, the software doesn't know what your intended outer surface is and will do the best it can to combine the shells into one, which in your case 'destroys' the model.

I have no problem in signing any NDA, you can email me direct, paul[at]stop4stuff[dot]com.

Paul

p.s. you'll most likely get the same issues with any other 3D print service too

I have no problem believing it's a problem with my model., I just think a €90 margin for error is pretty steep especially when Shapeway's upload hasn't said there's anything wrong with my model.

If the software creates a different outer shell with each upload, the volume changes and so will the price.

By going on double the price? Something that should be made clear up front I think.

It seems that you missed the point.

Pricing is calculated from the volume of the model (or surface area for ceramics.

Your model is structurally incorrect.

Shapeways MeshMedic software checks the integrity of your model whilst at the same time merging any multiple shells.

If the shells share geometry MeshMedic may delete some.

If shells are deleted the volume changes.

If the volume changes, so does the price.

If you halve the size of a cube, the volume is 1/8th of the original. The price would be more-or-less 1/8th too.

I feel that YOU are missing the point.

This information should be given up front before ordering, not vouchsafed on a forum in the dead of night along with the fact that it can change the price of your model by going on double.

Thank you for your help. Shapeways didn't tell me this at all when I emailed them.

I give up

My feelings exactly.
It's taken a lot of wasted time to figure out whats going on and you've been very helpful.

Thank you.

I think that you probably have not understood how the density discount works yet! It is something introduced in the pricing structure of WSF to make larger models more affordable.

If your model has a density greater than 10% (the volume of the model divided by the volume of the bounding box is greater than 0.1) and volume greater than 20cc it will receive a discount: instead of the price being 1.5+1.4*volume, it will become 15.5 + 0.7*volume.

The reason your model jumped up in price when you reduced the volume, is that the density got below the magical 10%, and then the more expensive pricing model was applied.

With the density discount applicable, a 190cc model will cost $150 = €120. (ex. VAT)
Without the density discount applicable, a 135cc model will cost $240 = €190.
If your model had a bounding box of 2000cc in the case of 190cc volume it would have gotten the discount, but in the case of 135cc volume it would not have gotten it.

So you can see that sometimes a model with less volume will cost more than one with more volume. This is probably what is causing your confusion.

Shapeways are very helpful and good at what they do, provide a 3D print service, however most of the staff aren't conversant with the trials & tribulations of difficulties with model issues, hence these forums where designers & modellers like me, stony and countless others are more than happy to help other people find their feet.

I hope you get things sorted.
Paul