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Hollowing out made no price difference. [message #64892] Tue, 26 March 2013 12:49 UTC Go to next message
avatar 3dinLeiden  is currently offline 3dinLeiden
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Hi everyone, (project game pieces)

I have uploaded a model. It passed auto check, price $80.30. I need 2 sets to play test it, so I thought I would try hollowing out the bases.
That uploaded ok and the auto 3d-rotate model-viewer shows the hollowed out bases.

I think this should be about at least 1/5 reduction in material . The price calc show the same.

I am using file format *.obj in 3ds 9. Boolean subtraction. I noticed the Oriented Bounds Vol had reduced, see below;

V1: un-hollowed :price $80.30.

Oriented Bounds (used for determining printability)
In: 7.4 w x 1.5 d x 3.7 h
Cm: 18.9 w x 3.9 d x 9.4 h
Vol: 92.58 cm³

V2: hollowed bases :price $80.30.

Oriented Bounds (used for determining printability)
In: 7.4 w x 1.5 d x 3.7 h
Cm: 18.9 w x 3.9 d x 9.4 h
Vol: 56.28 cm³

Any ideas about this?

Thanks,
3dinLeiden
Re: Hollowing out made no price difference. [message #64894 is a reply to message #64892 ] Tue, 26 March 2013 12:55 UTC Go to previous messageGo to next message
avatar virtox  is currently offline virtox
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That seems very strange, which material are you working with?


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Re: Hollowing out made no price difference. [message #64897 is a reply to message #64894 ] Tue, 26 March 2013 13:13 UTC Go to previous messageGo to next message
avatar 3dinLeiden  is currently offline 3dinLeiden
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White Strong & Flexible

I am guessing that there is an issue with the 3ds9 boolean in my model, and that the shapeways rendering anim recognises it, but the algoritm for price doesn't.

...but then the volume has changed.

Is this the volume that is proportional to the price?
Oriented Bounds (used for determining printability)
In: 7.4 w x 1.5 d x 3.7 h
Cm: 18.9 w x 3.9 d x 9.4 h
Vol: 56.28 cm³

[Updated on: Tue, 26 March 2013 13:14 UTC]

Re: Hollowing out made no price difference. [message #64898 is a reply to message #64897 ] Tue, 26 March 2013 13:23 UTC Go to previous messageGo to next message
avatar virtox  is currently offline virtox
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Should the boolean made such a mess of the mesh that the upload at filter at Shapeways would need to fix it, it would show that in the previews as well.

But as you note the volume does change so, either the price is delayed or broken?

The pricing has some linear elements, but there is also a density discount. But would be very coincidental to hit the exact same price;-)
Are the prices for the other materials identical as well?


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Re: Hollowing out made no price difference. [message #64899 is a reply to message #64897 ] Tue, 26 March 2013 13:26 UTC Go to previous messageGo to next message
avatar stonysmith  is currently offline stonysmith
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We'd need to see the model to try to offer any suggestions..

Can you upload a copy of your model here in the forum, and/or make the model in your shop public?
If you'd rather keep the model private, you could PM a copy of it to me.

Most such cases are caused by bad boolean operations, but yes, if the volume changed, then the price should have also.


Patience, Persistance, Politeness - the 3Ps will help us get us to Perfect Printed Products
Re: Hollowing out made no price difference. [message #64900 is a reply to message #64898 ] Tue, 26 March 2013 13:30 UTC Go to previous messageGo to next message
avatar virtox  is currently offline virtox
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Hmm, but density discount is something to take into account as your models are just below and just above the threshold of 10%

Quote:

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.


So the first model is

Cm: 18.9 w x 3.9 d x 9.4 h
Vol: 92.58 cm³

92.58/(18.9*3.9*3.9)=13.36% density

Meaning the price will be
1.50 + 20*1.40 + 72.58*0.70 = 80.306


the second is
Cm: 18.9 w x 3.9 d x 9.4 h
Vol: 56.28 cm³
56.28/(18.9*3.9*3.9) =8.12%

1.50 + 56.28*1.40 = 80.292


WOW, you did hit the exact sweet spot Wink


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Re: Hollowing out made no price difference. [message #64901 is a reply to message #64898 ] Tue, 26 March 2013 13:43 UTC Go to previous messageGo to next message
avatar 3dinLeiden  is currently offline 3dinLeiden
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Good point virtox, only the price of top two materials are the same but the rest look to have nearly halved, in line with the volume reduction.
These are only prototype pieces and I will need two sets to playtest, so I am trying to keep the price low.

...of these, sandstone now looks the cheapest. 72.44 reduced to 45.21

However the pieces have lids which I want to clip onto the bottom part, like a russian doll.
I am not sure sandstone will be good for this, perhaps thin walls (approx 4m) are likely to crack?

How does this affect peoples opinions of the issue (White Strong & Flexible + Black Strong & Flexible, no price change)



Thanks for the quick responses people.
Re: Hollowing out made no price difference. [message #64903 is a reply to message #64901 ] Tue, 26 March 2013 13:51 UTC Go to previous messageGo to next message
avatar 3dinLeiden  is currently offline 3dinLeiden
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Hi virtox, (I posted my last reply befoe getting your 'density discount' reply so maybe this one will also come through after a new one)

I was not aware of that discount. I think i can greatly reduce the bounding box but am not sure how the print works.
I can put the lids (nearly) on the pieces... Say hovering 5mm above them but with the pieces inside the hollow lids?

If I reduce the boundary box, that will increase the density, so I'm not clear on how that discount works.
Re: Hollowing out made no price difference. [message #64908 is a reply to message #64903 ] Tue, 26 March 2013 14:40 UTC Go to previous messageGo to next message
avatar 3dinLeiden  is currently offline 3dinLeiden
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The above approach worked. Placing the pieces inside their lids to reduce the bounding box triggered the aforementioned discount ( presumably ).
The White Strong & Flexible new price down to $ 54.90.

I am new to this, but I don't think shapeways have been good at publising this factor, as most of the things I have read are indicating that the bounding box makes zero difference to price. Also I still am not sure why the other prices reduced previously and the White/black Strong & Flexible didn't, guess only they get density discount.

If I have now triggered a density price reduction... is it a flat reduction once I have gone under a 10% density, so packing them in futher I think will not get any further price reduction. I plan to try another more packed-in to check if it will reduce further.

Thanks for the advice, perhap someone can summarise what they think its going on with this as it has left me still a little confused.

[Updated on: Wed, 27 March 2013 09:51 UTC]

Re: Hollowing out made no price difference. [message #65055 is a reply to message #64908 ] Thu, 28 March 2013 10:37 UTC Go to previous messageGo to next message
avatar bartv  is currently offline bartv
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Hi 3dinLeiden,

Quote:

I am new to this, but I don't think shapeways have been good at publising this factor, as most of the things I have read are indicating that the bounding box makes zero difference to price.


You're absolutely right, we need to promote this more. As higher density models are actually more efficient for us to produce, this would be a win for us, too.

Thanks!

Bart


Community Manager Europe | Shapeways
Re: Hollowing out made no price difference. [message #65061 is a reply to message #64908 ] Thu, 28 March 2013 12:33 UTC Go to previous message
avatar virtox  is currently offline virtox
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To be clear, the density discount applies when you go above 10%.
Once you get the discount, packing further will make no difference.

This is for basic black and white nylon:
If the volume/(optimal bounding box) >10% and model has more than 20cm3 volume:
the first 20cm3 will cost $1.40 all cm3 above will cost you $0.70

If you drop below 10% you pay $1.40 for all cm3
So for some models it is actually cheaper to add some waste material in the model to increase the density :-S
This is a side effect of the current implementation by Shapeways.


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