[GTA04] When is the next and more powerful openmoko releasing
Dr. H. Nikolaus Schaller
hns at goldelico.com
Mon Oct 25 20:55:53 CEST 2010
>> Well, we have anlysed approx. 5 or 6 different methods and none was
>> inexpensive for low volumes. The only one that came down below 50 EUR per
>> case is injection moulding.
>> But I would be happy if you can guide the GTA04 to a different approach.
> It would be good if you could share the results of your research so other open
> hardware projects can get an idea of what a custom case might cost, and see
> how different manufacturing methods compare. It might also stop us suggesting
> things you've already investigated an rejected! Also exactly how low is low
> volume? Given the differences in setup costs for different manufacturing
> methods it could make a huge difference to the unit cost.
All methods have setup cost (once) and cost per unit. Some methods have to repeat
setup cost avery n units (e.g. silicon moulds made from Stereolitography).
Our results so far (I can't share all of them):
STL + Silicone moulds: 2000 EUR setup + 50 EUR each every 100 units
Injection Moulds: 25000 EUR setup + 20 EUR per unit
3D-Printing: no setup, 400 EUR every unit (quality doubtful)
Milling from ABS block: no setup, 500 EUR every unit
So 1-10 units does not come below 250 EUR. 100 units may come to 70 EUR.
1000 units to 45 EUR. 10k to 22.50 EUR. You see the volume effect and
clear preference of injection moulds. Which also give best quality...
All these are lower estimates on industrial (not hobbyist) quality and based on 3D CAD files
from Openmoko and does not include control of the process (someone must spend time
to initiate and keep it running). Experience shows that real project cost is twice as high
as the estimate...
>> I agree that just suspecting that it exists is not enough .
>> We have already spent several months discussing and asking for quotes and
>> everyone can make such things. Technically. But if we ask for cost we are
>> either beyond 100 EUR per piece in low quantities. Or there is need for
>> some upfront investment that only pays off if we make more than around
>> 1000 units.
> If you've already investigated laser cutting I'll stop now. I suggested it
> because the setup cost is very low relative to other methods, and I've seen a
> couple of one-off cases made that way. It also lends itself to manufacture at
> someone's local workshop, including laser-etched personalisation. I'm assuming
> people will be up for a bit of self-assembly here.
Laser cutting was not yet amongst the production methods. Please try to get
an estimate for setup cost (e.g. converting CAD data) and unit cost (material
plus machine operation time).
>> I think we all will be very happy if we finally find another method that
>> does not need big VC money, i.e. can be done by joining all forces of our
>> Well, an alternative approach could be to open a funds for a new injection
>> mould. I.e. a "Openmoko Case Production Foundation" (or German e.V.).
>> Everyone who gives some money for the funds can buy cases at a reduced
>> rate. And everyone can buy a case. An injection mould costs somewhere
>> around 20-100 k EUR. So if we get 300 community members to donate 100 EUR
>> into the funds...
> That's certainly worth a look, especially if with a case design that would
> last for several generations of board.
And potentially several different designs for the same board.
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