[GTA04] When is the next and more powerful openmoko releasing
Dr. H. Nikolaus Schaller
hns at goldelico.com
Sat Oct 23 17:05:54 CEST 2010
Am 23.10.2010 um 15:40 schrieb Al Johnson:
> On Friday 22 October 2010, Dr. H. Nikolaus Schaller wrote:
>> Am 22.10.2010 um 02:17 schrieb Al Johnson:
>>> On Friday 22 October 2010, EdorFaus wrote:
>>>> On 10/21/2010 07:59 PM, Alfa21 wrote:
>>>>> you should try 3d print like this:
>>>>> made in ABS which is a good plastic and up to 0.01 inches resolution
>>>> Unfortunately, that's not quite good enough (different units).
>>>> 0.01 inches = 0.254 mm, which is 2.54 times the required size:
>>>> On 10/21/2010 07:32 PM, Dr. H. Nikolaus Schaller wrote:
>>>>> the required precision (0.1 mm, 0.5 mm wall thickness, etc.)
>>>> 0.1 mm is approximately 0.0039 inches.
>>>> I have a question, though - is this precision required for making *any*
>>>> well-working case design (due to the electronics etc.), or is it just
>>>> for making more of the current case design?
>>>> If it's the latter, it would be possible to create a new case design
>>>> that would be easier to get manufactured...
>>> The electronics don't need much precision in the case design. Cases that
>>> clip together firmly and securely do need precision though, and that's
>>> true of the current design. An alternative design needing less precision
>>> is possible, especially if we accept things being screwed together.
>> Generally yes. If we sacrifice quality, ergonomics, and size, we can
>> find simpler and less expensive case constructions.
> I'm sure we can find alternative case construction methods that don't
> sacrifice much in any of those departments. They just won't be methods used in
> the mass market because they don't scale up to those production volumes, just
> as their methods don't scale down to ours. The pcb might need some design
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
But I would be happy if you can guide the GTA04 to a different approach.
> elements suited to a different method of mounting than the current 'clip it
> into the injection moulding' variety, but this is for future generations not
> the current pcb.
Well, the current board is really mounted by 2 torx screws and the connectors
which fit into holes on the sides. The hooks and clips are not really necessary,
which allows for a lot of simplifications. This is where some of us are currently
working on to get the plastics produceable by a RepRap.
>> One aspect to keep in mind for precision are the push-buttons (AUX and
>> Power). The buttons  are specified for a "Travel 0.3 mm +0.1 –0.2 mm".
>> I.e. if we don't want that the buttons get stuck we come to this 0.1mm
>> precision. We have experienced the same with the PCB design where the
>> position of the buttons must be within these 0.1mm...
> That doesn't mean the case needs that tolerance though. It just means the end
> of the actuator needs to stick over the edge of the pcb by the right amount to
> be operable. The external button can be lightly spring to take up the
> tolerance, or rest slightly clear of the button actuator. Alternative switch
If I understand correctly, then the button would not fit smoothly into the case.
It may stand out (or in) so it either gets trapped in the gauze of your trouser
pockets, or you need long fingernails to press it.
> types are an option for future designs, including a change to capacitive
> sensors as provided for by the v2 nav board.
Not completely. The power button must be a mechanical button to wake up the
processor from deep sleep. Or we drain the battery for a always-powered sensor chip.
And, I am not sure if a sensor contact is safe enough for a smartphone in a pocket.
>> The same is with mounting the display. If that is not precise enough, touch
>> operation will be deteriorated.
> Can you elaborate? There may be ways around this one too.
The main thing is that the display bezel must be plane. Otherwise it may
press on the display (touch) at one end and increase the risk of breaking
the display glass. Or you get dust inside the device.
On the other hand we know that the bezel of the Freerunner is already too thick.
I.e. for better operation it should be much thinner. But still stable.
Well, all this can be improved by changing the construction.
>> So if we reduce precision of the case production process, the buttons
>> become larger and finally, the phone is more a brick than a handheld phone
>> Personally, I am in favour of high-end high-quality design (like the
>> iPhone) even if it costs money. But it should never cost freedom and
> high quality design doesn't have to be expensive to manufacture. I suspect
> something attractive could be made in low volume at a reasonable price using
> laser cut plastics. I'll try to ask the local cutters about their precision
> and cut thickness in different materials.
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.
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 community.
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...
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