Openmoko Beagle Hybrid

Dr. H. Nikolaus Schaller hns at goldelico.com
Mon May 17 07:06:45 CEST 2010


The problem is not technology or DIY capabilities, but cost.

What we want to have is a nice case achievable for everybody, not only  
the enthusiast who wants to spend time and money for experimenting  
with DIY hardware or commercial FDM.

So the question is how much does a SW developer want to pay to get HW  
+ Case? Let's say 50 EUR per plastic case.

FDM is at least 200 EUR (that is what we got as a quotation from the  
rapid-prototyping shops for a simple part and not the whole case). Or  
700 EUR for a Cupcake. Or 5k for a protomold made thing. Or 10-20k EUR  
for a 3D printer. A full freerunner case consists of 6 plastic parts  
(incl. 2 buttons).

The other side is expectation of quality/robustness. I have been told  
by experts who own a RepRap/CupCake that the precision is not good  
enough to reproduce a Freerunner case (wall thickness 0.5mm).


Am 17.05.2010 um 06:03 schrieb Shawn Rutledge:

> On Tue, May 11, 2010 at 12:56 AM, Dr. H. Nikolaus Schaller
> <hns at computer.org> wrote:
>> has fixed dimensions) and we can't afford to build plastic injection
>> moulds (if someone has an idea how to reduce cost this is very
>> welcome). So the easiest solution was to combine what we have: a  
>> given
>> Beagleboard and the Freerunner case.
>
> Personally I don't see what the big deal is with mold-making.  Anybody
> could start a business doing that if it's so lucrative: get a Harbor
> Freight or other cheap milling machine and some blocks of aluminum,
> and develop the skill to do sufficiently accurate machining.  (I have
> tried a little milling but my skill level definitely needs a lot of
> improvement; maybe it will if I ever get around to doing enough of
> it.)  Of course CNC would be nice, but again, what's the big deal...3
> steppers or servo motors and a controller...  As someone else
> mentioned the Chinese obviously aren't having too much trouble with
> mold-making.

>
> It's also within the realm of possibility to make your own injection
> molding machine.  There is a book (Gingery) about how to do that, but
> there is nothing too exotic in that book either... it's just a heated
> cylinder and piston arrangement with a lever to apply the pressure.
> Hot plastic comes squirting out, and you have your mold clamped in
> place to receive it.
>
> Alternatives include building a RepRap, making the plastic parts
> directly, and putting up with rough, inaccurate results; buying a
> better rapid prototyping machine (FDM type or laser sintering or the
> type that builds up parts from thin laminates); or directly
> CNC-milling the cases (you could even use wood then).  As a DIY/hacker
> type thing rather than commercial, it might fly.  Maybe try to get a
> story in Make Magazine because there seems to be a trendy new crowd of
> DIY/hacker types nowadays, who weren't around a couple years ago.
>
> Or get it made at one of the rapid-prototyping shops.  For every type
> of RP technology there are multiple shops doing on-demand prototypes.
>
> In any event, the case design could be posted on
>
> http://www.thingiverse.com/
>
> and maybe someone who has a RepRap or similar can try to make a  
> prototype.
>
> There was a design contest going on but I guess the time has passed:
>
> http://blog.makezine.com/archive/2010/04/makerbot_giveaway.html
>
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