[Arm-netbook] Crowsupply update

Luke Kenneth Casson Leighton lkcl at lkcl.net
Mon Jan 8 10:06:18 GMT 2018


On Mon, Jan 8, 2018 at 9:32 AM, Hrvoje Lasic <lasich at gmail.com> wrote:
> agree on your points.
>
> did you ever think about in investing in small PNP machine (or just small
> oven plus some hand tools), like being able to produce small batch in house
> and test it qucikly?

 yehyeh, i did - at one point.  although mike only charges abouuut...
USD $300-400 for assembly.    plus... i need to have a stable base
otherwise i am disassembling equipment and shipping it overseas.

 last year i borrowed someone's equipment, i managed to do two of the
RK3288 boards.  RAM ICs $12 each (QTY 4 so that's... $48 in RAM
ICs...), 650-pin 0.5mm pitch BGA processor $12.... you get that wrong
it's f*****g expensive.

 by contrast whomever mike uses, apart from not filling in the huge
3mm hole under the AXP209 (i've now changed that to a hatch-pattern of
about 15 small vias), i haven't actually had a board failure except
where the USB-OTG and Micro-HDMI connectors had to be hand-soldered.

> do you have any idea how reliable www.openpnp.org project is currently, for
> example to meet your specs on board with soem available hardware?

i did investigate openpnp - the critical thing if you are going to
make one of those is, the rod across to the other side to keep the 2
belts in sync is **NOT** optional.  the distance (span) is too great
(600mm) for a single belt to reliablly keep the head position (H
style) steady by driving only ONE side of the horizontal part of the
"H".  you MUST put the rod across so that the motor drives BOTH sides
of the horizontal cross bar EQUALLY.

 here's the thing: if i was intending to manufacture boards "from
home", no problem.  set up a nice business, stay in one plaaaace,
become a home-grown electronics factory, maybe in 10 years have a nice
retirement fund.   it's a nice thought, isn't it? :)  but i'm not
going there... that's not my life's purpose.

l.



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