[Arm-netbook] On (potentially not) 3D printing laptop case parts

Luke Kenneth Casson Leighton lkcl at lkcl.net
Thu May 25 01:50:40 BST 2017

On Thu, May 25, 2017 at 1:33 AM, Forest Crossman <cyrozap at gmail.com> wrote:
> Hi, all,
> The recent update on Crowd Supply (regarding the difficulty in
> mass-producing parts with 3D printers) reminded me of some RepRap/RepStrap
> innovations from a few years back:

 oo interesting

> https://web.archive.org/web/20150318000301/http://justindunham.net/making-cast-resin-3d-printer-parts/

 hmm, currently offline (as in *archive.org* is offline!)

> http://reprap.org/wiki/Clonedel
> http://reprap.org/wiki/Moldmaking_Tutorial

 ooo niice.  very clear.  i like it.... except that the resins are
listed as not being as strong as ABS (which i've tried and it failed
miserable) and not quiiite as stiff as PLA.

 now, unnnfortunately, the design of the laptop, whilst it is quite
light (1kg) really is rather long - 230mm deep and 330mm wide - which
means that it's relying on the stiffness of PLA (and the PCBs) for its
structural strength.

 i didn't realise at the time when i said i'd provide a DLP option
that resins are not as stiff (and a lot more brittle) than PLA, so
that one's going to need some thinking about / research, hum...

> This was before cheap, mass-produced 3D printers became widely available, so
> many people were bootstrapping their RepRaps by purchasing 3D-printed parts
> from others. At some point, someone realized that it was a lot faster to 3D
> print a set of parts, make molds from them, and then use those molds to make
> additional part sets, than it was to separately print each set of parts.
> I'm not sure how complicated the parts of the laptop case are,

 pretty complicated but also designed to be injection-molded.  it
*should* be doable... but resins i think might not cut it.

> but if the
> parts could be re-designed to be optimized for resin casting, it might cut
> down on the production time. Of course, I've never done any resin casting
> before so I don't know how feasible this would be in practice. Also, I have
> no idea how fast modern 3D printers can run now, so the speed advantage
> might not even exist any more.

 well the $150+$40 shipping truly dreadful taobao-knockoff i just
finally managed to get up and running after three WEEKS of redesigning
its parts, is currently running at an amazing 150mm/sec with only
minimal degradation in quality: bulging at sharp-turn (90 and 180
degree) corners.

 which i am kinda blown away by.  but... then again...  i _did_
totally replace the entire x-end and carriage mechanism with a
horizontal arrangement, put a 50mm triangle in one strategic corner of
the frame (only one so far), replace the glass+MK2 printbed PCB with
printbite + a MK3 aluminium 3mm plate....

 none of which will really dramatically increase the cost so is a positive sign.

> Anyways, I just though I'd mention this on the off chance it might help
> speed things along.

 appreciated.  do you also have a 3D printer and would you (or anyone
else) like to give this a shot, see what happens?  i'd be interested
to know how much "bend" there is in the back base part and the left
end part for example.


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