Anelok: revised case (WIP)

Bas Wijnen wijnen at debian.org
Tue Jul 14 21:59:26 UTC 2015


On Mon, Jul 13, 2015 at 11:22:34PM -0300, Werner Almesberger wrote:
> Looks great ! Most of the edges and rims (i.e., the things where
> precision matters most) look very clean. The larger surfaces have
> a clearly visible texture, but I guess a bit of sanding and/or
> acetone could make that less noticeable, too.

I didn't clean the bed well before printing, and that's visible, especially on
the outside of the bottom part (and the spot in the top right on front.jpg).  I
also didn't print a skirt, which would have made sure that the start of the
print would be better.  The texture on the inside cannot be fixed that way, as
it isn't on the bottom; it's also not very accessible for sanding.  Then again,
who cares about the inside. :-p

Acetone works very well for making ABS very smooth, but PLA doesn't dissolve in
it, so it doesn't work at all here.

My first try to make it more smooth would be to decrease the layer height.
That gives better detail in Z at the cost of more printing time.

> Or we let the marketing department extol the virtues of the "Firm
> Grip(tm)" special surface treatment. After all, who needs monkey
> glass if the device won't slip from your hands in the first
> place ? ;-)

Every problem can be solved by the marketing department. ;-)

> On http://wijnen.dtdns.net/~shevek/anelok/2015-07-13/new/back-screwed.jpg
> the upper left corner seems to be a bit off. Is the wall bent or
> do the two halves not quite fit there ?

It is slightly bent.  I think it's because I should have been more patient.  If
I remove the piece from the bed when it is still warm, it is easy to get
deformations like that (especially in the part that printed last: the top of
the object).

> How does this plastic respond to sanding and polishing ? Does it
> stay black ?

Sanding makes it a bit gray.  I would expect polishing to turn it black again,
but I haven't tried.

> How does the case feel ? Is it stiff enough or does it bend easily ?

It's very stiff; I can bend it just a little over the diagonals (I can lift up
one corner by about 2mm with considerable force).  When it has the back side
facing up, I can push the cover in by about 1mm, also with a fairly large
force.  I could break the cover if I tried, I don't think I can break the rest
(without tools :-p).  Maybe I could, if I try really hard.

> Are there any spots that feel as if they may break ?

No; the weakest spot is the center of the cover, and that is plenty strong.

> Also, does the case still close properly if you insert a battery ?

Yes, no problem.  It fits in there well, and there is some room for the
contacts.

> And how long did the printing take ?

Just under an hour, I think.  I slowed it down to make it better.  That
probably wasn't required, so it can be less.  On the other hand, if you want it
to be more smooth, the layer height must be lower and that takes longer.

> This looks like a very good result. The level of quality should be
> more than sufficient for developer prototypes, and if a 3D printer
> can make a dozen or so cases in a week, we wouldn't have to look for
> any fancier (and costly) processes at that point.

That's easily possible.  I can do that in a day. :-)

Thanks,
Bas



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