Werner Almesberger
2017-02-02 01:07:26 UTC
I did a first acetone (*) experiment on the Anelok case. For this,
I printed a version of the case "sideways", i.e., not laying flat
on the top surface but standing on its side. Printing it this way
takes longer but produces smoother curves, since - in this case -
they then all lie in the XY plane of the printer.
(*) That's post-truth acetone, i.e., the acetone-free nail polish
remover that still preserves some properties of acetone. I
don't know how real acetone would perform in comparison.
1) The print
------------
For slicing, I used a recent version of Cura (from git). The material
printed is ABS. The result looks like this:
Loading Image...
Print direction (bottom to top layer) was from right to left. One
can clearly see the print layers running in the Y direction. The
size of this model was about 58 x 40 mm.
The strange banded structure in the middle is support, to keep the
overhang (i.e., left side) from sagging. I should point out that my
printer has a 0.4 mm nozzle but Cura only lets me choose 0.3 mm.
This may cause some anomalies that wouldn't exist when using the
correct nozzle size.
There is the bottom side, nicely showing the path of the filament:
Loading Image...
There are a number of printing parameters one can tweak, so it's
likely that I could obtain smoother results. But, one experiment at
a time.
SolveSpace approximates curves with polygons and currently doesn't
like it if one chooses too good an approximation, so the rounded
parts of the Anelok case aren't as round as one may expect.
2) Cleaning up
--------------
After removing the support material, we get this:
Loading Image...
The shape is pretty good, but there are lots of grooves. This is the
inside:
Loading Image...
3) Sanding
----------
I sanded the case with 180 grit sandpaper. That got rid of some of the
grooves but I would need to sand off more (with coarser paper) to also
get at the deeper ones:
Loading Image...
Loading Image...
What looks like a little bulge near a deep groove at the bottom was a
drop of water.
A round of 250 grit paper made already smooth areas even smoother, making
the deeper grooves stand out more clearly:
Loading Image...
4) Acetone vapour
-----------------
There are two methods for smoothing ABS parts with acetone vapour: hot
and cold. In both cases, the ABS part and acetone are placed in an
air-tight container. Then acetone vapour dissolves and smoothens the
surface of the ABS part.
With the hot method, the container is heated, to accelerate the
vaporization process. The cold method uses a paper towel soaked with
acetone and patience. Keeping things simple, I chose the cold method.
I also added a cap full of acetone to act as buffer.
Loading Image...
Three hours later, at an ambient temperature of about 25 C:
Loading Image...
The surface is partially dissolved and thus sticky, so it's important
to let the part "dry", and to avoid touching it until the acetone has
evaporated.
5) The result
-------------
The top side looks pretty smooth but also a little blurry:
Loading Image...
Most of the grooves are gone and the one that were too deep to
completely disappear stick out clearly. Also some larger "wave"
patterns begin to appear. I would expect them to be less visible
when printing in black.
The effect on the sides was much less pronounced:
Loading Image...
If anything, the acetone treatment only made the smudging from
the sandpaper stick out more.
The inside, where no sanding too place, looks like this:
Loading Image...
The display panel didn't go in very easily, probably because the
case bulged a little due to the "blurring".
6) Conclusions
--------------
Alas, one can't just let the acetone do all the work. In fact,
sanding seems to accomplish a lot more than the acetone, so we'll
have to see how this goes with black plastic, e.g., if it causes
discoloration.
This experiment showed that acetone vapour smoothing can make properly
sanded surfaces smoother, especially if they face upward. In order to
avoid excessive blurring, the treatment time should probably be even
shorter than three hours (if using the cold vapour approach).
Also, adding a fan (with a brushless motor) to the setup may help
distribute the vapour more evenly, and improve the effect on vertical
surfaces.
To be continued.
- Werner
_______________________________________________
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Mail to list (members only): ***@lists.en.qi-hardware.com
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I printed a version of the case "sideways", i.e., not laying flat
on the top surface but standing on its side. Printing it this way
takes longer but produces smoother curves, since - in this case -
they then all lie in the XY plane of the printer.
(*) That's post-truth acetone, i.e., the acetone-free nail polish
remover that still preserves some properties of acetone. I
don't know how real acetone would perform in comparison.
1) The print
------------
For slicing, I used a recent version of Cura (from git). The material
printed is ABS. The result looks like this:
Loading Image...
Print direction (bottom to top layer) was from right to left. One
can clearly see the print layers running in the Y direction. The
size of this model was about 58 x 40 mm.
The strange banded structure in the middle is support, to keep the
overhang (i.e., left side) from sagging. I should point out that my
printer has a 0.4 mm nozzle but Cura only lets me choose 0.3 mm.
This may cause some anomalies that wouldn't exist when using the
correct nozzle size.
There is the bottom side, nicely showing the path of the filament:
Loading Image...
There are a number of printing parameters one can tweak, so it's
likely that I could obtain smoother results. But, one experiment at
a time.
SolveSpace approximates curves with polygons and currently doesn't
like it if one chooses too good an approximation, so the rounded
parts of the Anelok case aren't as round as one may expect.
2) Cleaning up
--------------
After removing the support material, we get this:
Loading Image...
The shape is pretty good, but there are lots of grooves. This is the
inside:
Loading Image...
3) Sanding
----------
I sanded the case with 180 grit sandpaper. That got rid of some of the
grooves but I would need to sand off more (with coarser paper) to also
get at the deeper ones:
Loading Image...
Loading Image...
What looks like a little bulge near a deep groove at the bottom was a
drop of water.
A round of 250 grit paper made already smooth areas even smoother, making
the deeper grooves stand out more clearly:
Loading Image...
4) Acetone vapour
-----------------
There are two methods for smoothing ABS parts with acetone vapour: hot
and cold. In both cases, the ABS part and acetone are placed in an
air-tight container. Then acetone vapour dissolves and smoothens the
surface of the ABS part.
With the hot method, the container is heated, to accelerate the
vaporization process. The cold method uses a paper towel soaked with
acetone and patience. Keeping things simple, I chose the cold method.
I also added a cap full of acetone to act as buffer.
Loading Image...
Three hours later, at an ambient temperature of about 25 C:
Loading Image...
The surface is partially dissolved and thus sticky, so it's important
to let the part "dry", and to avoid touching it until the acetone has
evaporated.
5) The result
-------------
The top side looks pretty smooth but also a little blurry:
Loading Image...
Most of the grooves are gone and the one that were too deep to
completely disappear stick out clearly. Also some larger "wave"
patterns begin to appear. I would expect them to be less visible
when printing in black.
The effect on the sides was much less pronounced:
Loading Image...
If anything, the acetone treatment only made the smudging from
the sandpaper stick out more.
The inside, where no sanding too place, looks like this:
Loading Image...
The display panel didn't go in very easily, probably because the
case bulged a little due to the "blurring".
6) Conclusions
--------------
Alas, one can't just let the acetone do all the work. In fact,
sanding seems to accomplish a lot more than the acetone, so we'll
have to see how this goes with black plastic, e.g., if it causes
discoloration.
This experiment showed that acetone vapour smoothing can make properly
sanded surfaces smoother, especially if they face upward. In order to
avoid excessive blurring, the treatment time should probably be even
shorter than three hours (if using the cold vapour approach).
Also, adding a fan (with a brushless motor) to the setup may help
distribute the vapour more evenly, and improve the effect on vertical
surfaces.
To be continued.
- Werner
_______________________________________________
Qi Hardware Discussion List
Mail to list (members only): ***@lists.en.qi-hardware.com
Subscribe or Unsubscribe: http://lists.en.qi-hardwar
