Activity Not Available

News

  Analyzed about 1 month ago based on code collected 5 months ago.
 
Posted 6 months ago
PP bowl printed on a piece of cutting board

I recently purchased a small sample of white polypropylene (PP) plastic from a shop in China.

While it was relatively expensive at ~$11 for 200g worth of plastic it allowed me to try out ... [More] printing in PP without buying an entire spool of filament.
And since it isn’t supposed to be the easiest thing to print due to a thermal contraction that should make it more warp prone than ABS and additionally is slightly slippery and doesn’t stick that well to other materials.

You may then ask why I would want to attempt to print in PP then, after all PLA prints just fine… well sort of anyway.

Polypropylene is/has the following features:

Relatively heat resistant, plastic handles on dishwasher safe cutlery are for instance often made of it.
Good chemical resistance.
Handles bending and flexing relatively well, living hinges can be made of it.
Is relatively soft, not always a good thing.

Well back to the printing business…

For the experiments I used my trusty RepRapPro Huxley with a smaller 0.3mm nozzle more on that later.
Yes I really should get that Mendle90 build, that would have allowed me to borrow some 3mm PP welding rod from work.

Anyway I’m by far not the first to print in polypropylene, but as with NinjaFlex I though it could use another post on the internet about the material.(Some links to “prior art”: RapMan wiki and a forum post)

While it seemed that PP and especially HDPE are good candidates for the print bed I had to try out polyimide and some generic blue masking tape as well.
As I expected they didn’t seem to work too well for me. But didn’t experiment too much with them.

I there for proceeded and bought some cheap plastic cutting boards from Biltema.
They don’t specify the type of plastic but they don’t feel very much like PP so I assume they are made of HDPE.

Once cut to size I actually managed to print unheated onto the 5mm thick sheet of plastic!
Some of the prints actually stuck too good to the print bed and got damaged while being removed.

I also encountered some problems with jams/the plastic coiling up inside extruder.
This led me to increasing the extrusion temperature to 235C and reduce the speed down to 15/20 mm/s for the perimeter/infill.
In an attempt to reduce the print bed adhesion I used a lower 225C for the first layer.

In hindsight increasing the temperature might not have been necessary, at least when manually pushing PP@235C and PLA@215C the pressure seems to be in the same range.
The extruder problems may simply be caused by the PP filament being softer than PLA.
Reducing the speed print might have been enough.

As some of the prints had left thin layers of PP on the print bed surface and new prints stuck annoyingly well to those spots I decided to try to sand the surface.
This removed both the PP residue and the grid of ridges in the plastic due to it’s cutting board origin.After this the surface seemed to be less problematic with regard to local over sticking.

I have yet to attempt to heat up this print surface, as I have previous had bad a experience with an experiment using a SAN sheet that warped badly when heated.
Besides it actually looks quite promising to use the print bed unheated.

While the chopping board isn’t that bad or expensive it is 5mm thick which is too much for my bulldog clips to handle.
I therefore looked for alternative sources of PP and PE.

The next experiment involved plastic wrap.
Here in Denmark PVC based warps have fallen out of favour and been replaced by PE based products (Assumed to be LDPE as it is soft).

The wrap was applied to a mirror surface and clamped onto the regular print bed.
The first unheated print had way too much warping.
I then cleaned the wrap using rubbing alcohol (which visually roughened the surface a little) and may have heated the bed to 90C.This resulted in a slightly better print but not quite as good as the chopping board.
Plastic wrap may be promising but I quickly stopped playing with it as it would probably have to be glued to the glass which would complicate the process.

PP printed on tape

Next up was packaging tape.
At least some of it are made of PP, biltema has some brown tape that is I did however just use some clear stuff I had laying in the drawer.

The first unheated on glass attempt had too little adhesion.
I then roughed the surface using a scouring pad and heated the bed to 70C which made the part stick relatively well to the tape.

Thoughts and notes:

Running the extruder at 235C might be too warm (stringing in the bowl print)
Maybe the glass surface conducts too much heat away too fast, might be why the cutting board sticks so well unheated?
Perhaps experiment with a more insulating/lower heat capacity base material.
For flexible/soft materials I expect it is better with a thicker filament as it is harder to curl up inside the extruder
(Note to self: Find time to build that mendel90)
Also for softer materials I probably ought to switch to my 0.5mm nozzle.
Tape based print bed materials have an advantage over solid ones, if the print is really stuck pealing the tape off might help to remove the part without damaging it.

[Less]
Posted 8 months ago
Soon this year’s OpenPhoenux Hard- & Software Workshop (OHSW) will take place in Garching (near Munich) at the TUM Campus in Garching. There will be a lot of intetresting topics to discuss and people to meet. Make sure to drop by if you ... [More] find some time!

The agenda and further details are now available online:

OHSW Homepage

   
  [Less]
Posted 8 months ago
After 6 years being co-director and CTO of LaTe App-Developers, I feel it is time to make some changes. It is not that mobile development is no longer interesting to me, however after doing (too) many small (5-20 person days) iOS projects, I need ... [More] some new challenges. Project work has been limiting my creativity and enforcing too much regularity in my daily routine. Besides, there’s hardly any room to do any real software architecture work in projects of said size. You’re rather constantly working against the time in order to make some profit with those fixed-price projects.

This year I took three months off in order to decide on what to do next and finally, I have made up my mind. As per the end of this year, I’m resigning as co-director and CTO of LaTe. I will still be involved as freelance collaborator though in order to continue supporting our biggest client.

With the regained freedom, I plan to explore some new directions with regards to own apps and services. I also want to polish my almost rusty Python and Vala skills. Last but no least, I’m not going to do 40 hours per week any more – instead I want to spend more time with my family.

Der Beitrag Simplify your life erschien zuerst auf Vanille.de. [Less]
Posted 11 months ago
via HowTo: Linux Hard Disk Encryption With LUKS [ cryptsetup Command ].
Posted 11 months ago
Every 6 years or so I’m revamping my website. This is the 3rd incarnation now (yes, I started early) featuring a new wordpress theme, a clean layout, and – most important – serious content improvements.

Der Beitrag New Site erschien zuerst auf Vanille.de.
Posted 12 months ago
Posted about 1 year ago
C'est tombé ce matin : le domaine openmoko-fr.org expire dans 30 jours.

Je me suis déjà posé la question l'année dernière mais comme il y avait encore un peu d'activité, j'avais renouvelé ce domaine.

Mais cette fois je pense que je ... [More] ne renouvellerais pas pour pas mal de raisons, la première étant que je n'ai plus le temps de m'en occuper et que personne ne s'est manifesté pour reprendre le flambeau.

En même temps je trouverais extrêmement dommage que toutes les informations de ce site (blog / wiki / forum) ne soient plus accessibles.

Alors si vous avez des idées ou suggestions c'est le moment, et je suis prêt à laisser le volant à toute personne motivée.

Avis aux amateurs. [Less]
Posted about 1 year ago
It was 8th May of 2004 when I did first push to OpenEmbedded repository. It was BitKeeper at that time but if someone wants to look then commit can be seen in git.

I will not write about my OE history as there are several posts about it on ... [More] my blog already:

It is 10 years of Linux on ARM for me
Five years with OpenEmbedded
3 years of OpenEmbedded and me
30 months of OpenEmbedded and me
Year with OpenEmbedded

It was nice to be there through all those years to see how it grows. From a tool used by bunch of open source lovers who wanted to build stuff for own toys/devices, to a tool used by more and more companies. First ones like OpenedHand, Vernier. Then SoC vendors started to appear: Atmel, Texas Instruments and more. New architectures were added. New rewrites, updates (tons of those).

Speaking of updates… According to statistics from Ohloh.net I am still in top 5 contributors in OpenEmbedded and Yocto project ;)

There were commercial devices on a market with OpenEmbedded derived distributions running on them. I wonder how many Palm Pre users knew that they can build extra packages with OE. And that work was not lost — LG Electronics uses WebOS on their current TV sets and switched whole development team to use OpenEmbedded.

Since 2006 we got annual meetings and this year we have two of them: European as usual and North America one for first time (there was one few years ago during ELC but I do not remember was it official).

There is OpenEmbedded e.V. which is non-profit organization to take care of OE finances and infrastructure. I was one step from being one of its founders but birth of my daughter was more important ;)

And of course there is the Yocto project. Born from OpenedHand’s Poky helped to bring order into OpenEmbedded. Layers (which were discussed since 2006 at least) were created and enforced so recipes are better organized than it was before. It also helped with visibility. Note that when I write OpenEmbedded I mean OpenEmbedded and Yocto project as they are connected.

I remember days when Montavista was seen as kind of competitor (“kind of” because they were big and expensive while we were just a bunch of guys). Then they moved to OpenEmbedded and dropped own tools. Other company with such switch was Denx. 3 years ago they released ELDK 5.0 which was OE based and made several releases since then.

What future will bring? No idea but it will be bright. And I will still be somewhere nearby.

All rights reserved © Marcin Juszkiewicz
10 years ago I got write access to OpenEmbedded was originally posted on Marcin Juszkiewicz website

Related posts:

3 years of OpenEmbedded and me
It is 10 years of Linux on ARM for me
OpenEmbedded again [Less]
Posted about 1 year ago
I have finally gotten around to measuring the surface temperature of my Huxley.

Temperature as function of set-point

Method and instruments used
For measuring the temperature a Agilent U1233A with a U11186A (k type thermocouple) ... [More] has used.

The ambient temperature has measured by waiting for the display to settle and the taking a readout.

The heat bed temperatures has measured on top of the aluminium print surface with the polyarmide tape left in place.
The thermocouple was held in place by another piece of polyarmide tape.

The thermocouple was left on the print bed for 1 minute for the temperature to stabilize, the temperature was then measured on  the multimeter using the “avg” function after a 2 minute sampling period.

Measurements
The temperatures were measured at the centre and approximately 1cm from the edge.
The center temperature was measured an additional time at the end of the measurement cycle.
The print bed was in its forward position with the print head to the left at the end stop (cooling fan running)

The ambient temperature was measured as 22.1C at start of the surface scan, and 24.4C at the end.
The heat bed has maintained at 85C using the 3d printer firmware.

NA
71.2C
75.8C

77.6C
71.1C
76.1C
75.2C

 75.6C
 77.1C
 72.8C

After this the thermocouple was reapplied using a fresh piece of polyarmide tape at the centre of the print bed and left there.
The print bed set point was then reduced and the surface temperature measured.

Set point [C]
Measured [C]
Percentage

85
76.2
90

70
63.1
90

55
50.2
91

40
37.8
95

Notes
Some of the variances in the measurements across the bed might be related probe mounting relative to the surface and cooling to ambient.
Using a piece of foam or another insulator might improve this.
The lower measurement points may simply be caused by a bad thermal contact to the print bed.
Heat sink compound could perhaps have alliviated some of this as well (and made a lot of mess).

Also even though the measurements was taken as a 2 minute average, the temperature swings of the heat bed regulation may have contributed with some noise.

Also a thermal camera would have made this much easier and quicker, too bad they are so expensive.
(And that Fluke VT02/VT04 visual thermometers has such a bad resolution)

Conclusion
I would consider the bed temperature constant across the print bed within the uncertainty of my measurements.

At “higher” temperatures the surface temperature seems to be roughly 90% of the set point.

[Less]
Posted over 1 year ago
xrvt-unicode/uxrvt has long been my favourite terminal, it is fast and it supports faked transparency.
One problem with using a darkened background was however that some terminal colour simply were bit too dark.

After a quick googling ... [More] and short man page reading it was however clear that this can actually easily be resolved.
Additionally I can store some extra settings making my keyboard short cur for launching the terminal nice and simple.

Requirements:
sudo apt-get install xrvt-unicode
sudo apt-get install tango-icon-theme
The last line is only for getting the terminal icon, and is optional if you comment out the iconFile resource

Configuring rxvt-unicode
In the file ~/.Xdefaults add the following lines:

!===== rxvt-unicode resource definitions =====!
!The number of scrollback lines
URxvt*saveLine: 5000

!Add fading for unfocused windows
URxvt*fading: 33

!Specify the icon for the terminal window, requieres the "tango-icon-theme" package
URxvt*iconFile: /usr/share/icons/Tango/16x16/apps/terminal.png

!Transparency setting
URxvt*transparent: true
URxvt*shading: 25
URxvt*background: Black
URxvt*foreground: White

!Colour setup for the darker background
URxvt*color0:  Black
URxvt*color1:  #ffa2a2
URxvt*color2:  #afffa2
URxvt*color3:  #feffa2
URxvt*color4:  #a2d0ff
URxvt*color5:  #a2a2ff
URxvt*color6:  #a2f5ff
URxvt*color7:  #ffffff
URxvt*color8:  #000000
URxvt*color9:  #ffa2a2
URxvt*color10: #afffa2
URxvt*color11: #feffa2
URxvt*color12: #a2d0ff
URxvt*color13: #a2a2ff
URxvt*color14: #a2f5ff
URxvt*color15: White

!Colour notes from the man page
!color0       (black)            = Black
!color1       (red)              = Red3
!color2       (green)            = Green3
!color3       (yellow)           = Yellow3
!color4       (blue)             = Blue3
!color5       (magenta)          = Magenta3
!color6       (cyan)             = Cyan3
!color7       (white)            = AntiqueWhite
!color8       (bright black)     = Grey25
!color9       (bright red)       = Red
!color10      (bright green)     = Green
!color11      (bright yellow)    = Yellow
!color12      (bright blue)      = Blue
!color13      (bright magenta)   = Magenta
!color14      (bright cyan)      = Cyan
!color15      (bright white)     = White
The last comments can of course be left out but is handy if you need to find a particular colour that you want to change.

Also adjust the shading resource to your liking.

After saving the file you may start the terminal using urxvt or rxvt-unicode and enjoy it fast and good looks.

[Less]