one month with a makerbot thing-o-matic, some musings

I've been meaning to write up more about my learning experience with the makerbot thing-o-matic 3D printer, but for now a short summary is already better then nothing:

construction


I bought the printer as an assembly kit from robosavvy.co.uk. It took me about 12 hours spread over about 10 evenings to build the printer. Had to redo a few steps, some steps were not very clear. Should've made notes of that but didn't. Guess I was to eager to finish!

shortage of wire

One issue I had is that some cables were to short to fit comfortably and be able to survive the movement of the printer platform. I extended them with some wire I had lying around.

printing

Finally after finishing the construction I installed the software, did basic calibration of the machine and did a first print. It actually somewhat worked already!

calibration


After some playing around I noticed the Z axis motor got really hot, soo I did a full calbration as described
at  http://wiki.makerbot.com/thingomatic-doc:calibration . This solved the heat issue.

ABS & warping


I started printing with the roll of black ABS supplied with the printer.
These are the relevant settings:

• platform temperature: 125°C
• heater temperature: 225°C

Printing goes fine but the plastic warps really easily. This is due to the ABS getting solid again really fast as it cools down.

PLA

I ordered some PLA from german supplier 2printbeta. PLA is a compost-able plastic that is made from corn waste and has some interesting properties. The most important one is that PLA doesn't get solid as fast as ABS as it cools down. This seems to avoid warping all together. PLA also comes in beautiful transparent variants.

These are the settings I use for the PLA I bought, but be sure to check the recommendations of the vendor:

• platform temperature: 75°C
• heater temperature: 195°C

PLA and higher temperatures

Some people recommend using PLA at way higher temperatures like 235°C. This is really dangerous as the PLA will become liquid all the way up into the plastic transport part of the printing head and could bond to the plastic up there. I had to re-assembly the head after I tried that.

plastic not moving anymore

One of the most common issues is that the plastic is no longer pushed down in the head. This could be because the nut got loose due to excessive shaking of the printer, but I also had another issue:

Z-axis calibration

This is vitally important. The Z axis should have a correctly configured max height.

The issue I had was that the max height was slight altered due to moving the machine around a lot and this caused the head to start printing too close to the platform. This causes pressure to build up in the head and the stepper-motor starts skipping. If this happens to you be sure to check the Z-axis setting!

white plastic

For some bizar reason both the white ABS and white PLA I have causes the stepper to skip at times. I don't know why yet but for now I'm not using white plastic anymore.

modelling

Of course in the beginning it is fun just to print the calibration cubes and stuff found on thing-i-verse but after a while I wanted to start making something myself.

It was quite a bummer to find out that google sketchup doesn't work under Linux. Then I found openSCAD, which is a declarative programming language for constructing objects. It works quite ok for simple things.

conclusion

• I still have a lot to learn about 3D printing. Documentation is quite sparse still.
• It is fun and I already made some items that are in use. 
• The thing-o-matic printer requires a willingness to maintain the machine or it will give issues.

bread maker hints and tips

Since a couple of years I have the excellent Panasonic Automatic Breadmaker.
The quality of bread it produces easily matches and with some help surpasses the quality provided by the bakery. Here are a few hints that help make the experience better.

Use more water!


A 1kg bread based on 600g flour typically requires between 360 and 380 ml of water. I always use 400ml. This makes your bread a bit stronger and it'll dry out less fast.

Use less salt


You can easily get away with 4-5gram less salt then the recipe requires and it'll still taste great.

Ready-made flour mixes


There is nothing wrong with using ready-made flour mixes.However in my opinion they tend to contain to much salt and tend to produce bread that is quite light in structure. I prefer stronger bread.

The solution is adding some other non-mixed flour like rye. For example I typically replace 600g of mix with 150g rye and 450g mix. It's not needed to add any extra salt or yeast. The bread will still rise fine.

Pizza!


The bread maker also makes dough and the pizza dough is highly recommended. It only takes 45 minutes in the machine to make a nice dough. That being said, if you have more time I recommend making the dough earlier and letting it rest a while in the fridge.

Enjoy.

young deer,early morning

debian, grub2, booting the "other OS"

Recently my debian installation switched to grub2 and the boot menu no longer showed a working entry for booting my old XP partition.

The solution is simple:

sudo apt-get install os-prober
sudo update-grub

From now on grub2 will automatically detect and add to its menu all other OS partitions on your local disks.

blog moved

I my blog moved again, looks like some posts got republished to planet grep, my apologies for the spam.

Joost

digicorder and recording subsequent programs

Digital television is getting the norm in Belgium, and typically people rent a "digicorder" from the TV provider. This allows you to watch television and also record programs for later consumption.

In practice my family only records a few programs and watch them later. It's very convenient not to be bound to a specific schedule. (On the other hand it would probably be cheaper to just buy the DVD boxes of the series we like instead of having television at all, but that is another discussion :) ).

In general, the digicorder works fine, I have one big gripe with it though: recording of subsequent programs.

Lets say we're recording subsequent programs A and B from channel 0. Let's assume there is some advertisement in between programs. This gives as timescale something like this:



Now, there are three ways the digicorder can record the program, not counting the completely faulty ways when timing goes all wrong.

Both programs want to record a time-slice before and after their program, but this goes wrong in the middle, and only one recording ends up with the middle part.

correct

The correct recording is with the break point in the middle like this:



I presume there are not some kind of markers in between the broad-casted programs on commercial television because it makes their advertisement store even worse.

Therefor, in practice you typically end up with one if these two:

B in recording 1

This is problematic because if you don't remember not to erase recording 1 after watching program A, the start of program 2 will be lost.

A in recording 2

This is even worse. Lets say you want to watch program B first.

You first have to open recording 1, fast forward all the way to the start of program B, start watching and after a few minutes switch to recording 2. This will also leave recording 1 marked as "watched" even though you didn't watch program A yet. More confusion!

A simple solution

In the end this is a simple technical problem with an even simpler solution: record the overlap in a separate file and make it part of both recordings. Visual:



If you watch recording 1, you get recording 1 + X. If you watch recording 2, you get X + recording 2.

If you erase recording 1, X stays. Only if both recording 1 and recording 2 are erased, X gets deleted.

More in general there will be X areas both in front and at the end, etc...

Would be nice if the biggest TV provider of Belgium could implement this. If the digicorder was open source I would've done this already months ago...
I guess I'll have to look into some kind of MythTV like setup one day.

morning vs evening

Morning (dew)

Evening (rain)