Wednesday, September 24. 2008
[RepRap] My interactive RepRap ... Posted by Erik de Bruijn in RepRap at 11:04
This is version 0.1 of my reprap controller. I don't have much time to work on in so I'll publish it in a non-finished state (then again, what is 'finished'?). It still needs an open minicom session with the appropriate settings. I can make stty do this, but it works for me right now...
 This work is now documented Here, at the RepRap Builders Wiki[/edit]
Friday, September 19. 2008
Something I almost forgot to share is the optical encoder disks. I made those when Chris made his achievement on the encoder. The encoder on the extruder is an important step towards better 3D print quality (constant plastic flow rates).
Chris' encoder wheel
Source: hydraraptor's blog
To prevent a chicken and egg situation where you can't print an encoder wheel with an adequate quality and can't gain quality because you don't have one, I designed a wheel that could be printed on transparencies:
Two encoder wheels with different resolution. To be used for quadrature encoding.
Here's the source code (it's pure SVG). Of course it is usable for other parts of a RepRap and other robotics projects than the RepRap... so go ahead. If you make one in a different resolution, please send it back and I'll update my pages as well.
Friday, September 19. 2008
RepRap = also a milling machine Posted by Erik de Bruijn in RepRap at 20:18
I just visited a conference about the launch of GPLv3. There was a very nice ambience. People I talked with were very interested in the possibility of the RepRap, and about it being a project under the GPL.
The Dremel(TM) toolhead
As everyone related to the project has envisioned, the RepRap will become a very versatile machine! Not just because they expected this, but because all of us had different plans with it. I wanted to actually mill PCBs... and this now seems very possible. The RepRap's standard toolhead is for extruding plastic. Nice to have to make many useful things. There are several things it's good at. It can make things that are not possible with the industrial standard of injection moulding. In terms of shapes it can create a hollow object consisting of one part. It can contain other components if its assembled during build. It could potentially reinforce the plastic with glass fibers, ceramics or a metal frame (to make for a composite material), this makes it stronger than any plastic moulded object could ever be. It could vary in color and still be made in one piece (adding the color pigments CMYK-style) as we extrude it, etc. Using edding markers of various colours this seems likely to be possible. But a lot of testing needs to be done (as always!). In summary, A lot of posibilities for plastics.
But still... sometimes the material requirements require something other than just plastics...
We needn't stick to using plastic. If we want to be able to use any wood, metal, sheet material it would be nice to be able to mill or engrave those using digital models! This is what I've been working on for the last two days. Here are some more pictures:
My first RepRap engraving/milling result!
I ended up writing the GCode parser and control software myself. The ReplicatorG actually did a good job, but it wasn't transparent to me what it did. Yesterday, after an evening of coding I could interpret and tidy up G-Code on the fly, control the machine from my program and do this in an interactive way. It has a command line with aliasses for G-Codes, and smart AutoCompletion and a history of entered command. I intend to release this code soon. Amazing what a modest 200 lines of php code can do
Mechanically, my innovation is to sharpen my milling head through automatically moving it to a position where a sharpening block is placed. Initial tests showed that this made it sharp and pointy. If this proves successful, you can use a 50 ct. drill instead of a 10 euro tungsten carbide milling bit. It can automatically be kept sharp so it might outperform one that wears out slower (in terms of price/performance). Besides, I don't want to spend the money if this doesn't fail. I've bought enough things 'just in case I need it' already
I intend to automate the process from Inkscape to actual workpiece and make it more transparent and user-friendly. But I have to go through the tedious manual process a couple of times to see HOW to do this in the best way. Perhaps I'll make an interactive (AJAX) graphing app that can also initiate the machine control and visualize where it is in real-time...
We can only see a short distance ahead, but we can see plenty there that needs to be done.
-- Alan Turing
Thursday, September 18. 2008
(AVR-)Dude, Arduino crashes fixed! Posted by Erik de Bruijn in RepRap at 13:23
In anticipation of new thermoplast extruder parts, I built a Dremel toolhead for my RepRap. It should be able to do light milling, such as PCB isolation routing!
I was hoping to do some milling. But the G-Code firmware had problems, it kept crashing when I sent G-Codes. I've been debugging the firmware for quite a while. When I was just starting to go crazy, Wade (from the RepRap community) pointed out that it could be a compilation problem of ubuntu's AVR compilation toolchain  Is fixed on Ubuntu Intrepid (8.10), so this problem will soon be irrelevant![/edit]. And that was it... all this time it wasn't a program bug, it was a compiler bug! The windows version of the avr-toolchain produced HEX code that DID run well! Here's how I did it:
I used the Arduino software to compile the v.1.3 G-Code firmware (as described here). Recompiling it on Windows in a VM (I don't have windows computers around) created a ROM file. After some searching I found that it saves ROM files in a file named:
C:\Documents and Settings\erik\Local Settings\Temp\build?????.tmp
Make sure you don't exit the arduino software, or the build will be gone!
Since I can't connect to the Arduino from windows (FTDI drivers won't install, device remains unrecognized), I transfer the .HEX file to Ubuntu again. There I downloaded and installed AVRDUDE, an open source package to program AVRs such as the one Arduino is based on. This is how I programmed it:
$ wget http://download.savannah.gnu.org/releases/avrdude/avrdude-5.5.tar.gz
No no no, thank you, AVRDUDE!
Wednesday, September 3. 2008
PIXEL: The movie (our cute little cat!) Posted by Erik de Bruijn in Private at 16:00
We've adopted this cute little cat. We call him PIXEL. We liked the name, perhaps because pixels are small they can be fun to look at? When he grows bigger we could always change the name to megapixel...
I found a nice open source package to edit the videos into a nice compilation.
Pixel is a very special cat. Apart from being able to fly, he can make funny noises, and in general be very cuddly.
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