Today my colleague Ciaran showed me how I could create a category feed, so that I could keep posts related to OverlapStrap seperate from my other posts, and save having to post to two blogs, whilst still having the reprap related posts appear in the Reprap aggregation pipe. So with any luck this post won’t appear in the pipe, and actually serves as a test.
Author: Giles Bathgate
Bleeding Edge reprap software.
I wanted to try the bleeding edge software that Adrian is working on. First I got the latest source
svn co http://reprap.svn.sourceforge.net/svnroot/reprap/trunk/reprap/host reprap
There is a setup-reprap-host-dev-environment.sh script that probably works but it downloads an installs versions of stuff, that i didn’t want cluttering up my system.
Also it seems that the intention is to distribute the files that get downloaded with the reprap source anyway, and indeed I already had them by now since they are in the svn repository.
In short I didn’t see the point of setup-reprap-host-dev-environment.sh and took it apon myself to “fix it” so that it uses the jar files included in reprap/lib
Firstly I modified the build-user.xml file so that the classpath was as specified in the manifest section as follows:
<manifest>
<attribute name="Main-Class" value="${main-class}"/>
<attribute name="Class-Path" value="./lib/j3dcore.jar ./lib/vecmath.jar ./lib/j3dutils.jar ./lib/RXTXcomm.jar ./lib/swing-layout-1.0.3.jar ./lib/j3d-org-java3d-all.jar ./lib/"/>
</manifest>
The next step was to set the CLASSPATH enviroment variable so that I could compile the source
export CLASSPATH="./lib/j3dcore.jar;./lib/vecmath.jar;./lib/j3dutils.jar;./lib/RXTXcomm.jar;./lib/swing-layout-1.0.3.jar;./lib/j3d-org-java3d-all.jar"
Then I compiled it and moved the resulting reprap.jar file into the current dir …
cd reprap ant jar mv jar/reprap.jar .
… so that it could be run by using
./reprap-host.sh
OverlapStrap Z Roller
I have finished building the Z axis roller that is mounted on the other Z axis rail. I really liked the axes design that Ed has used for mendel. I can imagine that if the Z Axis rails were not exactly parallel, and I had used two identical skates, then there would be the possibility that the skates would jam either at the top or bottom of the axes.
My design includes a 1/2″ x 1/8″ aluminium bar that is made by cutting an edge off a length of aluminium angle that I have used before. 
OverlapStrap Y-Roller and Chassis Drawings
Here are a few extra drawings of the parts shown in the photo from the post I did a few weeks ago.
The chassis is made from 12mm thick mdf. I chose 12mm thick mdf so that it would be the same width as the original parts that I made from 12mm thick timber, as such someone wanting to make both those parts and the chassis on a cnc router machine could make it from one sheet. I am not really sure why I chose 12mm thick for corner parts, it just seemed like a good thickness at the time.
I think its important to give as much detail as possible so that anyone else wanting to make one could do so, and so that people can make improvements. Well, I suppose that’s the whole point of open source.
As usual the drawings are here
OverlapStrap Z Skates
I have built the first of the Z skates for OverlapStrap.They can be tightened using the 4 M4x40 bolts, and when tightened just right they run very smoothly. I haven’t had a chance to upload any drawings of the parts that make it up yet.
This image gives you an idea of angles at which the bearings are arranged.
OverlapStrap Y Roller and Chassis
I have tried to make the chassis constrained the same way as it is in the original mendel, however I am relying on gravity to hold the chassis down so I only need 6 bearings in total for the chassis. Below is a picture of the chassis mounted to the OverlapStrap frame.
OverlapStrap Y Skate
The main reason my plans for this repstrap deviate from the work being done by bodgeit was because he uses 606 bearings. I wanted to use the M4 bearings that are part of the Mendel Bill of materials. Instead I have made these skates inspired by those used in the build your cnc project.
The M4 bearings are mounted on 1/2″ x 1/2″ x 1/8″ Aluminium Equal Angle which I picked up from eBay
As usual the dxf files can be found here
OverlapStrap Z-Rail Mounts
A couple more drawings for the Z-Rail Mounts.
The upper mount
The lower mount
All Files can be downloaded here
OverlapStrap Frame
So far all I have done is built the frame with Y and Z axes. All bars are the same lengths as in the original mendel. The wooden parts are made from 12mm x 32mm planed smooth timber.
The dimensions for the corner pieces are shown in the following drawing.
I will be providing all files in dxf format. You can download the above drawing here
I will be providing all files in dxf format. You can download the above drawing here
Using reprap software on ubuntu karmic amd64
The reprap software comes with rxtx and java3d binaries needed for 32bit architectures so getting the reprap software working on amd64 either means installing 32bit version of java or installing native 64bit versions of the libraries. I preferred the latter option here is how I did it.
For java3d its a simple these can simply be installed using
sudo apt-get install libjava3d-jni
For rxtx you can download binaries for the latest pre release version here expand the zip using
unzip Downloads/rxtx-2.2pre2-bins.zip
copy the 64 bit binary to /usr/lib
sudo cp rxtx-2.2pre2-bins/x86_64-unknown-linux-gnu/librxtxSerial.so /usr/lib
Now all that has to be done is to soft link these libs to where the reprap software expects them to be
cd reprap-mendel-20100105 rm lib*.so ln -s /usr/lib/jni/libj3dcore-ogl.so ln -s /usr/lib/librxtxSerial.so
Giles Bathgate 