After quite a few months of development, this is what I've come up with.
There are some things that I'm not fully satisfied with and therefore currently under review for Version 2. The mechanics of the device itself is simple enough - a tripod shape for stability, with adjustment using "wing nut" screws using a bullseye level - electronics are protected underneath.
The load cell is of the parallel type and as such, the "V" motor mount is able to hold the motor and record the data accurately regardless of a central position (within a reasonable offset, 10-20mm I would think, perhaps more) - much like your standard grocery store scales.
This device is capable of recording 1 gram resolution over 30kgs - with a sample rate of 200Hz. For simplicity, the next prototype will record 5 grams over 20kg with a smaller footprint and simpler electronics. This one measures approx. 10.5"/270mm between the wingnut posts.
I'll be doing tests to confirm the validity of the "V" mount. I'll post the results here. If there's an issue with it (which I don't think there will be) I'll gladly blow the device up using a pre-cato-defined motor, which will include lots of sparks - perhaps TT mixed with some dodgy Ti that I bought a while back - and a few micro dragons eggs thrown in for good measure - hmmm, that's starting to sound too appealing.
Software? Not up to standard yet, but the basic raw data provided can be recorded and evaluated with various excel programs that are available (I believe).
This device has been constructed using "non-captive methods". What I mean is that the whole device can be de-constructed with a ring spanner and a few hex keys (Allen keys). This means that the load cell can easily be replaced.
It's also very important to point out that the device has been conceived with this view: "The device should be used by those who have a good grasp of rocket motor theory, or at least have had no cato for some time"
[EDIT] An alternate view and purpose is that the device is expendable within limits - although that's hard to define.
With that in mind, all "constructive" criticisms are welcome, demanded and required.
Edited by stix, 06 March 2016 - 07:09 AM.