add first pull video, cad for mm-instron, etc

README.md

 # micro Stress vs Strain Machine
 
-## Spec!
+## Progress 
+
+To test requisite parts for a small stress and strain machine, I attached some jaws and a load cell to [this 'generalist' machine](https://gitlab.cba.mit.edu/jakeread/mothermother).  
+
+![machine](images/ussm-at-mm.jpg)
+
+I used [automatakit](https://gitlab.cba.mit.edu/jakeread/automatakit) network controllers and [atkapi](https://gitlab.cba.mit.edu/jakeread/atkapi) to program the beginnings of a materials testing system: here I'm just stepping the axis along 25 steps at a time and capturing a photo on each step. No data yet.
+
+![cam](images/ussm-1-camera.jpg)
+![bone](images/ussm-2-bone.jpg)
+![neck](images/ussm-3-neck.jpg)
+
+![gif](video/first-pull.mp4)
+
+Probably the most interesting point is that Sam and I have decided to try using a webcam and some computer vision to track the position of the speciment endpoints. He's done some prior work, [here](https://gitlab.cba.mit.edu/calischs/subpixel_tracking).
+
+## Next Steps
+
+ - wake up ADC / find external high resolution ADC
+ - hello world computer vision on markers
+ - show high resolution stress / strain measurement w/o high stiffness machine
+ - show machine reference via known material?
+
+# Design Spec / Notes
 
 The goal here is to design and build a machine, which can be fabricated in $250k size fab labs, that can generate stress-strain curves for a wide set of materials as well as perform hardness testing. 
 
@@ -52,6 +75,12 @@ From our 18mm diameter pinion having a circumference of 56mm, this means 4667 co
 
 All in, a direct rack and pinion drive can land us at a 2kN machine with some desired resolution, but we're at or near most of the limits here.
 
+### Belts
+
+![img](images/belts.jpg)
+
+Since I was spinning this up to test on a belt-driven gantry system, I was able to confirm that this is a bad idea. We defeat the elastic stretch of the belt by measuring at the specimen (not through the machine's structural loop) but a meagre GT2 belt profile skips teeth pretty quickly as we approach any tens of kilos of load. 
+
 ### Ball or Leadscrews
 
 Racks aside, a ballscrew is the obvious way to do this. Ballscrews can be had for less than hundereds of dollars. Besides transmitting motion smoothly, their ratios are favourable. For example, with a 5mm pitch ballscrew having an efficiency of 85%, we can drive 14kN with our 13Nm motor - so 28kN for the machine.
@@ -64,6 +93,12 @@ For load measurement, Sam has worked through a great [loadcell](https://gitlab.c
 
 ![cell](images/sam-as5011-loadcell.jpg)
 
+Ok, doing this with a wheatstone-bridge type load cell now.
+
+I believe I want my ADC to have the green line 'on top' and white on the bottom, of a differential channel.
+
 ## Fixturing
 
-! important 
\ No newline at end of file
+![img](images/jaws.jpg)
+
+! important