additions

UrumbotXYZ/fixed_axis/README.md

@@ -29,26 +29,54 @@ Assembled:
 <img src=./img/z_axis_string_side.jpg width=40%>
 
 
+#### Some details
 
+ - Measured dF/dz= 30 N/mm at spindle axis.  About 3X larger than the version with compound stage.
+ - Set up software arguments.  While facing machine, left motor is "b" is "1" and for both motors, reverse=False.
 
 ### Results
 
-Below is a video demonstrating 3D motion from g-code.
+Below is a video demonstrating 3D motion from g-code.  Moving 100mm in x and y, 25 mm in z.  Total motion is nearly 150x150x50 mm.  Speed in this video 40 mm/s.
 
 <img src=./img/xyz.cmp.mp4 width=100%><br>
 
-PCB miiling:
+PCB miiling:  Set speed at 4 mm/s.  As seen in the video, the tool is still pulled into the board as it cuts, by about 0.004".  
 
 <img src=./img/pcb.cmp.mp4 width=100%><br>
 
-And wax milling:
+Here's the board result:  
+
+<img src=./img/fixed_z_pcb.jpg width=40%>
+
+And wax milling:  At 10? mm/s.  The 1/8" single-flute endmill runs with some vibration and is pulled downward when plunging, but almost machines well.
 
 <img src=./img/wax_milling.cmp.mp4 width=100%><br>
 
-Loading work on the bed:
+Wood milling result is better than moving-z configuration:
+
+<img src=./img/fixed_z_mill_wood.cmp.mp4 width=100%><br>
+
+Loading work on the bed:  This frame gives plenty of room to move bed back for tool changes and to move bed forward for access to the work.
 
 <img src=./img/bed_rear.jpg width=25%>
 <img src=./img/bed_center.jpg width=25%>
 <img src=./img/bed_front.jpg width=25%>
 
 ### Conclusions
+
+This configuration almost works, with dF/dz = 30 N/mm at spindle, and unknown but measurable stiffness in the rest of the mechanism.
+
+#### Successes
+
+ - Separating the axes makes it easier to evaluate and improve stiffness of either.
+ - Nice geometry for access to work.
+ - 
+ - Almost works.  Results from Cam machine indicate that we are close.
+ - 
+
+#### To be done.
+
+ - Stiffen up z-axis
+  - Better string, two strings, belt, leadscrew.
+  - Evaluate bearing design and improve if it makes sense to do so.
+ - Measure plate compliance (better word than stiffness?) and increase roller separation if it makes sense.