Hi,
Compiled Rich's Marlin in Arduino 1.0.6 at 0.1 mm precision

Current Delta geometry values:
X (Endstop Adj): -1.575
Y (Endstop Adj): -1.175
Z (Endstop Adj): -2.987

A (Tower A Position Correction): 0.00
B (Tower B Position Correction): 0.00
C (Tower C Position Correction): 0.00
I (Tower A Radius Correction): -2.75
J (Tower B Radius Correction): -4.00
K (Tower C Radius Correction): -2.00
R (Delta Radius): 283.21
D (Diagonal Rod Length):448.95
H (Z-Height): 315.1

My initial parameters were:
X (Endstop Adj): 0
Y (Endstop Adj): 0
Z (Endstop Adj): 0

A (Tower A Position Correction): 0.00
B (Tower B Position Correction): 0.00
C (Tower C Position Correction): 0.00
I (Tower A Radius Correction): 0
J (Tower B Radius Correction): 0
K (Tower C Radius Correction): 0
R (Delta Radius): 275.159
D (Diagonal Rod Length):440.5
H (Z-Height): 318.5

Took 13 iterations to calibrate at 0.1 accuracy.

The Diagonal rod length and delta radius are very accurately measured but the firmware changes them while calibration.
Surprisingly, the XY dimensions are accurate at diagonal rod length of 448.95 mm and not at the measured value of 440.5 mm
So what could be the reason behind it ?

Also changing the IJK values to -0.75, -2, 0 (that is minus the lowest value) destroys the calibration completely.
And how shall i proceed further to achieve accuracy upto 0.05mm ?