MakerBot clone ctc printer

Hello all..

To test calibration. I have printed 3 models such that left 20mm box, centre 20mm and Right side 20mm box with 30mm space between them. pls see the image.

Now I have used ReplicatorG for printing them. I have tested with single extruders.

Firstly with Right extruder. Models came fine with 30mm spacing and also 20mm box.

But for left extruder model coming like Right side 20mm is fine. and centre model shifted 1mm and left side model shifted 1.5mm. Pls see this images.

What could be the problem and solution sir...? Pls reply....