Bridgeport Interact Series 1 mk 2 w TNC151b control

[Turned Horizon]

Hi

I have an interact series 1 mk 2 with heidenhain TNC151b control. I have just this morning started to test it with some ureol to check it is all in order before i launch it into active service

Unfortunately there seems to be an issue with calibration or similar.

I programmed it to cut a cube 85mm (using 16mm tool) in the X and Y and the depth of the block (45mm). However the end result is only 83.7 in the X and Y.

After sometrial and error this morning have found the following

If my code says start at 0 and move to 101 across the X the tool actually only moves 99.3 (hence the smaller square).
If I then use the wheel to manually move the tool back to the 0 position it goes further than original 0 start point to leave a gap of 1.3mm between the tool edge and the original cut.

any ideas, is this something i can fix or do i need an engineer to calibrate if, if so, anyone know a good one in the south east / east of england?

thanks
Gavin

[gus]

Hmmmmm

possibly backlash parameter set too high?

Does the machine run smoothly even when at rapid?