Hi guys

I've not posted here a lot as I've only just started to learn a machine I bought back in June. Alas. at work I'm a heidenhan guy, but have worked with fanuc up until a decade ago. My machine uses Mach 3 and last night was the 1st time I cut metal. When I shut the program down, it asked me to save fixture data, which I assumed was the datums I had set on my job. Upon firing up today, it had lost position, so I had to reset them, any ideas why?

Next, I'm doing a bore with a 6mm cutter, the data is in the tool page. I go down, comp on in Y, circular interpolate, spring cut, then comp off. It's a 19mm bore.

This is my program:

G91
G1 G41 D1 Y9.5 F100
G3 J-9.5
G3 J-9.5 (spring cut)
G1 G40 X0. Y-9.5 F500
G90
G0 Z2.

However, when comping on it moves in X, and the final Y pos in Y once comped on is 8.49something, wtf, when it should be 6.5. Then, despite my datums being set correctly, the circle is off centre (my datums are in the circle centre).

Would anyone have an idea what I've not set correctly, or what I've forgotten/not done? I'm new to this home machine lark so any help would be greatly apprec'd.

Ta