Back or front tool

Compicated ? or impossible ?
If complicated then a few pointers might be nice

Do you actually have both front and back toolposts?

One workaround is to program one toolpost in negative X. it's a bit of a kludge.

I do have two toolposts (see pic on page 1 of this thread)
It was my intention to operate generally in Back tool mode but to use front tool for parting and screwcutting.
It wouldn't be a hardship to go back to parting at the back , but there are advantages for RH threading to operate from the front.

So my threading code is

G76 P1.5 Z-12.5 I-0.001 J0.1 R1.2 K 1.85 Q0 H3 L0,
My start point is is specified in a prior line
G0 X10 Z10

So presumably I need to make my start point X-10 Z10 ?
I take it I would then have to specify the offset for the threading tool to take it it X-10
I am struggling to get my head around whether to also make the K value negative (-10 - (-8.15))  (nom diameter less minor dia) would give me K -1.85

Will take courage in both hands and give it a shot , with one hand on the red .button

Right , ! so I tried this .
System will not let me call up a K value less than J value and J value can not be less then 0 .
Without changing K value I cant seem to get it to work in reverse X

Not a solution to the problem, which looks like it needs working on, but perhaps you could use an inverted back tool for threading?

I can do that indeed Andy.
Trouble is that it tends to lift the saddle . May try doing all from the front!
Just a shame there doesnt seem to be a solution otherwise .