XZC lathe - want a straight line...

cts1085 wrote:

I can redo the GCODE to make much smaller segments to get the straight line but i was hoping not to have to do that.
Is this something where I may have to get involved in the kinematics???

I think you will need one of these.

A coordinated move between two axes proceeds proportionally along each axis.

Considering your coordinates:

G0 C45.621 X5.489
G1 C-45.621 X5.43

The question is whether the mid-way point is on your straight line.
ie: C0 X5.4595
And clearly it isn't as it is at the same radius from the centre as the end-points, and it really needs to be the point C0 X3.818382083

Adding that point helps, but then the new intermediate points (C22.8105 X4.653691042) are not on the straight line either.

The only way to do this is going to be to have lots of short moves, or special kinematics.

Rather than use kinematics, you could use G-code calculations. For example a G-code loop that iterates along the line between the end points 0.01" steps and which calculates a new X and C for each point and generates a move. As far as the motion controller is concerned this will look just the same as a long section of linear G-code and will blend (or not) just the same way.

LinuxCNC doesn't know about XC arcs though.