[__Britt]

My understand was that the spindle axis was always supposed to be Z; on vertical machines like most mills and routers Z would be up & down; horizontal machines like most lathes or horizontal mills/boring machines would have it be towards/away from the spindle, which would be along the same direction as X or Y on a vertical machine.

Coming from a background in computer graphics, it seemed odd to me at first, too.

[Stutank]

G'day Planebuilder. I find Bi-directional cutting for my usage not commonly helpfull, as most of the tools that I use are not bi-directional cutting.
This, and no one has asked for it is why it is not in Ezilathe.

However, when I wish to do it (Rare, but happens), I use Ezilathe's Followpoly function, and do the work in CAD.
Draw finished profile as a Polyline.
Offset or Copy or Array the other cuts as required. Possibly truncate the Outer Roughcuts to avoid "Aircutting".
Starting at the chuck end of the finishcut, add a joining line to the adjacent rough cut, then add joining lines at alternate ends, to form 1 continuous path.
Edit all to a single Polyline, following this sequence.
In Ezilathe Select OD Turn Operation and followpoly. Select the polyline from the Polyline Select box and Check Reversed.
Settings for Rough cut and Finish cuts not used, Just Delete all cuts except finishcut.
This Should give you what you want. (For a Standard ZX Lathe).
You can use the built in function editor to rename the axis and Shift and mirror as required.

__Britt. ZX plane is Standard for common 2 axis lathe (Almost set in Stone). Cannot say I know why, XY Plane would suit me, but There you go.
When I Use my Lathe Spindle as a rotary indexing axis, I use Axis "A" as this common to Mills with a 4th axis.

[Stutank]

Planebuilder

This can be added in some form or another if required.
1) Simply enter Finish cut depth as Zero, to bypass generation of all but finish cut using the multiple cuts from cad (And adjust feed etc to suit).
2) A new function that lays out the LR RL cuts similar to the cad work noted (Arraying the cuts, and truncating as required).

Option 1 is simple, take 5mins to add to the latest version (with much other work already done). Option 2 more work, but not too bad.

[planebuilder]

I drew the toolpath as you said and joined the lines, saved it as a DXF. When I open it in Ezilathe the lines are no longer joined, no problem on a simple part, I just manually selected each line in the DXF Processing window. Don't seem to be able to drag a window around an area to select all contents at once. It creates Gcode with the X values +, (because it only allows me to select lines on the +X side?) so I edit in notepad, replace X with X-. and deleted the rough cut code.
It also gives some random moves in air?? I can delete those, but it may become tedious in large codes.
I tried suggestion "1)" , when I put 0 I get the popup " Required Value Missing, (White Edit Boxes)".

[Stutank]

Planebuilder. Sorry it did not work for you, I assume you have a fairly recent version of Ezilathe. Last Upload (as beta) was V1.6.4.4, and this has all the features needed.
The ability to load Reversed Polylines was not in the last full upload V1.6.4. if you are using this version, you will need to make certain that polyline direction is correct in the DXF.

First Make sure you are set to "OD TURNING OPERATION" and for Direction "Follow Polyline". This will only work when set like this (refer included jpg).
To load as a complete polyline, it is required to select via the "SELECT POLYLINE BUTTON". This button is only enabled when the DXF file includes a valid Polyline.
The Dialog box that opens (as per included Jpg) will allow you to tick the checkbox for "Reverse Polyline" (V1.6.4.4) and then Select the Polyline required.
Once all selected, Press the OK Button to exit the dialog box, and the whole polyline should now be selected.
Selecting on screen will only select or De-select single entilies from within the polyline.

When processed you will then be able to delete all the rough cuts leaving just the finished cut, that should be all you need.

Attachment 426792