Axis - add 2nd Rotary axis - GEOMETRY?

Running LinuxCNC 2.7.7

Before (Running fine) 3 axis CNC lathe CXZ - No "Y" axis but simply rotating C gets me there.(Think polar coordinates)

After (Need help with display): add 4th rotary axis "B" (Rotates around "Y") to change the angle of the router bit. When i use CXZB - and issue a G0 B270 the tool rotates around Y and is aligned with the "X" axis - pointing to the center of the workpiece. Awesome. Then when i rotate "C" the bit is still oriented in the same direction. the tool stays aligned to the "X" axis but does not "point" to the middle of the workpiece. Physically the bit does stay pointed to the center of the Z axis unless I enter another G0 Bx command.

I know this is not making sense - the physical operation of the machine is correct but the AXIS display does not respect that changing "C" does not move "B" relative to the "Z" axis (i.e. B270 orients the bit perpendicular to the "Z" axis. B0 orients the bit parallel to the "Z" axis.

I have tried BCXZ, CBXZ and CXBZ with no luck.

I do have this setup in a simulator to test.

Thoughts? suggestions?

This is what i have currently (Does not work as expected)
later on i have this:

ok - I tried the following combinations:

BCXZ, CBXZ CXBZ and CXZB

The latter rendered a CXZ series of moves correctly in the XYZ planes while the others simply did not.

In the last combination if i JOG the B axis the "bit" representation does rotate around a point correctly but when i then jog the C axis the point moves around but the bit does not change orientation. if the B angle is 270 at C0 it should be parallel to the X axis but at C90 it should be still perpendicular to the work piece since the work piece simply is rotating around the Z axis. so in one respect the "Bit" stays parallel to the X axis in the real world but as the work piece rotates the "Bit" stays perpendicular to the outside of the work piece

Here is my setup again:

It is a CNC Lathe: with the following axis:

C Axis - Rotary axis rotating around the Z axis - there is a chuck on the C axis that holds the work piece and rotates it to simulate a "Y" axis
Z Axis - Linear axis that moves the router bit between the headstock and the tailstock parallel to the ways
X Axis - Linear axis that moves the router bit perpendicular to the Z axis with 0 being the centerline of the Z axis

I am adding a rotary table under the router that moves in the ZX linear axis that allows the bit to change its orientation relative to the work piece. it will rotate around the "Y" axis which is why i selected "B" for the axis name.

Before I added the 2nd rotary axis i used CXZ as the geometry and it rendered great!

I hope this makes sense.

I do have a SIM setup this way and am attaching the relevant files.

NOTE: There are two NGC files - probewireCXZ.ngc and probewireCXZB270.ngc to check rendering.

Any assistance is appreciated.

OK - An update
When i add "LATHE=True" to the display section the geometry all works correctly. the CXZB displays fine.the "Bit" is oriented correctly based on the "B" axis angle.

however, i now have lost my 3d rendering (ability to move the rendering in 3 dimensions. Is there another option I can set to get back the X/Y/Z and pan icons?

Thank you!

OK - i am wrong. When i setup the B angle to -43 degrees when the plot is at C angle 0 the orientation is correct. As the "C" access rotates by the time it hits 180 the orientation of the "tool" has moved to +43 degrees. Oh well.

Maybe it is time for me to get under the covers of the AXIS code to try and decipher what is going on....

ok - so just for fun i tried all 24 combinations of XZBC to see how they would work and only 3 combinations actually rendered CXZ appropriately - none did the B axis "tilting" the bit as i would like. I am going to start looking at the code but before i do i have a question:

If i did a custom Kinematics module for XZCB - would that make any difference to Axis?

Also, is there a developers guide somewhere for how the py and .c modules are orgainized? i did follow the directions and was able to setup a development environment, compile everything and run the test routines successfully.