Homing to sides of workpiece with real tool How? Lathe

How about posting a screen shot also which boxes are you entering the data in?

The home position can be anyware you like it does not have to be at the edge of the stock and I believe that is G53. Then when you touch off it become generally G54

which version of Lcnc are you using


linuxcnc.org/docs/2.7/html/lathe/lathe-user.html

How I do it.

Home the machine - as I have no home switches I generally move the x axis z axis to mid travel and home there. (with x being approx=0 = the spindle axis)

Mount the tool you wish to use.
Using the MDI window, enable that tool with a Tx M6 where x is the tool number.

Take a small test cut by manually jogging the machine in x to get a small cut and then jogging in Z, Jog back out in z leaving x unchanged and measure the resulting diameter

touch off the x axis (not tool touch off) and in the input box enter half the measured diameter (assuming you are in radius mode rather than diameter mode)

The on screen coordinates for radius/diameter should now reflect the measured diameter too as a check.

Having tool offsets in the tool table is only of value if you can change tools with the new tool being loaded in a known location - eg by using a quick change tool holder with a separate holder for each tool, or by having some kind of touch off switch that can measure tool offsets on the fly.

Another day of struggle...

I can only use it as follows: Not ideal.
3mm half round tool as earlier.
1) move X in until it touches OD of blank.
2) Home X.
3) remove workpiece.
4) Move X in by 1.5mm on CNC coordinates.
5) Home X again.
6) Workpiece fitted.
7)Move Z left until tool touches face of workpiece.
Home Z
9) remove workpieve
10) move Z left 1.50..
12) Home Z again.
Done.

So now the tool centre will sit on 0,0 is on the worpiece corner.
When putting the yool on 0,0, it's centre would align with the worpiece corner. But of course it can't move there as the worpiece is in the way
Surely this must be possible to set with the touch of or offsets somehow?

I have not managed so far.

I assume you have looked over the Lathe documentation. The control point section is helpful.

linuxcnc.org/docs/html/lathe/lathe-user.html

Also, machine home is different from part zero and you are not homing the machine to the part. I think there is some confusion there. Usually machine home is away from the chuck.

You also need to load the tool offset by issuing a G43.

T1 M6
G43

Deleted .see next...

Re re reading that lathe text...

Major point of confusion:
The touch off there works off the tip of a tool. ie machined workpiece diameter.

Assume Round tool orientation 9.

The described method is actually ignoring cutter compensation.
It results in the outer tool radius being the tool reference instead of the tool centre.

And that is my problen.

Any further machining with cutter comp on now results in the tool running incorrectly.


Documentation. Section 4. Z axis point 6 states:
"Select Touch Off and pick Tool Table and set the position to 0.0."
What is meant here and which window? I cannot figure it out.

Below point 7 then:
"If you have a 0.125" wide parting tool and you touch the left side off but want the right to be Z0, then enter 0.125" in the touch off window"

Which window exactly? And the at what point is this offset active?