Z probe

BoA

@Jack_X Turning off also makes machine state with lost track of the position tracking, and then it needs to be re homed, so the sw could say what is the position of each axis.

What exactly is measured with this switch ??

Jack_X

I understand. As I wrote, I rarely change my head. I would like to measure immediately after the change and no more.

Switches measure the height of the Z working field.

I have heads with different nozzle lengths. I change them depending on the material I'm working on.

BoA

Do You use this switch for homing Z?

Also if I understand tthis right, I would do it a way, that constant part of carriage is used to determine Z height, and then define tools with proper Z offsets.

Also imagine that - You measured Z height, stored it anyhow, and then power off, and move Z manually and power on. Would this measurement be still correct? I think not. That is why everytime duet looses control over motors holding position it marks axes as not homed.

Jack_X

Home switch i have on top.

After each reset, i go on home switch. On the end of config.g I have 'G28'.

BoA

homing at top, and then using switch to set Z again?

As I wrote, I would do this by measuring each tool once, and define then with Z offset. Then, when selecting a tool proper offset would be applied.

M500 P31 will store z probe offset which would be always 24mm in Your case (I guess)
M500 P10 will store tool offset

and...

If You are using M500, then M501 should be at the end of config.g

Jack_X

In which file and what to change? I'm not proficient in duet3d.

BoA

@Jack_X config.g

If You home Your printer on Z high, then Z has some known value.
You can define tools by M563 in config.g and set their offset with G10:

G10 P0 X0 Y0 Z-10 ; set tool 0 axis offsets
G10 P1 X0 Y0 Z20 ; set tool 1 axis offsets
G10 P2 X0 Y0 Z30 ; set tool 2 axis offsets

with Z offset measured only once.
For example... after homing and going to Z0
carriage is at 50mm above the bed. Tool length is 45mm.

So the offset from 0 would be 5mm (printger shows Z=0, but tool is 5mm above actual 0)

Then using T0, T1, Tx to select tools offsets would be applied automatically

Jack_X

I'd rather take a measurement every time.

I have a good and rigid connection between the stroller and the headstock. But not always the same amount.

BoA

@Jack_X Now I am confused. If You prefer to measure everytime what is the point of storing the result in any form?

Jack_X

Measure each time after changing the tool. And forget about the matter (don't think if I have a T1 or T2 tool on the machine).

BoA

@Jack_X OK then, I would add M501 at the end of config.g

And try M500 P10 and M500 P31 in probe script.

Jack_X

thx,

when printing is finished, I will check