Dual speed Z homing?

zapta · 17 Mar 2019, 06:17

In the reprap configurator, x,y has two homing speed setting, for first pass (fast) and for second pass (accurate).

Is there a similar thing for Z homing. I am using BLTouch with probing speed of 2mm/s but if the bed is at the bottom and need to travel 300mm up to get to the head, this is very slow.

Veti · 17 Mar 2019, 06:27

you can modify your homeall.g

whats your max speed for Z?

you can for example put in a higher speed. measure Z once then set the original speed back move down by 5 mm and do the original probing.

Phaedrux · 17 Mar 2019, 06:32

Yes you can achieve this by setting the desired speed before you do the probe move.

For instance, you can use M558 in config.g to set the speed you'd like to use for your default probe speed for things like G29.

Then you can use a seperate M558 command to set a different speed before issuing your G30. Either in bed.g (G32) or your homing macros (G28)

For example, in my Z homing section I have:

; Probe the bed
;
M558 A1 F400 ; Set single probing at faster feed rate
G30 ; Do a single probe to quickly home Z axis
M558 A10 F100	 ; Set multi probing at slower feed rate
G30 ; Probe again to get a more accurate position

zapta · 17 Mar 2019, 06:54

whats your max speed for Z?

30mm/s but this speed is not used for the z homing.

zapta · 17 Mar 2019, 06:57

Thanks @phaedrux, I will give it a try.

This requires manual editing of the sys file(s), right? No more RepRap configurator and such.

Phaedrux · 17 Mar 2019, 06:59

That's right. You'll have to get into the actual macro files. Make a backup of your base configuration. Check the gcode wiki for details on what the commands do. It's very powerful and flexible.

Mogal · 26 Feb 2021, 17:11

Wow, this took me way to long to find!
(I tried figuring this out on my own, but it wasn't happening - the A's threw me off?)
(This is my homez.g)

; generated by RepRapFirmware Configuration Tool v3.2.3 on Thu Feb 25 2021 23:00:24 GMT-0800 (Pacific Standard Time)
G91
G1 H2 Z5 F6000
G90
G1 X150 Y200 F6000
M558 A1 F400
G30
M558 A10 F120
G30

I put that into my code, and I got the dual speed I was looking for.
The problem now is, that it probes quickly once, and then slowly TWICE.

I'd like one of each please.

Thanks!

Mogal · 26 Feb 2021, 17:23

Alright sorry, I found it... the A's did throw me off.

Phaedrux · 26 Feb 2021, 17:38

@Mogal Yes, the point of the A10 is to get a more accurate reading, so it will probe AT LEAST twice, or until two consecutive readings are within tolerance.