I'm just moving to smoothie from the typical ramps setup with Repetier.

I’m just moving to smoothie from the typical ramps setup with Repetier. Just started to research stuff and one of the things I could not find is the ability to change the z position while printing. Called babystepping in marlin and Repetier. It’s huge time saver when I change nozzles - I don’t need to measure the new z offset from the bed and can basically adjust the first layer on the fly.
Can someone point me in the right direction…

No baby stepping in smoothie as far as I am concerned. Lots of probing options though.

Hmmmm. How do others handle this situation. Do you level the bed and adjust the Z offset every time you change a nozzle? Or is it that I’m crazy and change my nozzle size too often?

It’s been a while, but bumping Z while running a program certainly caused me some really odd results. I was going to suggest reprobing but that’s not going to work right if the probe height doesn’t change with the nozzle.

@Wolfmanjm We don’t have this, right ?

@Dushyant_Ahuja I’m not sure what hot end you are running, but I change nozzles quite frequently on my smoothied-herculien (I have both an e3d and volcano on the same carriage). The variation in z-offset is so minor that I don’t even bother adjusting my z-height at all. However, I can see a potential problem if you were trying to put down a first layer with a height of 0.1mm or less. Running a first layer height of ~0.2mm I haven’t had any problems to speak of.

@Zane_Baird the main issue I have is when I change the volcano nozzles to the normal ones. That’s a huge difference due to the different sizes of the heated block. I guess I need to do things properly now. Repetier had allowed me to be simply lazy. Unless @Wolfmanjm can add something quickly. Pretty please :slight_smile:

@Dushyant_Ahuja Ah, I see your problem. You can always just fix this with a z-offset change in the starting script of your slicer. However, this would mean you would need to set your z-axis to home to the maximum to avoid crashing into the endstop or crashing the nozzle into the bed (depending on whether switching from the volcano to the v6 or vice versa). Should be relatively easy if you properly tune the offset to account for the differences in hotend length

@Dushyant_Ahuja Zane is giving you the right idea. Here’s what I suggest.
Get a proper probe on the head so that you don’t have to move your endstop constantly. Otherwise you’d need to get a optical endstop so that you can go through it (below) without crashing. I’d do that so you can still use a min endstop. Then you use the Z offset in slicer. For example, the volcano is 8.5mm taller than the v6.

@raykholo @Zane_Baird thanks for the suggestions. Like I was saying, it was just a lazy man’s way out. I have a glass bed, and have recently ordered a capacitive probe. Let’s see how that works.
I had tried an inductive one with aluminum tape on the bottom of my glass plate - but that did not give me good results. Let’s see if this works.
I also have optical endstops that are yet to be incorporated into the printer. Just plain lazy.

@raykholo the offset would also depend on how much the throat goes into the heat sink. So every time I change the heater block - I would need to measure the new Z offset. Not difficult, but having the ability to babystep was just plain easier. My LCD screen is primarily used for that - as I have an octopi setup for the actual control. Well - you win some and you lose some.

@Dushyant_Ahuja The amount of insert into the heatsink should be very reproducible assuming you screw the two together tightly (to spec, hand tight) as this will create a flush fit with the heat brake and the heat sink. Because everything on the e3d hotends fits together flush in z, you end up with a fairly reproducible offset

Well - on a Chimera the heatbreak is used to adjust the height of the two nozzles so that they are level. That causes some uncertainty in the actual offset. Again - not difficult, just inconvenient to what I am currently used to.

@Dushyant_Ahuja Didn’t realize you were using the Chimera… That does complicate it a bit, even with a probe.

Back in the day I built a 2’x4’ printer with dual chimera and a basic z probe (switch on a servo)

Oh, so I just stuck all the chimeras in the uppermost position (thus putting the nozzles into a straight line) and using the left/right leadscrews to align them parallel to the bed. Probe took care of the rest.

We do Z offset correctly like all CNC machines do! No need to give it a special name like baby stepping or whatever. You can change Z offset on the fly with workspace coordinate system… G10 L2 P0 Zxxx where xxx is the offset you want. works immediately

@Wolfmanjm thanks - will look into the workspace coordinate system. Is there any way to adjust this using the knob on the LCD.

No not really.

could you use a the Switch module and have it execute something like:

G91 G10 L2 P1 Z-.01;

and then

G91 G10 L2 P1 Z.01;

tie those two commands to the dial

I don’t think it would work well unless the print was segmented. And I have no idea how the look ahead buffer would effect something like this.

Just spit balling a bit.