Z Axis - Marlin "Baby Stepping"

All of the early Robo3d printer owners had the Z Axis stepper motors “disabled between moves” parameter set in the Marlin firmware configuration.h data. This made it easier to “adjust” the threaded rods by hand during printing of the loops and first layer. Many users have come to rely on “twiddling” their rods as a way of getting the first layer down as cleanly as possible.

A far more convenient way to “twiddle” your rods accurately and without getting your hands dirty is to use the “baby stepping” function already built in to Marlin.

“Baby Stepping” is a Marlin firmware feature which allows the Z height to be adjusted ustep by ustep up/down on the fly directly from a LCD controller turn and click knob. The function is very powerful but does not seem to be well known (eg search of this forum shows only one mention). And surprisingly, the feature is not enabled in the standard Robo firmware either.

I've attached a short doc outlining why Baby Stepping is so useful for tweaking the first layer and how to set it up on your Robo.

As always comments and suggestions for improvement very welcome.

 

Great contribution! I think we should drop this into Melody's FAQ.

 

I think @Ziggy is the source of all things cool for mods. This is probably the best one.
But there are plenty of 'stock' things you can do with the LCD. browse through the menus and play around. You can't really hurt anything. It all resets when you cycle power unless you update it in the firmware.

 

I presume this means that the print gcode must be coming directly from Simplify3d - not the SD Card. Is that correct?

 

Yea, I think this only would work if you are doing a direct print, not the print from SD...although you can (somehow) flip back and forth so I might be off-base. I don't use a fraction of the features. I have the philharmonic orchestra on stage, but I am only directing the tuba player...

 

I've updated the Baby Stepping notes to include a mod which shows the number of Baby Steps on the LCD display.

Without this display it is difficult to keep track of how far the baby steps have moved the Z axis up or down.

The mod has been tested with the REPRAP DISCOUNT SMART CONTROLLER and the REPRAP
DISCOUNT FULL GRAPHIC SMART CONTROLLER

 

On the finest setting each baby step is 1.25mm/2560 = 0.000488mm. So you need ~205 baby steps to move the Z axis 0.1 mm. That's a lot of twiddling on the encoder knob.

There is an option in the configuration_adv.h file to scale up the number of stepper motor baby steps for each turn of the encoder.

#define BABYSTEP_Z_MULTIPLICATOR 1 //faster z movements

 

Mike. It works fine with auto leveling. But just hard to see as the auto level z movements swamp the baby steps.

 

@Mike Kelly is the best person to answer this question. There are many versions and some have important functions missing (eg M565 gcode). So best to get the correct version via Mike.

There was another post recently with a similar LCD problem. I suspect it is a hardware issue caused by intermittent cable connection(s) to the Ramps board or LCD Controller or possibly the cable connectors themselves are not making good contact with the flat cable. It may also be a problem with the pin connections between the Ramps and the Arduino mega board.

I suggest you unplug/replug all the LCD cables and connectors ( gently a few times). Hopefully this will improve the connections.