Convert to discrete stepper drivers on Z axis

The SKR 1.4 Turbo main board I'm using has space for five stepper drivers. Typically these are used for X, Y and Z axes and the option for two extruders. As my build has only a single extruder, this meant that the fifth slot was free. As there was facility to use it and it does permit the configuration of auto Z levelling, it seemed sensible to carry out the upgrade.

In doing this, it actually turned out to be quite simple. The steps were

  • Install new 2209 stepper driver
  • Move Z2 motor to E1 slot
  • Recompile Marlin firmware with new settings
  • Test and run Z levelling
To install the stepper driver, it was necessary to remove the diag pin as I'm not currently using stall detection on the motors (and it's not really advised on the Z motors anyway). Once the pin was removed, it was just a case of plugging in the driver to the SKR board and moving the Z2 motor connection from the Z2 slot, to the spare E1 one. 

Once the hardware changes had been made, it was necessary to let Marlin know about it. This needed only a few changes to be made. Importantly, it isn't necessary to tell Marlin which connection the second Z motor is moved to. It works this out for itself. For the changes:

The first were in configuration_adv.h 

First is to change the number of Z steppers from 1 to 2

Secondly, we need to enable the Z stepper auto align function 
Then finally, we need to make a single change to tell Marlin that the Z2 Driver is using 

After this, the new firmware was uploaded to the SKR and everything seemed to go well. 

Next came the testing. 

First I ran an M422 command which extracts the probe points which will be used for the auto levelling. This gave

M422
M422 S1 X2.00 Y150.00
M422 S2 X298.00 Y150.00

Which seemed perfectly reasonable. 

So, next was the moment of truth which was to run the auto-levelling. I ran a G34 and the printer went off merrily running its levelling. Everything worked as expected and (and I accept that this may be confirmation bias) the Z moves straight afterwards did sound smoother. 

The only slight wrinkle was that the firmware upgrade had cleared the EEPROM of all of its data. However, I had taken a copy of the M501 before starting and could simply reload this and then re-run an ABL cycle to recreate those data too. 

Comments

Post a Comment

Popular posts from this blog

SKR1.4 and TFT 35 - using long file names and print from SKR SD card

Image
This is a bit of a diversion from the rest of the blog, but it's relevant as it's on the same path. I felt it might be helpful to post this as I'd tried, unsuccesfully, to find a definitive answer elsewhere so got there by trial and error.  If you have an SKR 1.4 mainboard coupled to a BTT TFT35 (NB I suspect that this will also be relevant to other combinations of MB and TFT) and want to Enable long filename support Add the MB SD card as a print source This is what I had to do to get this working. There are two areas which need to be changed  CONFIG.INI on the TFT CONFIGURATION_ADV.H on the Marlin (2.X) build This solution is based around my configuration but is likely to be more generic, I think. I am running SKR 1.4 Turbo - Marlin 2.0.5.3 BTT TFT35 V3.0.26 Change Marlin Firmware You will need to create a new build, with the following changes in the configuration_adv.h file. First, you need to enable the onboard SD card as Then, to enable the long filenames change:  Remo
Read more

Update: delayed but not forgotten

Those of you following this blog will have noticed that I've gone a little quiet for a while. This is due to a combination of factors. First, I am very busy with work at present and, secondly, I have a backlog of things which I need to print for jobs around the house. I can't print with the printer at the same time as rebuilding it. To give an update on progress: I still need to rejig the X-axis cable chains to rotate them by 90° The fanless PSU seems to be working very well indeed and makes a huge difference to the noise of the printer The foam insulation on the base of the HBP also seems to help a lot and works far better than I'd expected. Heat up time is improved significantly and excess cooling between prints is also reduced.  I have a set of Z axis pull-rods to install for extra rigidity but these need to be modded to fit the 350mm Z height.  I also really want to move to the latest version of Marlin to address a few annoying niggles which I know are present in 2.0.5.
Read more

Sensorless homing and musings on Z-offset

Image
In a perfect example of irony, I have just decided to try sensorless homing - just a few days after finally having got around to releasing my designs for smoothed endstops .  The process turned out to be quite simple. I had some spare 2209 stepper drivers as the originals had had their diag pins removed in order to use the endstops. In fact, I had desoldered these rather than cutting them and even retained the pins, so I could also have simply resoldered the pins back into place. But, as I had the spare drivers, it seemed unnecessary.  Once the new drivers were installed, there were just a couple of changes to the Marlin firmware which I needed to make.  First was a change to enable the sensorless homing and to set default stall sensitivities.  The next change was to change the Endstop Inverting to false for the X and Y axes. Effectively, telling Marlin to ignore the endstops. I compiled a new version of the firmware and then installed it to the printer. Thereafter, it was necessary to
Read more