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

Update: Mopping up

Image
Today I have been working on mopping up some tasks which need do in preparation for creating the cable looms. This latter task is now a little delayed as I've decided to make the stepper motor cables with shielded cables, just because I don't like the amount of noise which they're pumping out .  Today, I have carried out a number of preparatory and remedial processes.  Installed the ESP01 WiFi module into the TFT35 screen. I had had a number of aborted attempts at this previously (it's more than a little arcane) but this time I have managed to get it working. In practice, I may not use it that often but it could be useful in some circumstances. It does seem very basic, but it does mean that I'm not tied to a cable.  I also decided to replace the IGUS bearings on the X axis with traditional roller bearing ones. While I had the carriage apart, I also replaced the heater block, throat and nozzle.  I also upgraded the X axis belt to a high quality Gates one as I'd b
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

Imminent release: Storage trays are finished

Image
Well, after some ado I have finally completed my storage tray solution. It's in numerous parts in order to remove the significant number of supports it would have needed and the parts just slot together. The whole thing then screws into the frame slots.  It also includes clips for the display ribbon cables.  These parts... Slot together like this. To be installed like this To do this I plan to make this available for download soon.  In other news: I have had another delivery from AliExpress as Which is an automatic case cooling kit. It has a built-in thermistor and will take 24V in and be used for the case for my SKR main board. This means that the fan will only come on when it's needed - part of my silencing scheme. I'll probably replace the fan with a Noctua to help further.  Visit the main content pages
Read more