Common Z-Offset Practice Differs From Print Reality

I notice when I set my z-offset on a TAZ 5 using a common industry practice outlined below that in reality when I go to print something the nozzle is always too far away from the bed so I need to further lower my final z-offset using test prints as my guide.

It’s like the printer has a different z-offset depending upon whether only the x-axis is being lowered vs when it is actually printing. Perhaps other TAZ’s suffer from this phenomenon? Has anyone else noticed this phenomenon?

Common Practice For Setting Z-Offset (Ends Up Requiring Tweaking via Real World Test Prints)

  1. Home printer.
  2. Move nozzle to center of the bed via LCD or G1 move commands in Pronterface.
  3. Lower nozzle until I can feel slight resistance when sliding a piece of paper between nozzle and bed.
  4. The resulting z value (as discoverable by M114 in Pronterface) is the z-offset that gets stored in EEPROM / Firmware to be used by the printer.

As you have described, the Z-offset is used to fine tune the location of the first layer. I’m going to guess that the initial z value you measure and store and the final z-offset after your test print adjustments differ by the same amount (or the same amount per filament type).

If so, you can skip the test prints (or reduce the number of them) by applying this constant to your initial, paper measured, z value.

b-morgan thanks for your reply. First I measure z-offset using the paper slide test then store it in EEPROM / firmware and do a test print. The test print always tells me I need to further lower my z-offset. They are never the same values.

The measured z-offset using the paper slide test is always too high based on test print experience. It sounds like you never have this issue. Maybe it just occurs on my TAZ?

I don’t have the issue because I have a TAZ 6 :crazy_face:

Have you attached a bed probe of some sort to the Taz 5? Stock Taz 5 uses a screw on the LH side of the printer to adjust the first layer squish. Z offset should be 0 if it is available in the Marlin menus.

On a stock Taz 5, you will notice the nozzle is closer to the bed when the toolhead is in the center of the X axis than it is at the left or right sides of the x axis. This is due to flex in the x axis rods. You just have to find a happy balance with this printer. Tight enough at the edges and not too tight in the center of the bed.