Tuning home position: Z-0.5 is maximum

[wattronix]

I am trying to set Z home for the first time. As I instruct the bed rise 0.5mm at a step using the Machine Control of DWC, once I try to go from Z-0.5 to Z-0.55 or Z-0.6, the head refuses to go up such that I can slowly find the level where the nozzle touches the glass plate.

Suggestions as to how to overcome are welcomed.

[michaelarmani]

There is a small amount of backlash due to tension in the belts and gravity that has to be considered. In a fine tuned system, the belts are all tight, the pulleys are checked that they are flat on the shaft and tightened, the Z sliders on the rails are lubricated and smooth to give low friction, and extra weight is added to the bed such as thick glass to ensure gravity helps absorb backlash. Even in such a system there will be no less than Z = 0.10mm backlash. Please identify your backlash (it could be in the range 0.1-0.3mm usually). From here, use this when doing calibrations, or Z-hop during prints.

[wattronix]

Hello Michael,

Thank you for the response. I measured the shortfall with some feeler gauges and inputted the value.

I moved on to Set up the bed probe and assumed that the statement “Engage bed probe” was the title of the photo below. It was an in reality a not well placed instruction to lower the bed probe. Not knowing what the G30 referred to, the bed forced its way into the nozzle and jumped down about 10mm.

Realizing the error, I homed the bed and restarted. Going thru the correct procedure with the probe lowered when required, the bed now stops quite far (~5mm) away from contacting the nozzle. The bed Z position comes as high as Z-0.5 and will not rise further when I activate the Move Z buttons, as instructions dictate, to move the bed up to contact the nozzle. I should be having a reading for Z at this step to about -7.0.

Hoping you can guide me further.

Ron

From: Michael Armani notifications@github.com Sent: Friday, September 27, 2019 4:19 PM To: PrintM3D/Promega Promega@noreply.github.com Cc: wattronix wattronix@hotmail.com; Author author@noreply.github.com Subject: Re: [PrintM3D/Promega] Tuning home position: Z-0.5 is maximum (#53)

There is a small amount of backlash due to tension in the belts and gravity that has to be considered. In a fine tuned system, the belts are all tight, the pulleys are checked that they are flat on the shaft and tightened, the Z sliders on the rails are lubricated and smooth to give low friction, and extra weight is added to the bed such as thick glass to ensure gravity helps absorb backlash. Even in such a system there will be no less than Z = 0.10mm backlash. Please identify your backlash (it could be in the range 0.1-0.3mm usually). From here, use this when doing calibrations, or Z-hop during prints.

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[michaelarmani]

You are correct, Engage probe was meant to indicate the user manually deploys the probe.

By hitting the nozzle, you've got the machine thinking it is inside the nozzle, then when it fell back ~10mm it thinks it is way off course - there is a "software endstop" that protects the nozzle from Crashing into the bed once calibrated.

To bypass this, try your procedure again but first put in this gcode command into the web interface: M564 S0 H0, or you should be able to restart the printer (power cycle the blue-lighted switch for about 5 seconds off then on).

At the stage you are at I think you would be best served looking at the Duet documentation and talking amongst the other users in the discord or with our tech support team as the Github should be used to improve the code set if there is a systemic issue. Please visit https://discord.gg/eQ5wPwk for the community or http://support.printm3d.com/

[ftcros]

When I was first setting the Promega up I frequently had lag after issuing a command. I then got a screen popup indicating 'connection lost - wait for re-connection' meaning the network IP had lost its connection with the printer. I'm still trying to resolve this problem and have tried a 'static' ip with and without MAC code (\sys\M540 in machine_access.g)

M540 PBE:EF:DE:AD:FE:ED ; Set MAC address, this can be used to assign a given IP in the DHCP M552 P0.0.0.0 S1 ; Use this to enable DHCP ; M552 P192.168.1.122 S1 ; Set Static IP address and enable networking

(; M552 P192.168.1.122 is the IP assigned by my DHCP so I incorporated it in the static IP - but still have times when 'connection lost' appears). At present I'm using DHCP with MAC address but I'm also considering using a USB/RJ45 3.0 adapter to connect the printer directly to my PC.