Hi guys, yesterday I've tried couple of prints on my printer and found out that the printing always starts about 1.25 cm above the glass on the heated bed. The home position for z axis is set to be approximately 0.2mm (1 sheet of paper) above the glass however as the printing starts the z axis homes and then moves 1.25 cm above the right hand corner of the heat bed and starts to print. Obviously the filament doesn't stick and just blobs on the nozzle. I can't set the homing position any lower as the nozzle would be scraping the glass already and wouldn't be able to home. Any ideas how to fix it ? I am using ramps 1.4 with marlin firmware and for the actual printing I am using slicer to generate the g code and pronterface for the actual print. I've tried three different stl files to eliminate the possibility of a bad command in the gcode. Any advice would be appreciated.

Sounds like you've got a home offset value set. Send the following to the printer to remove the offset for the Z axis:

M206 Z0

Offsets may be stored in EEPROM - send M503 to see what's been stored. Check the reprap wiki for further information. [reprap.org]

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I tried that and it seems that thats not an issue i got this as a response ''echo:Home offset (mm): echo: M206 X0.00 Y0.00 Z0.00'' . Any other ideas ?

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Stalker
Hi guys, yesterday I've tried couple of prints on my printer and found out that the printing always starts about 1.25 cm above the glass on the heated bed. The home position for z axis is set to be approximately 0.2mm (1 sheet of paper) above the glass however as the printing starts the z axis homes and then moves 1.25 cm above the right hand corner of the heat bed and starts to print. Obviously the filament doesn't stick and just blobs on the nozzle. I can't set the homing position any lower as the nozzle would be scraping the glass already and wouldn't be able to home. Any ideas how to fix it ? I am using ramps 1.4 with marlin firmware and for the actual printing I am using slicer to generate the g code and pronterface for the actual print. I've tried three different stl files to eliminate the possibility of a bad command in the gcode. Any advice would be appreciated.

0.2mm is too big for the nozzle gap. A piece of photocopy paper is 0.1mm, not 0.2 so what paper are you using? Also, you should be able to set you nozzle to between 0.05 and 0.1mm without touching the glass. If it does, then your bed is not level.
Do you really mean 1.25cm above the heated bed when the print starts - that's 12.5mm!
Can you post the g-code of a file that this is occuring with?

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Waitaki 3D Printer

I managed to fix the problem. It seemed to be in slicer as it entered the command to lift the nozzle for heating after the command for homing. The printer homed then it heated up the bed and then it lifted the nozzle to heat up. However it never made it come back down. So I switched the order of the gcode and I home the axis after the heating and then it starts to print correctly. And for the gap I am using standard papers for office printing. So the gap may be actually 0.1mm. I sprayed a thin layer of hair spray on the glass and tried to lower the nozzle even further as I can imidiately see when it touches the glass but I am unable to do the fine measurements as I lack proper tools. The bed is perfectly leveled I checked it with spirit-level.