first layer nozzle/bed height

Hi guys,

I've been trying to print 3D Hub's Marvin and a gap of ~0.5-1.0mm can be observed in between the nozzle and the bed. Which means the first layer just won't stick.

I thought the bed might have physically shifted, so I stopped the print and manually moved the nozzle (G1 X100 Y100 Z0) to measure the height, but there was no gap. The gap only existed when I try to print Marvin. I've printed the coathook.stl, whistle.stl and another one of my own designs without any problems. So that leaves me wondering if its a problem with my Slic3r settings. What setting could possibly be causing this?

There is supposed to be a gap between the nozzle and the bed when the print starts. The height of that gap should be equal to the first layer height that was configured in the slicer when you sliced the file. That first layer height should not exceed about 80% of the nozzle diameter, so 0.4mm using the standard 0.5mm nozzle.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi,

I've checked the first layer height in the settings. It is 0.3mm. The gap is certainly much larger than 0.3mm.

Does your gcode file start with a G28 homing command or a G32 bed probing command? If so, is that command messing up the Z=0 reference height?

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi,

It starts with a 'G28; Home all axes' command. Do you think this is messing up my Z reference?

I usually 'Home' and run G32 for compensation before each print. Does G28 erase the compensation I set?

G28 will reset the z0 ,if you have it set wrong in Config it will make start hight too far from bed(or too close), i suggest u remove G28 and home it first time you start your printer.

It seems it might be the bed levelling. Large gaps seems to be visible between the nozzle and the bed in one of the corners and touching in another corner. I've tried to adjust the levelling of the bed by playing with the screws but just couldn't get the bed flat enough.

From a closer look, the triangular MDF structural appears to be a bit bent. I reckon the deformation might have something to do with it. Maybe the best fix is to replace it with the aluminium bed by Dave?

Quote
xeb
It seems it might be the bed levelling. Large gaps seems to be visible between the nozzle and the bed in one of the corners and touching in another corner. I've tried to adjust the levelling of the bed by playing with the screws but just couldn't get the bed flat enough.

From a closer look, the triangular MDF structural appears to be a bit bent. I reckon the deformation might have something to do with it. Maybe the best fix is to replace it with the aluminium bed by Dave?

If it's an Ormerod 1, then the aluminium bed support is an essential upgrade.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42

Quote
xeb
It seems it might be the bed levelling. Large gaps seems to be visible between the nozzle and the bed in one of the corners and touching in another corner. I've tried to adjust the levelling of the bed by playing with the screws but just couldn't get the bed flat enough.

From a closer look, the triangular MDF structural appears to be a bit bent. I reckon the deformation might have something to do with it. Maybe the best fix is to replace it with the aluminium bed by Dave?

If it's an Ormerod 1, then the aluminium bed support is an essential upgrade.

It's an Ormerod 2. I've been fiddling with the levelling all morning and its only just barely printing. The nozzle is actually too close to the bed now, first layer is really thin and faint but at least it is sticking. I'll consider the new bed support.

AFAIK the plywood bed support on the Ormerod 2 is OK. It's the MDF one on the Ormerod 1 that used to warp badly. But I don't have an O2, so somebody who does can better advise you.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

You said you have 1 point where nozzle touches the bed and one where it doesnt? Are these two points on the outermost(ie x=200) area? If so you might have a rod twist problem(where the Y rods are not exactly pararell to eachother) ,Erik described how he fixed it here :[forums.reprap.org]


Or i suggest getting DC42s Sensor if you dont have it already it will improve measurements and eliminate the need to fix the twist with auto bed compensation. I have some twist in my rods and his sensor fixed it for me altho it might take a bit of fidling with settings to get it right like i did: [forums.reprap.org]