Z axis - gaps between layers

I have a problem with my Z axis (prusa with RAMPS 1.4, Marlin).

When I print the first layer seems to be Ok - after that however the Z axis seems to increase in steps that are too large to correctly lay down the next layer so it ends up looking like I've printed a shredded wheat rather than a cube (I've also tried other files and ended up the same).

I've moved the z-axis in Pronterface and measured it and it's been pretty much spot on when I've measured the distance travelled.

Any ideas appreciated.

What layer hight and what nozzle size are you using ?
Have you calibrated the extruder?

I would check that all 3 jumpers are under the driver and also check the Z step value in Marlin.

Thanks guys

Hmm , it appears to be an extrusion issue.

No matter what esteps value I change to (via marlin - and checked with pronterface & repetier to make sure it is updating) the extruder pushes though around 180mm for every 100mm it's asked to. It's off - I've checked the board and everything seems ok on that.

I also seem to be getting the occasional knocking noise from the extruder.

Craig

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ss002d6252
Thanks guys

Hmm , it appears to be an extrusion issue.

No matter what esteps value I change to (via marlin - and checked with pronterface & repetier to make sure it is updating) the extruder pushes though around 180mm for every 100mm it's asked to. It's off - I've checked the board and everything seems ok on that.

I also seem to be getting the occasional knocking noise from the extruder.

Craig

If you have eeprom enabled, be sure and clear it out. I spent several hours trying to tune my machine only to find that a value I'd previously stored in eeprom was overwriting my attempts to change params in the firmware. I ended up disabling the eeprom in marlin since it is easier to just flash new firmware values than to tune via eeprom.

Quote
hoxsiew

Quote
ss002d6252
Thanks guys

Hmm , it appears to be an extrusion issue.

No matter what esteps value I change to (via marlin - and checked with pronterface & repetier to make sure it is updating) the extruder pushes though around 180mm for every 100mm it's asked to. It's off - I've checked the board and everything seems ok on that.

I also seem to be getting the occasional knocking noise from the extruder.

Craig

If you have eeprom enabled, be sure and clear it out. I spent several hours trying to tune my machine only to find that a value I'd previously stored in eeprom was overwriting my attempts to change params in the firmware. I ended up disabling the eeprom in marlin since it is easier to just flash new firmware values than to tune via eeprom.

Thanks - I've tried flashing the new firmware each time to make sure when I've played around with the settings.

What I've noticed is that it's moving about 2mm on the z axis for each layer whilst printing (I measured it with a gauge) yet when I manually moved the rods a set distance through the software it was dialled in almost perfectly when I measured it.

If I can get the z-axis problem sorted I should be able to sort the rest

If i understand it right, when manual moving in proterface or repetier the distance off travel is correct? In that case your esteps are set ok.
Have you set the layerheight in slicer at 2mm or 0.2mm?