Prusa i3 Z axis not rising high enough halfway through print

I just got my new Prusa i3 to print except now this is my issue. It prints perfectly from the start, but then after about 30-40 layers the Z axis will rise, but not high enough and the hot end begins to dig into the piece, and then with each subsequent layer it just gets worse and worse. I've tried just leaving it to run like this for a while but it never fixes itself. It looks perfect up until the point where it starts messing up and I cannot figure out what the issue is.

Here are my motor specs:
200 steps per revolution
1/16 microstepping
2560 steps/mm

0.3mm hot end
0.3mm layer height

Edited 1 time(s). Last edit at 12/30/2015 08:27PM by chrispytoes.

You either have your e-steps calibration wrong or your z-steps.
What kind of lead screws do you have? The pitch is important to know.
Also the diameter of the extruder drive gear to estimate the right e-steps.
You can see calibration guides here

The other problem might be, binding on the smooth rods from very tight x-carrier belt.
Or your z-stepper current is too low and skips steps.
-Olaf

Quote
o_lampe
You either have your e-steps calibration wrong or your z-steps.
What kind of lead screws do you have? The pitch is important to know.
Also the diameter of the extruder drive gear to estimate the right e-steps.
You can see calibration guides here

The other problem might be, binding on the smooth rods from very tight x-carrier belt.
Or your z-stepper current is too low and skips steps.
-Olaf

Sorry, this is the printer I have:
[www.geeetech.com]

My e-steps are 152 which I read was correct for the MK8 extruder, and my z-steps are 2560.

Also dont run .3mm layers with a .3mm nozzle.
With a .3 nozzle .24mm should be the max layer height (80%) for good printing.

If you want higher layer heights then get a bigger nozzle DIA.

Quote
chrispytoes
My e-steps are 152 which I read was correct for the MK8 extruder

It's not that easy, you really do have to measure and check. And it will be different for each filament type and also depending on how tightly you adjust the arm, as the effective diameter changes with the depth that the teeth bite into the filament. Mine runs about 185 ish, and I compensate for different filaments with the extrusion multiplier in Slic3r.

Edited 1 time(s). Last edit at 12/31/2015 06:39PM by JamesK.

Look in your firmware for the Z_MAX position setting. This may be the soft-limit that is preventing your Z axis from rising further.

---

Master Tinkerer

Also maybe warping, causing the top to lift up and hit the nozzle.

Hi,

Although this is an old thread perhaps someone can help me with a similar problem. I have a diy Prusa i3 made with the box frame, which I built about 3 years ago. I stopped using it after about a year and have just come back to use it again.

Apart from resetting Marlin (I use marlin with Pronterface and slic3r recent versions) I have had a few problems of the basic kind, such as levelling and prints warping and not sticking etc but these are sorted. it was just like starting over again and refreshing the processes. However I have run into a problem I have not seen before and wonder if anyone has any suggestions as I describe the problem below.

Last night I started a smallish print - a small idler for a direct filament drive - and it was printing well except for an overhang but that's beside the point. I left the printer running about a third of the way through as I was called away. when I returned the print was ok up to about halfway but then the rest was squashed and distorted. This morning I tried the print again and it started well laying down the skirt and first layer but then as it printed subsequent layers the Z axis was not lifting and the printer was printing on the same level for each layer. The Z axis was retracting and lifting as normal but was returning to the same position to print each layer obviously giving no height to the print. I cancelled the print loaded a re-sliced gcode, retried and had the same result.

I can raise, lower and home the Z axis as usual I have re-sliced the stl file several times but get the same result, I have even added a G90 code to the start code to no avail. I am at a loss, I am not technical enough to read the g codes, could it be that the firmware in Arduino is messed up? or is it something else. I made quite a lot of successful prints when I used the machine originally and have made a couple of nice prints recently but this has got me completely foxed.

Marlin, Slic3r and Pronterface, Motherboard Arduino Mega 2650 with Ramps 1.4 driver. All latest stable versions of the firmware and I've not changed any voltages to the motors.

Please help if you can I'm getting to the end of my tether.

Hi Terry,

I'd recommend you start a new thread, attach the gcode and add some photos of failed prints and the Z axis setup. Run Slic3r stand-alone and look at the preview of the gcode. If that looks normal (which it almost certainly will), the problem is most likely a mechanical one (slipping connectors, binding bearings/screws) or a configuration issue (incorrect driver Vref, too high acceleration).