Have had someone such a problem?

Hi all,

I use self made printer like THIS. It is with Arduino Mega 2560 + RAMPS 1.4 + 5 * A4988. I use Repetier Firmware 0.92.3 and Repetier Host 1.5.

3 days ago I printed normally.
Without changing almost anything, I noticed that the print have a problem - it shifts on the bottom part by "Y" axis.

Yesterday I made 3 tests. The object for print was 20 x 20 x 20 mm "cube" with 2 mm thick shell and missing TOP / BOTTOM side.

The first try was sliced with Cura Engine.
The result was: THIS

After than I decided to scale X Y to 10 mm and leave the Z as is - the object! Again sliced with Cura Engine.
The result was the smallest object in front - HERE.

At the last I decided to change the slicer - I tried with Slic3r. And the result is THIS one in front..

The pictures are not good enough, but trough a magnified glass I can see that the first 2-3 layers are OK. Than the shifting begins and continues 15-16 layers. After than the print is absolutely vertical - OK. And the "effect" occurs on the all 3 prints no matter of size of the object and the slicer !!!

The first think was that the pulley of Y motor is not tightened enough, BUT the motor arrived with the pulley heavyset on the motor axis. There is no way to "move".
I tried to tighten the belt too with heaviest springs - without result.

I think that the problem is not mechanical or electrical, because nothing was changed from before and because if it IS, the shifting have to occurs on different layers. Here we have a constant repetition of the defect.

Have had someone such a problem? All ideas are welcome !!!

PIC1 ; PIC2 ; PIC3 ; PIC4 ; PIC5 ; PIC6 ; PIC7

Thous are the GCODE files...

10x10x20_Slic3r , 10x10x20_Cura , 20x20x20_Cura

Looks like belt or pulley slippage or stepper motor losing steps due to too low current.

Ok, but why every time on the same place (~15 layers) and after than all is OK ???

Hello,
did your Y axis hit another piece? Check the cables, if they are long enough... Did your hotend collide the printed part during the print?
Generaly the axis slipping may be due to the low power on stepsticks, a deficient stepstick or motor. But in your case you only encounter the problem on the first layers and are exactly the same...
I suggest you to decrease drastically the speed, and look what happens during the print.

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Prusa i3 - e3d v5 - Gnu/Linux - Pronterface - Slic3r - Octoprint - Rpi - French

The Y axis moves without problems. The Print speed was every time low enough. The Y motor is big enough, and it is warm enough. I'll increase a little the current of this motor and will check, but think this is not a problem.

I do not use cooling, because the print quality becomes bad... That's why after first 2 layers I decrease the bed temperature to 90°C and all is (was) perfect....... until 2-3 days ago when I noticed the shifting.

What I did today:

Re flashed firmware.
Checked tightening of the pulley - PERFECT.
Checked symmetry of the pulleys and the belt - almost perfect.
Checked many times for possible step loosing - the motor do NOT loose steps.
Checked current for the motor driver - VREF = 1.57 V, that have to mean: 3.925 A - the absolute max for this driver ( ±2 A)
The driver temperature is 27-30°C, the motors temperature is 28 - 31°C.
Max speed for this axis is limited to 90 mm/s .

Tried new print with other layer high and variable feed rate:
Even on 50% of the feed rate the printer shift layers at the SAME Place (layers) as yesterday !!!
When the "problem" layers were passed and the printer started to print correctly, I tested with 150% feed rate - perfect layers without shifting, without step loosing.

So, the last that I'll check tomorrow will Uninstall and Re install the host and all settings.
May be have to test with another host - I'll think.

Edited 1 time(s). Last edit at 07/09/2015 11:02AM by DBS.

Where did you get the stl file from? Have you tried printing a similar object from elsewhere?

When using CURA, load the object select the "View Mode" icon on the top right of the screen, select the "Layers" option and scroll through the print layer by layer to see if the layer shift shows up.

I made the STL by my self, using CAD software. And I'm sure the file is OK.

Every time I check almost all layers to see what really I'll print. So, the problem is not in the file - believe me...

For the first time the problem occurred on a printed for the second time a part that was printed a day before and all was OK. Every printed part after that has shifted layers in this field.

I'll try with another host tomorrow....

Edited 1 time(s). Last edit at 07/09/2015 04:01PM by DBS.

Quote

Checked current for the motor driver - VREF = 1.57 V, that have to mean: 3.925 A - the absolute max for this driver ( ±2 A)
The driver temperature is 27-30°C, the motors temperature is 28 - 31°C.

I'm not aware of any A4988 that can deliver 4A, nor would many nema 17 motors require that much current. How did you measure the temperature of the driver and motor? Something does not seem to add up here.

Hi all,

I couldn't check with another host program, because of flashed firmware - it has some limits.

I re-made the firmware and re-flashed the arduino mega again, but situation is the same.

You can see HERE the result I think that the shifting is from 0 to ~ 5 mm (on Z) and after that all is OK.

It is seen from the pictures that the problem is NOT mechanical nor from the motor driver.

Meanwhile I have installed the versions: 1.50 and 1.52 of the Repetier Host - nothing changed.

Tomorrow I'll connect one notebook as a management PC and will report.

Agreed, that doesn't look like a stepper driver problem. Could you try printing with the heatbed turned off altogether?

what kind of pulleys are you using on the y axis stepper motor? aluminium or printed? if printed what material?

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@JamesK

The material will not stick to the bed without heating it.... But the shifting is not from the bed temperature - I'm sure. Before I had such issue with "bending" from the heat from the bed and it is quite different.

@thejollygrimreaper

The pulley is from brass and ABS (I guess). It is factory-made and is very firmly attached to the axis in the factory. I can not pull the pulley from the axis without destroying it.
If the problem was with tightening of the pulley, than shifting have to be on different places - not only from 0 to 5 mm (by Z).

The problem is not too from the slicer - I can publish the .gcode file(s) and every one can check it (them)

This is something between the PC and The Arduino Mega...

So,

Bran NEW and FRESH installed Windows 7 Ultimate 64 bit, + Arduino IDE 1.6.3 + Repetier Host 1.5.2 + New slicers + NEW interface (US cable.... Again from 0 to 5 mm shifting and after than OK.

Before that CHANGED Driver for this axis (Y) - without changes

The last that can be problematic is the Arduino Mega 2560... Unfortunately the new one purchased is on the way.
Meanwhile I'll search for the way to do real (total) reset of the board. May be I have to burn a new Bootloader...

Your vref is far too high. As it heats up, current flow will drop, and move toward a region that is better for your motors, thus the upper part of the print is better.

That would be my instinct given the info above. Reduce your vref to correct value for your motors after doing the math.

I might have been inclined to suggest a mechanical problem, but the shift is far too consistent. Stepper driver issues can be surprisingly consistent

@Mutley3D

Thank you for the advice. I'll check it tomorrow.

Could the problem be with your extruder? Could it be twisting (or untwisting) as it rises.
For example, could the wires to the extruder be too short so that when it is at its lowest position, they are pulling on it and lifting it? Or could there be some obstruction so that when the X-axis is at its lowest position, there is something pushing up on the x-carriage and forcing it to twist a little?

I set all Vref's of all drivers. Now they are max 10% more than by motors specs. This didn't help me.

@blabbersnitch

No, The Extruder lies on X axis and it is so made the twist is impossible.

I'm 99.999% sure that the problem is in Arduino Mega 2560. First because the problem occurs incidentally and second, because it is the last part from the puzzle that is not changed yet. But I have to wait the arrival of the new one.

Edited 1 time(s). Last edit at 07/12/2015 11:02AM by DBS.

Quote
DBS
I set all Vref's of all drivers. Now they are max 10% more than by motors specs. This didn't help me.

whats the model number of the stepper motors?

can you post a photo of your ramps board , and a few of the printer ?

also why 10% above the rated current, all thats probably doing is helping to make the situation worse by making the stepper drivers hotter and more likely to loose steps by going into shutdown due to heat

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I changed everything in my setup, except mechanical components (because they are the same as before the problem). i.e.:
- PC (from Desctop to Notebook) + the host software (different versions of Repetier Host - from v.1.06 to v.1.53)
- USB cable
- Arduino Mega 2560 + few times new firmware (Repetier 0.92.3)
- RAMPS 1.4
- Y driver (A4988)

In addition I made some changes in my firmware too, especially STEPPER_HIGH_DELAY 1 (from "0")

I checked many times the current from the drivers and theirs (and motor's) temperatures. They are as follow:

Axis - Driver - Motor
"Y" - 32.7°C - 31.5°C
"X" - 28.0°C - 32.4°C
"Z1" - 35.5°C - 34.7°C
"Z2" - 28.5°C - 32.4°C
"E" - 28.0°C - 31.8°C

All temperatures were measured with digital infrared thermometer and the ambient temperature was 27.2°C.

The Vref of the "Y" axis was 0.8V but the motor has left some steps. That's why I raised the Vref to 1.00 V and now it works smoothly. The temperatures quoted above are with Vref = 1.00 V. !!! Before the problem, Vref was even more high - 1.52 V, and I had NO any problems for more than a year !!!

The last, that can be changed is the firmware type. Because I use from many time Repetier's firmware and miss the development of the Marlin's ones, can someone to advice me which version is good for "cartesian" (Mendel) printer, very similar to THIS ??? The most important for me is to save the option of Bed Leveling!!!

Thank's to all