Print jumps 7mm in Y direction after initial layers

[printbus]

Doing a quick ebay search, do the Kysan steppers you bought from ebay have the Kysan branded sticker on them? There seems to be two, one without this sticker and one with.

I bought one from the 3dmakerworld seller. Their picture doesn't show a Kysan sticker, but the motor came with one. Although I do have to chuckle - it looked like a label anyone could have printed and stuck on the motor.

These motors all tend to look the same, but one obvious thing about this one I found impressive is the wire gauge. It's marked #22, compared to the #26 wires on the OEM motors from MakerFarm. Heftier wire should mean less resistance, leading to more power being applied directly to the motor. I'm not sure that difference in the motor specs alone would have justified the increase in wire size for the Kysan.

[old man emu]

There isn't an M906 command in Marlin. But there are these two commands:


case 907: // M907 Set digital trimpot motor current using axis codes.

case 908: // M908 Control digital trimpot directly.

C'mon! Giving an answer like that is like starting the Dance of the Seven Veils and stopping at Veil #1.

Please to explain how honourable code work.

OME

[Roxy]

C'mon! Giving an answer like that is like starting the Dance of the Seven Veils and stopping at Veil #1.

Please to explain how honourable code work.

OME

Be careful what you ask for! You might get it.... I pulled Marlin_main.cpp into Vi (my favorite editor) and started searching. All of the G and M commands are implemented via switch statements with various case: lables. I searched for 906: It wasn't in there. But pretty much (there are exceptions) the case values are in ascending order. I got up into the 900's and this what is there:

    case 907: // M907 Set digital trimpot motor current using axis codes.
    {
      #if defined(DIGIPOTSS_PIN) && DIGIPOTSS_PIN > -1
        for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) digipot_current(i,code_value());
        if(code_seen('B')) digipot_current(4,code_value());
        if(code_seen('S')) for(int i=0;i<=4;i++) digipot_current(i,code_value());
      #endif
      #ifdef MOTOR_CURRENT_PWM_XY_PIN
        if(code_seen('X')) digipot_current(0, code_value());
      #endif
      #ifdef MOTOR_CURRENT_PWM_Z_PIN
        if(code_seen('Z')) digipot_current(1, code_value());
      #endif
      #ifdef MOTOR_CURRENT_PWM_E_PIN
        if(code_seen('E')) digipot_current(2, code_value());
      #endif
      #ifdef DIGIPOT_I2C
        // this one uses actual amps in floating point
        for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) digipot_i2c_set_current(i, code_value());
        // for each additional extruder (named B,C,D,E..., channels 4,5,6,7...)
        for(int i=NUM_AXIS;i<DIGIPOT_I2C_NUM_CHANNELS;i++) if(code_seen('B'+i-NUM_AXIS)) digipot_i2c_set_current(i, code_value());
      #endif
    }
    break;
    case 908: // M908 Control digital trimpot directly.
    {
      #if defined(DIGIPOTSS_PIN) && DIGIPOTSS_PIN > -1
        uint8_t channel,current;
        if(code_seen('P')) channel=code_value();
        if(code_seen('S')) current=code_value();
        digitalPotWrite(channel, current);
      #endif
    }
    break;

There is also some stuff to control the micro-stepping of the stepper motors:

    case 350: // M350 Set microstepping mode. Warning: Steps per unit remains unchanged. S code sets stepping mode for all drivers.
    {
      #if defined(X_MS1_PIN) && X_MS1_PIN > -1
        if(code_seen('S')) for(int i=0;i<=4;i++) microstep_mode(i,code_value());
        for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) microstep_mode(i,(uint8_t)code_value());
        if(code_seen('B')) microstep_mode(4,code_value());
        microstep_readings();
      #endif
    }
    break;
    case 351: // M351 Toggle MS1 MS2 pins directly, S# determines MS1 or MS2, X# sets the pin high/low.
    {
      #if defined(X_MS1_PIN) && X_MS1_PIN > -1
      if(code_seen('S')) switch((int)code_value())
      {
        case 1:
          for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) microstep_ms(i,code_value(),-1);
          if(code_seen('B')) microstep_ms(4,code_value(),-1);
          break;
        case 2:
          for(int i=0;i<NUM_AXIS;i++) if(code_seen(axis_codes[i])) microstep_ms(i,-1,code_value());
          if(code_seen('B')) microstep_ms(4,-1,code_value());
          break;
      }
      microstep_readings();
      #endif

There! We are to the Veil #2.

[old man emu]

Geez! I'm sorry I started this.
Angry emu.jpg (An angry emu)

It shows that to really fiddle about with these Gcodes, you have to be fluent in the programming language.

Got to admit, this old emu can't learn too many new tricks. Forget Veil #2. Just chuck a chaff bag over me and be done with it.


OME

[gmay3]

I bought one from the 3dmakerworld seller. Their picture doesn't show a Kysan sticker, but the motor came with one. Although I do have to chuckle - it looked like a label anyone could have printed and stuck on the motor.

Great! Thanks printbus, it looks like I'm going to be ordering a few of these. I was finally able to get the print I was having trouble with to complete successfully!

The solution was to set up a fan similar to how AbuMaia suggested. It kept the the motor much cooler in comparison to the extruder. Another thing I think helped was tightening the y belt down as tight as I could. I suspect the heating of the motor was the true culprit of this issue though!

Thank you all! OME I hope these suggestions are helpful for you!

[Drone]

Here is the ID tag for the MakerFarm Nema17 motor I got with my kit that stays very cool.



So if you want one from MakerFarm, and shipping is not an issue, this one is inexpensive from a reliable source.

[AbuMaia]

I'm currently printing out the 5th iteration of a redone Y-motor fan mount. I wanted to be able to mount the Y endstop switch on it too, save a T nut. Been tweaking and printing and mounting and tweaking all day.

[old man emu]

I think you blokes have missed something. You are concentrating on the temperature of the Y axis stepper. You forget that at the same time as the Y axis stepper was working flat out, the X axis one was working just as hard, and without error.

The other thing is, if the belt or pulley was loose, then subsequent layers would not be printed accurately on top of the preceding oout of position one.

Old Man Emu

[AbuMaia]

The X stepper was also out in open air on three sides, while the Y stepper was in a little box.

[printbus]

My guess is that the Y motor also has more work to do. Anyone know how the weight of the Y bed, heater, glass, and rolling hardware compares to the X-carriage and extruder parts? Plus, as the print grows, the weight that the Y-motor needs to move around keeps going up...