new RAMBO stepper issues

i blew the 32U2 USB IC a few weeks ago on my RAMBO board and got a rma replacement the other day. however after flashing the stock AO-101 firmware im getting odd stepper problems. the axes are only traveling about halfway before stopping at their supposed firmware/software limits, also their tune doesn’t sound right.

im thinking perhaps there is some sort of stepping setting that im missing in the firmware that the latest RAMBO revision requires vs the older revision?

After homing, what is your range of travel? Would you mind posting your Configuration.h file?


actual travel is cut in half. i am using the stock firmware/config files from the current marlin download link in my first post.


// This configurtion file contains the basic settings.
// Advanced settings can be found in Configuration_adv.h
// BASIC SETTINGS: select your board type, temperature sensor type, axis scaling, and endstop configuration

//User specified version info of THIS file to display in [Pronterface, etc] terminal window during startup.
//Implementation of an idea by Prof Braino to inform user that any changes made
//to THIS file by the user have been successfully uploaded into firmware.
#define STRING_VERSION_CONFIG_H > “2012-11-26” > > //Personal revision number for changes to THIS file.
#define STRING_CONFIG_H_AUTHOR > “LulzBot” > > //Who made the changes.

// This determines the communication speed of the printer
//#define BAUDRATE 250000
#define BAUDRATE 115200

//// The following define selects which electronics board you have. Please choose the one that matches your setup
// Gen7 custom (Alfons3 Version) = 10 ">> "
// Gen7 v1.1, v1.2 = 11
// Gen7 v1.3 = 12
// Gen7 v1.4 = 13
// MEGA/RAMPS up to 1.2 = 3
// RAMPS 1.3 = 33 (Power outputs: Extruder, Bed, Fan)
// RAMPS 1.3 = 34 (Power outputs: Extruder0, Extruder1, Bed)
// Gen6 = 5
// Gen6 deluxe = 51
// Sanguinololu 1.2 and above = 62
// Melzi = 63
// Ultimaker = 7
// Teensylu = 8
// Gen3+ =9
// Rambo = 301

#define MOTHERBOARD 301

//=============================Thermal Settings ============================
//–NORMAL IS 4.7kohm PULLUP!-- 1kohm pullup can be used on hotend sensor, using correct resistor and table
//// Temperature sensor settings:
// -2 is thermocouple with MAX6675 (only for sensor 0)
// -1 is thermocouple with AD595
// 0 is not used
// 1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
// 2 is 200k thermistor - ATC Semitec 204GT-2 (4.7k pullup)
// 3 is mendel-parts thermistor (4.7k pullup)
// 4 is 10k thermistor !! do not use it for a hotend. It gives bad resolution at high temp. !!
// 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan) (4.7k pullup)
// 6 is 100k EPCOS - Not as accurate as table 1 (created using a fluke thermocouple) (4.7k pullup)
// 7 is 100k Honeywell thermistor 135-104LAG-J01 (4.7k pullup)
// 1k ohm pullup tables - This is not normal, you would have to have changed out your 4.7k for 1k
// (but gives greater accuracy and more stable PID)
// 51 is 100k thermistor - EPCOS (1k pullup)
// 52 is 200k thermistor - ATC Semitec 204GT-2 (1k pullup)
// 55 is 100k thermistor - ATC Semitec 104GT-2 (Used in ParCan) (1k pullup)

#define TEMP_SENSOR_0 7
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0

// Actual temperature must be close to target for this long before M109 returns success
#define TEMP_RESIDENCY_TIME 10 > // (seconds)
#define TEMP_HYSTERESIS 3 > // (degC) range of +/- temperatures considered “close” to the target one
#define TEMP_WINDOW 1 > // (degC) Window around target to start the recidency timer x degC early.

// The minimal temperature defines the temperature below which the heater will not be enabled It is used
// to check that the wiring to the thermistor is not broken.
// Otherwise this would lead to the heater being powered on all the time.
#define HEATER_0_MINTEMP 5
#define HEATER_1_MINTEMP 5
#define HEATER_2_MINTEMP 5
#define BED_MINTEMP 5

// When temperature exceeds max temp, your heater will be switched off.
// This feature exists to protect your hotend from overheating accidentally, but NOT from thermistor short/failure!
// You should use MINTEMP for thermistor short/failure protection.
#define HEATER_0_MAXTEMP 250
#define HEATER_1_MAXTEMP 250
#define HEATER_2_MAXTEMP 250
#define BED_MAXTEMP 150

// If your bed has low resistance e.g. .6 ohm and throws the fuse you can duty cycle it to reduce the
// average current. The value should be an integer and the heat bed will be turned on for 1 interval of

// PID settings:
// Comment the following line to disable PID and enable bang-bang.
#define PIDTEMP
#define PID_MAX 255 > // limits current to nozzle; 255=full current
#ifdef PIDTEMP

//#define PID_DEBUG // Sends debug data to the serial port.
//#define PID_OPENLOOP 1 // Puts PID in open loop. M104 sets the output power in %
#define PID_INTEGRAL_DRIVE_MAX 255 > //limit for the integral term
#define K1 0.95 > //smoothing factor withing the PID
#define PID_dT ((16.0 * 8.0)/(F_CPU / 64.0 / 256.0)) > //sampling period of the

// If you are using a preconfigured hotend then you can use one of the value sets by uncommenting it
// Ultimaker
#define DEFAULT_Kp 22.2
#define DEFAULT_Ki 1.08
#define DEFAULT_Kd 114

// Makergear
// #define DEFAULT_Kp 7.0
// #define DEFAULT_Ki 0.1
// #define DEFAULT_Kd 12

// Mendel Parts V9 on 12V
// #define DEFAULT_Kp 63.0
// #define DEFAULT_Ki 2.25
// #define DEFAULT_Kd 440
#endif > // PIDTEMP

//this prevents dangerous Extruder moves, i.e. if the temperature is under the limit
//can be software-disabled for whatever purposes by
//if PREVENT_DANGEROUS_EXTRUDE is on, you can still disable (uncomment) very long bits of extrusion separately.

#define EXTRUDE_MAXLENGTH (X_MAX_LENGTH+Y_MAX_LENGTH) > //prevent extrusion of very large distances.

//=============================Mechanical Settings===========================

// Uncomment the following line to enable CoreXY kinematics
// #define COREXY

// corse Endstop Settings
#define ENDSTOPPULLUPS > // Comment this out (using // at the start of the line) to disable the endstop pullup resistors


// fine Enstop settings: Individual Pullups. will be ignord if ENDSTOPPULLUPS is defined


// The pullups are needed if you directly connect a mechanical endswitch between the signal and ground pins.
const > bool X_ENDSTOPS_INVERTING = > true> ; > // set to true to invert the logic of the endstops.
const > bool Y_ENDSTOPS_INVERTING = > true> ; > // set to true to invert the logic of the endstops.
const > bool Z_ENDSTOPS_INVERTING = > true> ; > // set to true to invert the logic of the endstops.

// For Inverting Stepper Enable Pins (Active Low) use 0, Non Inverting (Active High) use 1
#define X_ENABLE_ON 0
#define Y_ENABLE_ON 0
#define Z_ENABLE_ON 0
#define E_ENABLE_ON 0 > // For all extruders

// Disables axis when it’s not being used.
#define DISABLE_X > false
#define DISABLE_Y > false
#define DISABLE_Z > false
#define DISABLE_E > false > > // For all extruders

#define INVERT_X_DIR > false > > // for Mendel set to false, for Orca set to true
#define INVERT_Y_DIR > true > > // for Mendel set to true, for Orca set to false
#define INVERT_Z_DIR > false > > // for Mendel set to false, for Orca set to true
#define INVERT_E0_DIR > true > > // for direct drive extruder v9 set to true, for geared extruder set to false
#define INVERT_E1_DIR > true > > // for direct drive extruder v9 set to true, for geared extruder set to false
#define INVERT_E2_DIR > true > > // for direct drive extruder v9 set to true, for geared extruder set to false

// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

#define min_software_endstops > true > > //If true, axis won’t move to coordinates less than HOME_POS.
#define max_software_endstops > true > > //If true, axis won’t move to coordinates greater than the defined lengths below.
// Travel limits after homing
#define X_MAX_POS 190
#define X_MIN_POS 0
#define Y_MAX_POS 200
#define Y_MIN_POS 0
#define Z_MAX_POS 100
#define Z_MIN_POS 0


// The position of the homing switches. Use MAX_LENGTH * -0.5 if the center should be 0, 0, 0
#define X_HOME_POS 0
#define Y_HOME_POS 0
#define Z_HOME_POS 0

#define NUM_AXIS 4 > // The axis order in all axis related arrays is X, Y, Z, E
#define HOMING_FEEDRATE {5060, 5060, 4*60, 0} > // set the homing speeds (mm/min)

// default settings

#define DEFAULT_AXIS_STEPS_PER_UNIT {50.25,50.25,756,408} > // default steps per unit for AO-101
#define DEFAULT_MAX_FEEDRATE {500, 500, 5, 45} > // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} > // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 3000 > // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 > // X, Y, Z and E max acceleration in mm/s^2 for r retracts

#define DEFAULT_XYJERK 20.0 > // (mm/sec)
#define DEFAULT_ZJERK 0.4 > // (mm/sec)
#define DEFAULT_EJERK 5.0 > // (mm/sec)

//=============================Additional Features===========================

// the microcontroller can store settings in the EEPROM, e.g. max velocity…
// M500 - stores paramters in EEPROM
// M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).
// M502 - reverts to the default “factory settings”. You still need to store them in EEPROM afterwards if you want to.
//define this to enable eeprom support
//to disable EEPROM Serial responses and decrease program space by ~1700 byte: comment this out:
// please keep turned on if you can.

//LCD and SD support
//#define ULTRA_LCD //general lcd support, also 16x2
#define SDSUPPORT > // Enable SD Card Support in Hardware Console

//#define ULTIMAKERCONTROLLER //as available from the ultimaker online store.
//#define ULTIPANEL //the ultipanel as on thingiverse

#ifdef ULTIMAKERCONTROLLER > //automatic expansion
#define NEWPANEL

// #define NEWPANEL //enable this if you have a click-encoder panel
#define ULTRA_LCD
#define LCD_WIDTH 20
#define LCD_HEIGHT 4

// Preheat Constants
#define PLA_PREHEAT_FAN_SPEED 255 > // Insert Value between 0 and 255

#define ABS_PREHEAT_FAN_SPEED 255 > // Insert Value between 0 and 255

#else > //no panel but just lcd
#ifdef ULTRA_LCD
#define LCD_WIDTH 16
#define LCD_HEIGHT 2

// Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
//#define FAST_PWM_FAN

// M240 Triggers a camera by emulating a Canon RC-1 Remote
// Data from: >
// #define PHOTOGRAPH_PIN 23

#include > “Configuration_adv.h”
#include > “thermistortables.h”

#endif > //__CONFIGURATION_H

In the Configuration.h file you posted, the travel limits look normal for the AO-101:

#define max_software_endstops true //If true, axis won't move to coordinates greater than the defined lengths below.
// Travel limits after homing
#define X_MAX_POS 190
#define X_MIN_POS 0
#define Y_MAX_POS 200
#define Y_MIN_POS 0
#define Z_MAX_POS 100
#define Z_MIN_POS 0

Which sets the build area(movement range) of 190mm x 200mm x 100mm. I would recommend homing all 3 axes and then sending the “M119” command in the Pronterface terminal window and see what the endstops report. Then move the other 3 axes until they stop moving and issue the same command again. Have you reflashed the firmware?

If your movement is cut exactly in half, I bet you replaced a 1.0 RAMBo with a 1.1. The 1.1 board uses 1/16th steps whereas the 1.0 uses 1/8.

Double your steps per mm and see if the problem goes away.


That’s exactly what we did to solve the issue! In Configuration_adv.h on lIne 247 you can also change the microstepping if desired.

thank you geneb for the reply! turns out this was this issue. i resolved it a long time ago but never got a chance to make sure my new steps were calibrated, which i am getting ready to do. i also went ahead and set the microsteps to 1/16th stepping on x,y,z,e.

orias, im using my calipers like we talked about. how accurate should things be?

when my z is set to 10mm, actual is 10mm, by time i get to set 50mm the actual is 50.94mm, what is acceptable divination for each axis?

I would move the Z axis 100-200mm and recalculate the steps per unit, several times to see if the results are consistent. If so, I would then reflash the firmware with the new steps per unit. If at 50mm of travel you’re almost off at 1mm, you may notice errors when printing larger objects.

i was able to calibrate the z steps at 90mm to 90mm, however as i move it down im getting the following results


ans so on