Troubleshooting Limit switch issues.

Troubleshooting Limit switch issues.

Fracktal 3d Printers come with 3 Limit switches.
X axis 
Y axis
Z axis

Whenever these switches fail the printer faces certain issues like not being able to move in certain direction or going and crashing at the edges.
Below we have listed out the indicators of limit switch failure and how to fix them.

1. Checking Limit Switches.
      1. Access the printer via octo print. 
      2. Bring the carriage and Bed to the center. If you cant control them using the onscreen buttons turn of the machine and manually push them. 
      3. Give M119 command in terminal.
      4.  You should get this output
            > M119
Reporting endstop status
x_min: open
y_min: open
z_min: open
            Here the open status indicated that the limit switches are not triggered. Since the carriage and bed are at center the limit switches are not pressed. So they are showing open. In case a limit switch is faulty it will show triggered even without getting pressed.
      5. If all limit switches are showing correct output do the next step. Incase they are showing wrong values note the limit switch and later in this article you will be told how to fix it.
      6. Home the XY carriage and Bed to Z home. With XY and Z at home position all limit switches should be triggered. 
      7. Give M119 command in terminal.
      8.  You should get this output if all switches are correct.
            > M119
Reporting endstop status
x_min: TRIGGERED
y_min: TRIGGERED
z_min: TRIGGERED

NOTE: Limit switches work on OPEN or CLOSE status. There are chances of the switch giving both False open and False close status. So you need to check the switch in both the statuses.

Troubleshooting: 

Note: The limit switches on Fracktal Printers are normally open types. There will be small voltage flowing through the switch. Whenever the switch is press the flow of current is stopped and it shows the Status as TRIGGERED. In case there's a loose contact or wiring issue, it will show as TRIGGERED because there is no current flow.

Once you identify the limit switch which is giving faulty reading there can be 2 possibilities.
1. Faulty Limit switch.
2. Connectivity. 

Limit switch can be tested by 2 methods. 
1. Using Multimeter.
To check the limit switch using multimeter 
set the multimeter in connectivity mode> connect to ends of limit switch wire to the multimeter probes> If the switch is fine it should give a beep. If the switch is spoilt it will not give beep.
Check without pressing the button. you should get a beep is switch is fine
If you get the beep, Press the limit switch and the beep should stop. If the beep does not stop when you press the limit switch, it means the switch is damaged.
Check while pressing the button. If the limit switch is fine you should not get beep when button is pressed

2. Trial and error (In case you do not have multimeter)
If you do not have multimeter replace the faulty limit switch with other limit switch in your machine. If X limit switch is damaged, remove the Y limit switch and plug it into X limit switch port. And check Octaprint and m119. If the output is fine, then limit switch is the issue. If the same issue repeats even after changing limit switch then wiring is the issue. You need to check the connectivity and decide which part in damaged.

If the limit switch is fine still the octoprint is showing wrong values you need to check connectivity. 
To check connectivity

How to Test for Continuity with a Digital Multimeter


Basics idea on using ammeter.
  1. Turn the dial to Continuity Test mode. It will likely share a spot on the dial with one or more functions, usually resistance (Ω). With the test probes separated, the multimeter’s display may show OL and Ω.
  2. If required, press the continuity button.
Steps for measuring continuity with a digital multimeter
  1. First insert the black test lead into the COM jack.
  2. Then insert the red lead into the VΩ jack. When finished, remove the leads in reverse order: red first, then black.
  3. With the circuit de-energized, connect the test leads across the component being tested. The position of the test leads is arbitrary. Note that the component may need to be isolated from other components in the circuit.
  4. The digital multimeter (DMM) beeps if a complete path (continuity) is detected. If the circuit is open (the switch is in the OFF position), the DMM will not beep.
  5. When finished, turn the multimeter OFF to preserve battery life.

Continuity testing overview

  • Continuity is the presence of a complete path for current flow. A circuit is complete when its switch is closed.
  • A digital multimeter’s Continuity Test mode can be used to test switches, fuses, electrical connections, conductors and other components. A good fuse, for example, should have continuity.
  • A DMM emits an audible response (a beep) when it detects a complete path.
  • The beep, an audible indicator, permits technicians to focus on testing procedures without looking at the multimeter display.

Fracktal printers have custom made PCB's and use FFC instead of normal wires to reduce the mess by having too many wires. To check connectivity issues you need to use a multimeter.

Note: Certain components follow closed loop circuit. Closed loop systems will show connectivity even though there is breakage in circuit. So if you are testing for continuity of the closed loop circuit make sure you remove the end component and make it a open loop (Ex: Remove Limit switch, hot end, thermistor etc incase you need their connectivity )

To check the continuity of the circuit there are test points on the PCB's.
Step1.
Check the component whose continuity you have to check. (Ex - Limit switch)
Step2. 
Find the test point for the component in the first board, consider Carriage board. (ex: X axis Limit switch has test point X-LIM)
Step 3. 
Find the test point in other board. consider Chassys board.  Keeping the two multimeter probes on the required test point should give you beeping sound if there is no problem with the continuity of the circuit. If there is breakage/Issue with the circuit the probe will not beep.
Ex: When you keep probe on X limit test point of carriage board and on X limit test point of chassys board it should beep if the connections are fine. If the connection has issue the multimeter will not beep.
4. Once issue is found with the connectivity you need to check the FFC for breakage or damage. 
5. If you are checking connectivity between 2 boards where there is a PCB in between you need to check connectivity between the individual boards to determine where the connection is faulty.
Ex: If you check connectivity between a point in carriage board and between MKS daughter board and find the connectivity to be faulty, you need to check connectivity between Carriage PCB and Chassys PCB. And then between Chassys PCB and Daughter board of MKS.

Note: If the connectivity is fine but still there is no power output at the connecting pin there are chances that the board is damaged. To confirm if the board is damaged you need to check connectivity between the test point and output pin like JST pin or FFC connector.
Checking connectivity between FFC connector pin. Normally these pins get burnt due to various reasons)
Checking JST pin terminal and test point. Sometimes due to loose connection or short circuit the connectors get burnt.

    • Related Articles

    • SMPS not turning ON

      SMPS may not turn because of these reasons. 1. SMPS is not getting power supply. 2. SMPS is spoilt 3. SMPS is detecting a short in machine circuit and is auto Shutting. Troubleshooting: Note: Checking SMPS input when machine is on is risky task. You ...
    • Error: Heating failed, system stopped! Heater_ID: Bed

      This error is show when the Bed does not reaches the required temperature as set by the machine. To confirm that the error is related to bed you can check the last word of the error which says "Bed".  Schematics of Heater wiring. This error comes ...
    • The printer does not turn on

      If your printer doesn't turn on, or it keeps turning off during preheating, the most common causes are either a wrong voltage on the PSU or a blown fuse. The printer does not turn on If your printer does not turn on at all, then there might be a more ...
    • Thermal Runway, System Stopped Error

      Fracktal printers come with inbuilt feature to avoid accidents by over heating of the nozzle or heater cartridge. Due to some issue with printer if the heater cartridge heats beyond certain temperature it can lead to melting of hot end and also fire ...
    • Changing SMPS- Extended.

      Fractal Printers are designed with serviceability in mind. Changing SMPS in Julia Extended can be done with the help of a + Screw driver and 2.5mm Allen key (Allen Key is provided with the Accessory box).  Steps to replace SMPS: 1. Switch off the ...
    • Popular Articles

    • SMPS not turning ON

      SMPS may not turn because of these reasons. 1. SMPS is not getting power supply. 2. SMPS is spoilt 3. SMPS is detecting a short in machine circuit and is auto Shutting. Troubleshooting: Note: Checking SMPS input when machine is on is risky task. You ...
    • Layer Shifting caused by pulley slipping down

      Motor Pulley is mounted on Motor shaft with the help of a grub screw. The pulley acts as a bridge for transferring the motors rotary motion to the belts. The motor pulley comes under high stresses and sometimes may get displaced. The displacement of ...
    • Troubleshooting Limit switch issues.

      Fracktal 3d Printers come with 3 Limit switches. X axis  Y axis Z axis Whenever these switches fail the printer faces certain issues like not being able to move in certain direction or going and crashing at the edges. Below we have listed out the ...
    • Pro Maintainance

      Maintainance
    • Buying a 3D printer.

      3D printing technology is broadly classified into FDM, SLA and SLS printing. We at Fracktal works Manufacture and sell machines related to FDM and SLA. If you need parts printed using SLS you can use our Fractory service. We have mentioned few of the ...
    • Recent Articles

    • Removing carriage board - Julia Extended.

      Carriage board is a small board mounted on the carriage. To remove the carriage board follow the steps below. Note: Remove filament before removing carriage cover. 1. Remove carriage cover. The carriage cover is fastened by 2 screws. Please be ...
    • Sending Gcode to Fracktal care for troubleshooting.

      Analysing the Gcode is one among the primary steps done while troubleshooting issues. The gcode which may be fine in your system may get corrupted while uploading to your printer. To make sure this corruption has not happened we recommend analysing ...
    • Material (filament) storage SOP

      3D printing filaments are hygroscopic in nature. PLA Nylon and PVA are extremly hygroscopic and storing them in air tight containers with dessicants is a must. Other filaments also need to be stored in air tight container but can be exposed to ...
    • SMPS not turning ON

      SMPS may not turn because of these reasons. 1. SMPS is not getting power supply. 2. SMPS is spoilt 3. SMPS is detecting a short in machine circuit and is auto Shutting. Troubleshooting: Note: Checking SMPS input when machine is on is risky task. You ...
    • Changing SMPS- Extended.

      Fractal Printers are designed with serviceability in mind. Changing SMPS in Julia Extended can be done with the help of a + Screw driver and 2.5mm Allen key (Allen Key is provided with the Accessory box).  Steps to replace SMPS: 1. Switch off the ...