Jump to content
Ultimaker Community of 3D Printing Experts
Sign in to follow this  

Ultimaker Original (1) - EXTRUDER POSITION

Recommended Posts

Hi guys,

I know that the limit switches can check if the extruder has reached the limit of the axis (X or Y). What I do not understand is how do the stepper drivers check the positioning of the extruder at any given moment, in order to understand how much it needs to move in each direction. Are there any other sensors that check the position of the extruder?



Share this post

Link to post
Share on other sites

There is no feedback. Generally you will use motors that are stronger than you need so that you can assume that when you tell the motor to move Xmm it will move Xmm. So after the firmware has established the home position it just assumes that the physical position of the head matches the "digital" position so to speak.


Share this post

Link to post
Share on other sites

From the firmware source -

#define DEFAULT_AXIS_STEPS_PER_UNIT {78.7402,78.7402,200.0*8/3,760*1.1} // default steps per unit for Ultimaker

These values represent the X, Y, Z and extruder stepper motor steps per mm.

So if the gcode calls for the head to move in the X direction 100mm, the firmware will issue 7874 steps. If the gcode then has the head move back 50mm in teh X direction, the firmware assumes it is starting at 100mm and so steps in the reverse direction 3937 steps.

This works as long as what IRobertI mentioned is true. The steppers must be strong enough so that steps occur when requested. If the steppers "miss a step", the print will be off as there is no feedback that the miss has occurred.


Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  


  • Our picks

    • Architect Design Contest | Vehicles.
      We're open for entries! - Design and submit your 3D designs of architectural entourage - vehicles - for a chance to win a large filament pack. Presenting an idea, an architectural design or something as big as an urban project isn't easy. A scaled model can really help to get your idea across.
        • Like
      • 14 replies
    • What The DfAM?
      I'm Steve Cox, an experienced engineer familiar with 3D printing. I wanted to share some DfAM guidelines with this community to help and make stronger parts.
      I'm also an Autodesk Certified Instructor for Fusion 360, so many of the images in ...
        • Thanks
        • Like
      • 18 replies

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!