Direct Drive Upgrade

Improve the printhead drive system

The short drive belts are a complete nightmare, and should be relegated to the bin.
Just stick the steppers right on the end of the shafts! Here is how:

Here is a .pdf Assembly drawing to show what to do. Here is the Motor_Bracket_9 file for the motor bracket (updated version from in the photos).

This modification has the following benefits:

1) No short belts, so no need to constantly fight to keep them tensioned
2) Instead of each axis having 2 belts in series (compounded backlash error), you only have one. So backlash is much reduced.
3) Reduces motor noise a little by putting some material between the main case (which acts like a loud speaker) and the motor

If your belts are already perfectly set up and tuned, you wont notice a really big improvement with this upgrade. But it will stay
well set up much better, and if your system has a lot of slop in the short belts you will discover a big improvement in print layer to layer
repeatability (noticed most on large flat vertical walls).

Note that often the ground steel axial rods are cut by hydraulic guillotine. This tends to deform up to 10mm of both ends of the rod. So make
sure you cut off 15mm of BOTH ends..THEN trim it to length. Otherwise you may well find that one end wont fit through the bearings.

The tolerance I suggest is tighter than the standard bars, so you will need light oil and a “wiggle” each bar through the bearings. Dont expect
them to just slide through with no resistance.

4 Comments

  1. Installed this upgrade on the first day I received my Ultimaker. I had planned on designing the same type of setup, then I found your website and saw you had already done all the hard work. Excellent design and documentation! I’ve been using the printer nearly non-stop with great results. Thank you!

  2. Fantastic design, once I pluck up the courage (or more likely back lash drives me to it) I may give it a go. Just one question – is there a particular reason why the X motor is on the front? Could it not go diagonally opposite on the back?

    • You can put the motors of which-ever end of the shaft you like, I went for these positions because its just plug-and-play.

      To swap to the other end the stepper then must go in “reverse”, which you can achieve with either modifiying the cable, or messing with the firmware. Both possible, but both things I would rather use the time required to do something else….

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