Time to rebuild my large Kossel

It’s more than a year and a half since I published my large Kossel build blog entry.Since then I have upgraded it many times. Several people have built 3D printers based on this design, and some have asked for a more complete bill of materials. So I decided to create a page on this printer as it is now, including yet more upgrades.

If you’ve built my original 2020 Kossel variant and upgraded it, them you are already using the most advanced 3D printer electronics available – the Duet WiFi. So my focus this time is on upgrading the mechanics, so as to get the best out of the electronics. The new upgrades are:

  • 2017-03-22-20-17-04.jpg2040 extrusion for towers and top horizontals instead of 2020, for increased rigidity
  • Linear rails instead of wheeled carriages, for better alignment
  • Magnetic joints
  • Toothed idler pulleys, to reduce belt vibration
  • PCB effector with built-in lighting and nozzle contact probe, and matching PCB carriage adapters to ensure uniform rod spacing
  • E3D Titan extruder

This is not intended to be a budget printer. If you are in the UK, you can expect the parts to cost about £700 including VAT.

I considered moving the tower motors and electronics to the top, so that the electronics are more accessible instead of being under the bed, and better separated from the mains wiring. However, if the Robotdigg metal corners are used then the base would be only 40mm high, which is not enough to accommodate the power supply and the mains inlet components. One possible way round this would be to bolt three 2060 horizontal extrusions to the corners even though they are intended for 2040, and to mill an opening in one of the 2060 extrusions to accommodate the mains inlet components.

You can find the full instructions and the link to the parts list here.

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12 Responses to Time to rebuild my large Kossel

  1. Jan Fervers says:

    Thanks for this update… Regards Jan

  2. Damian Fernandez says:

    Comparing to carriages do you see a difference in quality using linear rails? where do you get 480mm magnetic rods?

  3. CEP says:


    Can’t wait to see additional pictures of this new updated version 🙂 . I’m currently following your path and intend to move to a Duet and a larger frame. But I’ve got 2 questions which didn’t find answers in your post :
    -#1 why did you change horizontal extrusion from 355mm to 390mm ?
    -#2 your ratio Rod/HorizontalExtrution changed in this configuration, from 355mm extrusion with 350mm rod eye-to-eye (~98%) to 390mm extrusion with 360mm rod ballCenter-to-ballCenter (~92%), why ? It doesn’t seem to be due a big change of offset ( from metal effector to PCB effector and from pulley system to linear carriage).

    Sorry if its a bit “technical for noob” but I’m still struggling with the dimensions of my future project :). Your choices are not random so there must be a good reason behind these 2 changes.

    thanks in advance for your answers.

    • davidcrocker says:

      It’s because the 2040 corners push the motors further in towards the centre of the printer than the 2020 ones did. So you need longer extrusions to get the belts at the same distance from the centre. I didn’t realise this until I started rebuilding it, so I am actually using 355mm extrusions with 17mm printed spacers at each end.

      I increased the rod length slightly to reduce the maximum joint angles needed, after my experience of hitting the limits of the Igus joints. But with the magnetic arms, I probably needn’t have bothered.

  4. gregchodaczek@gmail.com says:

    First off, thanks for all of your great work and advice.
    Second, why did you choose 16 tooth pulleys instead of 20 tooth?

  5. Joseph Tarling says:

    Hi David,
    I really like your Delta. I was going to build a corexy C-bot but after seeing your posts i’m now interested in build your clean looking printer. I saw in the bom that you have 2020 extrusion but in your updates you replaced it. Is the bom up to date? Thank you very much for spending your time to document this awesome build.

    • davidcrocker says:

      There is a link to the current BOM in https://miscsolutions.wordpress.com/dc42s-large-kossel-build/. I hope to post more photos of the assembly steps next month.

      • Joseph Tarling says:

        Awesome! That’ll be a great help.
        I was actually referring to that excel sheet. If that’s up to date with all the newest mods because I saw 2020 in there and I wasn’t sure if that’s a mistake or not. I should have looked at the steps to find out. Unfortunately it was really late last night when I pondered that question lol. If I only read the steps it’s right there in the base framing. Doh! Thanks again David for responding so quickly. I’m looking forward to seeing more photos of the assembly. 🙂

  6. Joseph Tarling says:

    Hi David,

    I’ve got another question for you… Have you looked into the flex2drive extruder or a “flying extruder with counterweight” setup?


    I’ll leaning towards the flex2drive setup for dual extrusion… Which one would you think would be best for this printer?

  7. davidcrocker says:

    I haven’t tried either, so I can’t comment.

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