It is mid-day Saturday and the Midwest RepRap Festival is in full swing. Saying that there is a lot of 3D printers here is an extreme understatement. There must be at least 100. Out of all these, there are a couple that stand out from the rest due to their non-standard geometry. These are both creations of [Nicholas Seward], called the Wally and Simpson.

Both of these printers were designed to not use linear rails or bearings and be as reprap-able as possible. For example, the Simpson’s only non-printed custom parts are the two wooden base plates and the print bed. The rest of the parts are general hardware and standard 3D printer electronics.


[Nicholas] is showing off something new this weekend (less than 2 weeks new, actually). It is a new printer, currently code named CoreXZ. Unlike his previous designs, the CoreXZ does use linear rails and bearings. The frame is laser cut and is held together with zip ties. This new design uses an h-bot style setup for movements in the X and Z axes. The Y axis is a standard moving bed design with linear rails and bearings.

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All axes are cord driven. Notice the cord pulleys, they are composed of two skate bearings. The radiused edges of the bearings provide a perfect groove for the cord to ride in. Like on the Wally and Simpson, the drive cords are tightened using guitar tuners and wrapped around drums that are powered by stepper motors.

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[Nicholas] is still tweaking the design and plans to release the source files to the community soon via his GitHub page. We are looking forward to seeing more of this printer in the future.

11 thoughts on “MRRF: CoreXZ

  1. I was there today and saw both the simpson and wally. I CANT WAIT!!!

    Kudos to hackaday, it was a great event! See you next year!

  2. Ahem, when it’s called “CoreXZ” it probably implies Core XY (, but flipped so it applies to XZ axis. Thus this is explicitly not an H-bot. Pretty please, can we get more pictures and video of this?

  3. I went there also. I’m glad that you covered the the event, I just wish someone manned your half of the table. I stopped by often while I was there (I live 3 hours away and couldn’t stay the while time). I really wanted a HaD T-Shirt, but couldn’t find anyone manning the station. Guess there is always next year right?

  4. I saw the CoreXZ machine, but it didn’t occur to me what was going on. I wish I had thought to ask. I wish I could have seen the parts it makes.

    1. Incidentally, isn’t the “CoreXZ” by someone else? The GitHub link doesn’t show any parts for that, and that machine was waaay down the aisle from the Simpson and Wally display.

      1. I just got back from the MRRF, and the “CoreXZ” discussed here is absolutely Nicholas Sewards design. It was so far down because he’s made so many printer designs and he brought them all with him! :)

        1. OK. I don’t remember any signage and I didn’t see anyone attending to it, nor was it running when I saw it.

          I did notice it was unusual, I just didn’t know what it was, or the motivation for the design. I imagine using the cords should eliminate the problem of wobble induced by the Z screws.

          1. I just brought the one computer so I alternated running my different printers.

            It does eliminate the wobble problem.

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