Smoothie Aq CEVO

Traditionally, all movement is supported and constrained by bearings running on linear shafts. While alternatives are getting more common, this is also what I am going for on my CEVO. In this post I will compare a few different shafts. Traditionally most 3D printers have used solid stainless steel shafts. They are available cheaply from China in quite good, but sometimes varying, quality. The major disadvantage of these steel shaft is that they are quite heavy, but they are also quite stiff and smooth. Quality suppliers like Igus and Misumi have alternatives in aluminium and as tubes instead of solid, but these tends to be quite expensive. In later years quite cheap Carbon tubes have been available from China. Here and there people are experimenting with using these carbon tubes as an alternative to stainless steel shafts. They should be 3K roll wrapped carbon tubes. Their main advantage is that they are a lot lighter, and personally I think they also just look a lot cooler - for...

The aluminium bed will expand when heated, and I will have to take that into account when designing the mount for my bed. But how much does it expand? I googled a number of thermal expansion calculators, and somewhat to my surprise they don’t give the same result, although they do give results in the same ballpark. The calculator https://www.omnicalculator.com/physics/thermal-expansion seems well done and well documented. Using that, I get that a 300x300mm plate will expand 0.4mm in width when the temperature rises from 22 degree C to 80 degree C. The change in thickness is so small that it will not matter. Another issue is that the bed may warp. Obviously a thinner bed will warp more easily, and as I understand it, a rolled aluminum sheet will warp more than a cast sheet. The very best is therefor a thick cast aluminum sheet. I will have to take this into account when designing my bed mount. However, it also makes me think that it might not be so good an idea to print first lay...

The HEVO uses lead screws and steel rods for Z-movement and steel rods and belts for X- and Y-movement. A lot of experimentation are going on of using flat linear rails with bearing blocks and also some on using V-slots and wheels. This in some ways seems the way to go, but it does not (yet) seem clear to me which parts to choose in that direction, and I will stick with screws, rods and belts for the first iteration of my CEVO printer. I will however look into using carbon tubes instead of steel rods, and will also try a somewhat different configuration of both Z and X/Y.

Most CoreXY have a square outer frame, and I am using the HEVO design. I am using the 300x300x300 design from the configurator  but with an extra height of 100mm, so I can keep the electronics at the bottom. My plan is to use a thick MDF plate at the bottom, both for mounting the electronics and for adding weight and rigidity to the frame. Also, I will lower the top front bar, just to get a different look (an idea I got from somewhere I forgot). The precise measures of the 3030 extrusions are made to fit a 300x300mm build plate with the standard mounting parts. I will probably not use the standard parts, but will just choose or design parts so the fit with the standard frame and build plate. This fixes at least some variables, and allowed me to get an (almost) standard frame kit. more info will come here as I start the actual build...