I am making a DIY 3D printer based on the Prusa MINI. I want to ask what smooth rod size is great for a printer with a 20x20x20 cm print volume. I am planning on using a 8 mm rod for the z-axis and 6 mm rods for the Y and X axis. I chose this as I am using a 2.5 kg.cm stepper motor for all the axis, so the X-axis needed to be light and the z-axis needed to be stronger and I chose 6 mm for the Y-axis as it is cheaper then other widths. I am worried if 6 mm is too thin to hold the hot-end (Which is a Bowden type) on the X-axis and a 20x20 cm glass plate on the Y-axis.

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    $\begingroup$ Are you on a budget? Linear rails would be very interesting for such a printer, it is not "strength" you should worry about, but "stiffness"! If you want to copy the Prusa model, copy it, not make changes, if thinner rods where giving the same performance, the manufacturer already would have switched to that. Note that the Prusa MINI is completely open source. $\endgroup$
    – 0scar
    Jan 9 at 13:26
  • $\begingroup$ Thanks ❤️😀, Yes I am on the budget, and I had already checked the price of those, and they are more expensive that the whole 3D printer. I just checked the prusa documentation, and it uses 10mm for the z-axis and 8mm for the Y and X axis. I might do as you said, but I am worried if the 2.5kg.cm stepper motors I am using can handle the weight of two 8mm rods and the prusa uses a 5kg.cm steppers. I am not really copying the prusa, I am just basing it on the axis design $\endgroup$
    – Leo Red
    Jan 9 at 14:39
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    $\begingroup$ Linear rails or at least Open-V-Slot are much stiffer than any rod can be. Note that a full TronXY X1 set comes down to about 150 €, but lacks a heated bed. $\endgroup$
    – Trish
    Jan 9 at 19:16
  • $\begingroup$ Thanks @Trish ❤️, I kept open-v slots away as they need more parts and need to be more accurate in the placement than rods, and might cost more. $\endgroup$
    – Leo Red
    Jan 10 at 4:05

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