Design choices of the MK3 and MK4
Hello,
Both the MK3 and MK4 series have a power screw and a rod with bearing on each side. The two power screws move the extruder up and down. Why a rod on each side is needed? Why not both sides have two rods with a power screw in between like the Mini+?
RE: Design choices of the MK3 and MK4
This design used in the MK3 and MK4 is designed for mechanical stability. The cart with the extruder is much heavier than the Mini and at the same time has a much larger lift in the horizontal direction. And how much would you like to change it?
RE: Design choices of the MK3 and MK4
Since the left and right vertical power screws are connected (indirectly) together, the extruder should be moving vertically parallel to the frontal plane. Does it? Is having at least one rod still better than none?
RE: Design choices of the MK3 and MK4
You will probably be surprised, precisely in order to maintain the parallelism of the X-axis with the pad, there are two screws and guide rods on both sides. Can you calculate the bending moment at different distances from one vertical bar at different distances of X cart from the bar? And since this system would not be rigid enough, guides and movement screws are used on both sides. And the Mini has a bowden extruder, where there is only a light hot end on the carriage and the length of the arm is limited, precisely because of these moments.
RE: Design choices of the MK3 and MK4
Thank you. What "pad" are you talking about? So for rigidity, it is better to have at least one rod on each side which is sufficient for the extruder in the MK3 and MK4 series. However, if the load is heavier, then on each side, it is better to have two rods with a power screw in between?
RE: Design choices of the MK3 and MK4
No. The bar guides on the sides only maintain the geometry and two bars on each side is pointless. Vertical loads are taken over by the movement screws. And that pad is the surface on which you place the steel printing plates.