Going bigger #2 – Testing mid span supports

New Home Forum don’t use this one need to sort -Assembly – MPCNC Going bigger #2 – Testing mid span supports

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  • #15581
    Profile photo of Matthew Kennedy
    Matthew Kennedy
    Participant

    Everything has been encouraging! Got the machine square, secured and the corners at uniform height. I took some pics (From the same elevation, etc for consistency) of the long center gantry span with and without supports, both under load (dewalt 660) and unloaded.

    There does appear to be some droop, but the actual presence of the router and heavy center didn’t seem to increase it.

    #15585
    Profile photo of Matthew Kennedy
    Matthew Kennedy
    Participant

    Again, my build is 2′ by 6′ usable area, using 23.5mm conduit, all in Petg.
    This series shows the measurements with two supports on the span near me, one in the center on the back span.

    Be advised, the mid-span supports here are a little too wide for the rollers to pass if you have the bolt heads down, much too wide if you have your lock nuts down. I notched a shallow strip a little way down to clear the heads, pictured. Be advised that you might want to modify those files if you use the top_support.stl file.

    So, results show that the unloaded center gantry piece came up 1 mm, just 1 mm short of the same pipe at the roller. Much more impressive is how much it comes up when under ‘load’! As the center/Z assembly approaches the center of the conduit, the supported outer spans pull the long gantry piece up, perhaps even a hair too high in my case. The effect is visible to the naked eye, and I believe it is due to the short Y-direction length giving that part of the gantry the rigidity to pull the long span up. A little tuning and two supports for each long span, and I bet it’ll be just fine.

    Of course, it has a dang lot to do with the masterful design of the new center block! I just enjoyed holding it and turning it in my hands for a while..

    Ack! I need to learn to hold my phone consistently!

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