The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Day: October 9, 2018

  • MPCNC: Modified Drag Knife Adapter Spring Constant

    The bars on the original MPCNC drag knife / plotter pen adapter had a 100 g/mm spring constant:

    MPCNC - Plotter pen force test
    MPCNC – Plotter pen force test

    Making the bars slightly thicker improved their print-ability:

    MPCNC knife adapter mods - OpenSCAD model
    MPCNC knife adapter mods – OpenSCAD model

    The reddish tint marks the new bars, with their location carefully tweaked to be coincident with the stock STL.

    Shoving the pen into the scale with 0.1 mm steps produces another unnervingly linear plot:

    Modified MPCNC pen adapter - Spring Constant data
    Modified MPCNC pen adapter – Spring Constant data

    Real plotter pens want about 20 g of force, so this isn’t the holder you’re looking for.

    A bunch of plots at Z=-1.0 mm turned out well with the ballpoint pen insert, though:

    MPCNC Modifed pen adapter - first plots
    MPCNC Modifed pen adapter – first plots

    The globs apparently come from plotting too fast for conditions; reducing the speed to 1500 mm/min works better.