The New Hotness

Rather than attach a spoil board directly to the bench top under the MPCNC, one can grab it in bar clamps anchored to the bench, which requires suitable mounts. Because bar clamps are all the same, one must be flipped over to point the other way, soooo the mounts come in mirror-image sets.

Holding the clamp on the left side of the table:

Bar Clamp Mounts - Left - solid model — Bar Clamp Mounts – Left – solid model

For the right-side clamp:

Bar Clamp Mounts - Right - solid model — Bar Clamp Mounts – Right – solid model

The chunky clamp prints on its end, with its bottom surface facing away from you, to let the block in the middle print without support. In that orientation, the bar slides in from the top.

The fancy rounded corners happened while I iterated on getting the dimensions right.

Actually printing and installing the things turned out to be separate challenges.

The OpenSCAD source code as a GitHub Gist:

	// MPCNC Bar Clamp Mounts
	// Ed Nisley KE4ZNU – 2018-02-03

	Layout = "Build"; // BarEnd EndBlock ScrewBlock Build

	Chirality = "Right"; // bar handedness = side with opening

	/* [Extrusion] */

	ThreadThick = 0.25; // [0.20, 0.25]
	ThreadWidth = 0.40; // [0.40]

	/* [Hidden] */

	Protrusion = 0.1; // [0.01, 0.1]

	HoleWindage = 0.2;

	function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

	ID = 0;
	OD = 1;
	LENGTH = 2;

	//- Adjust hole diameter to make the size come out right

	module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes
	Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
	FixDia = Dia / cos(180/Sides);
	cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides);
	}

	/* [Clamp] */

	BarEndOut = [34.5,21.0]; // outside dimensions
	BarEndIn = [28.0,18.0]; // … inside
	BarEndSlot = [2.8,11.5]; // slot on open side
	BarEndRadius = 1.5; // corner rounding
	NumSides = 3*4; // … and sides

	BarHeightOC = 22.0; // min height above bench

	Clearance = 0.2; // overall bar clearance

	PinOffset = [14.0,2.5]; // clamp hardware pin location
	PinOD = 6.5; // … pin OD

	WallThick = 5.0; // basic wall & floor thickness

	EndBlockSize = [2PinOffset.x + WallThick,BarEndOut.x + 2WallThick,BarHeightOC + BarEndOut.y/2];

	ScrewBlockSize = [2PinOffset.x,BarEndOut.x + 2WallThick,BarHeightOC + BarEndOut.y/2];


	//—–
	// Define shapes

	// Aluminum bar extrusion

	module BarEnd(Length = 2.0,Hollow=true) {

	linear_extrude(height=Length,convexity=3)
	offset(delta=Clearance)
	difference() {
	hull()
	for (i=[-1,1], j=[-1,1])
	translate([i(BarEndOut.x/2 – BarEndRadius),j(BarEndOut.y/2 – BarEndRadius)])
	circle(r=BarEndRadius,$fn=3*4); // not related to block corner rounding
	if (Hollow) {
	translate([BarEndOut.x/2 – BarEndIn.x/2 – BarEndSlot.x,0])
	square(BarEndIn,center=true);
	translate([BarEndOut.x/2,0])
	square([BarEndOut.x,BarEndSlot.y],center=true);
	}
	}
	}

	// Block supporting open end of Bar

	module EndBlock() {

	Normal = (Chirality == "Left") ? [0,0,0] : [0,1,0];
	Radius = WallThick;

	mirror(Normal)
	difference() {
	if (true)
	hull() {
	dx = EndBlockSize.x/2 – Radius;
	dy = EndBlockSize.y/2 – Radius;
	for (i=[-1,1],j=[-1,1])
	translate([idx,jdy,EndBlockSize.z – Radius]) {
	sphere(r=Radius,$fn=NumSides);
	cylinder(r=Radius,h=Protrusion,$fn=NumSides);
	}
	for (i=[-1,1],j=[-1,1])
	translate([idx,jdy,0])
	cylinder(r=Radius,h=Protrusion,$fn=NumSides);
	}
	else
	translate([-EndBlockSize.x/2,-EndBlockSize.y/2,0])
	cube(EndBlockSize,center=false);
	translate([EndBlockSize.x/2 – PinOffset.x,0*PinOffset.y,-Protrusion])
	rotate(180/8)
	PolyCyl(PinOD,2*EndBlockSize.z,8);
	translate([EndBlockSize.x/2 – 2*PinOffset.x,0,BarHeightOC])
	rotate([0,90,0]) rotate(-90)
	BarEnd(Length=EndBlockSize.x);
	}
	}

	// Block supporting screw end of Bar
	// Ad-hoc chamfers to clear screw mount castings

	module ScrewBlock() {

	Normal = (Chirality == "Left") ? [0,0,0] : [0,1,0];
	Radius = WallThick;

	mirror(Normal)
	difference() {
	if (true)
	hull() {
	dx = ScrewBlockSize.x/2 – Radius;
	dy = ScrewBlockSize.y/2 – Radius;
	for (i=[-1,1],j=[-1,1])
	translate([idx,jdy,ScrewBlockSize.z – Radius]) {
	sphere(r=Radius,$fn=NumSides);
	cylinder(r=Radius,h=Protrusion,$fn=NumSides);
	}
	for (i=[-1,1],j=[-1,1])
	translate([idx,jdy,0])
	cylinder(r=Radius,h=Protrusion,$fn=NumSides);
	}
	else
	translate([0,0,ScrewBlockSize.z/2])
	cube(ScrewBlockSize,center=true);
	translate([0,PinOffset.y,-Protrusion])
	rotate(180/8)
	PolyCyl(PinOD,2*ScrewBlockSize.z,8);
	translate([-ScrewBlockSize.x/2 – Protrusion,0,BarHeightOC])
	rotate([0,90,0]) rotate(-90)
	BarEnd(Length=ScrewBlockSize.x + 2*Protrusion,Hollow=false);
	for (i=[-1,1])
	translate([i*ScrewBlockSize.x/2,ScrewBlockSize.y/2,ScrewBlockSize.z – Protrusion])
	rotate(45)
	cube([sqrt(2)WallThick,sqrt(2)WallThick,2*ScrewBlockSize.z],center=true);
	}
	}


	//—–
	// Build things

	if (Layout == "BarEnd")
	BarEnd();

	if (Layout == "EndBlock")
	EndBlock();

	if (Layout == "ScrewBlock")
	ScrewBlock();

	if (Layout == "Build") {
	translate([EndBlockSize.z/2,0.6*EndBlockSize.y,EndBlockSize.x/2])
	rotate([0,-90,0])
	EndBlock();
	translate([0,-0.6*ScrewBlockSize.y,0])
	ScrewBlock();
	}

view raw Bar Clamp Mounts.scad hosted with ❤ by GitHub

The original doodles, with initial dimensions & some bad ideas:

Bar Clamp Mount - Dimension Doodles — Bar Clamp Mount – Dimension Doodles

The New Hotness

MPCNC: Bar Clamp Mounts