The New Hotness

Bird Feeder Tray Mount

The mixed flock attending the bird feeder in the back yard scatters enough seeds to attract the deer, so I added a tray underneath to catch the overspray:

Well, two trays, because it took a couple of iterations to make the solid model match reality:

Bird Feeder Tray Mount - show layout — Bird Feeder Tray Mount – show layout

The n-1 iteration was Close Enough™ and two trays are obviously better than one.

The “trays” are stray lids from the six gallon buckets we use for many purposes, including root-cellaring the vegetable garden harvest. The lid’s solid model was straightforward:

Bird Feeder Tray Mount - lid model — Bird Feeder Tray Mount – lid model

Removing the lid from a solid block produces the most complex part of the mount:

Bird Feeder Tray Mount - mount layout — Bird Feeder Tray Mount – mount layout

An aluminum plate on the outside (the gray slab in the overall view above) distributes the strain from the two M6 screws across the block.

A smaller block on the inside of the lid has a pair of square nuts:

Bird Feeder Tray Mount - segment layout — Bird Feeder Tray Mount – segment layout

All three parts build from their flattest side:

Bird Feeder Tray Mount - build layout — Bird Feeder Tray Mount – build layout

The downward facing clamp arch in the main block didn’t need support, but the square nut sockets in the segment definitely came out better with little support blocks inside; PrusaSlicer does a good job with most support structures.

The n-1 iteration used M6 rivnuts that were slightly too long after making the lid model match reality, so I switched to square nuts. The OpenSCAD code calculates the segment block length to match the actual screws, but 75 mm M6 screws and square nuts are barely long enough.

I clamped the outer block to the lid as a drill guide for the first hole, then pinned the block with a screw to ensure it didn’t slip while drilling the second hole:

Bird Feeder Tray Mount - drilling setup — Bird Feeder Tray Mount – drilling setup

Those were freehanded in the drill press at low speed with serious concentration; some things you just gotta do that way.

The mixed flock overwhelmingly approves the trays, to the extent a dozen birds clamor to use them: definitely a crowd-pleaser!

I’m certain you can buy pole-mounted trays, but what’s the fun in that?

The OpenSCAD source code as a GitHub Gist:

	// Bird feeder tray mount
	// Ed Nisley – KE4ZNU
	// 2025-11-06

	include <BOSL2/std.scad>

	Layout = "Show"; // [Build,Show,Lid,Mount,Segment,Nut]

	/* [Hidden] */

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

	HoleWindage = [0.2,0.2,0.2];
	Protrusion = 0.1;

	NumRibs = 12; // stiffening ribs
	NumSides = 8*NumRibs;

	$fn=NumSides;

	Gap = 5.0;

	WallThick = 9.0; // robust walls
	Kerf = 1.0; // clamp cut
	TapeThick = 0.5; // wrap around pole

	LidOD = 12; // main diameter in inches

	PoleOD = 1*INCH;

	PlateThick = 2.0; // backing plate for clamp

	Screw = [6.0,12.0,6.0]; // thread OD, washerOD, head
	ScrewLength = 75.0;

	ScrewOC = 60.0; // chosen to clear stiffening ribs in lid

	LidLayers = [ // bottom to top, ID = 0 means solid disk, LENGTH = exterior measurement
	[0,(LidOD-2(3/8))INCH,Protrusion], // 0 – below zero to prevent Z fighting
	[0,(LidOD-2(3/8))INCH,(3/8)*INCH], // 1 – base inside bucket
	[0,(LidOD+2(1/8))INCH,(1/8)*INCH], // 2 – flange
	[(LidOD-2(1/2))INCH,LidODINCH,(7/8)INCH], // 3 – sealing ring
	];

	LidOAH = LidLayers[1][LENGTH] + LidLayers[2][LENGTH] + LidLayers[3][LENGTH];
	LidTopDepth = (3/4)*INCH; // from highest part of interior

	MountBlockWidth = ScrewOC + 2*WallThick;

	BaseSagitta = LidLayers[1][OD]/2 – sqrt((LidLayers[1][OD]/2)^2 – (MountBlockWidth^2)/4);
	echo(BaseSagitta=BaseSagitta);

	PoleOffset = BaseSagitta + ((LidLayers[2][OD] – LidLayers[1][OD])/2) + WallThick + PoleOD/2;

	MountBlock = [PoleOffset + PoleOD/2 + WallThick – PlateThick,MountBlockWidth,LidOAH];
	echo(MountBlock=MountBlock);

	SegBlockOffset = ScrewLength – MountBlock.x – PlateThick; // assumes recessed
	SegmentBlock = [2*SegBlockOffset,MountBlock.y,LidTopDepth];

	Rib = [2*6.0,5.0,LidTopDepth]; // lid stiffening ribs
	RibAlign = 0 * 180/NumRibs; // position ribs wrt mount

	EdgeRadius = 3.0;

	//—–
	// Rivnut
	// The model collects all the magic numbers right here

	/*
	RivnutOAL = 15.0;

	module Rivnut() {

	union() {
	cyl(1.6,d=13.0,circum=true,anchor=BOTTOM);
	cyl(RivnutOAL,d=9.0,circum=true,anchor=BOTTOM);
	}

	}

	*/

	//—–
	// Square nut
	// The model collects all the magic numbers right here

	NutOAL = 5.0;

	module SquareNut() {

	cuboid([10.0,10.0,5.0],anchor=BOTTOM);

	}
	//—–
	// Bucket lid
	// Centered at XY=0, Z=0 at top of exterior flange

	module BucketLid(Interior=true,Expand=false) {

	render()
	union() {
	down(LidLayers[2][LENGTH])
	cyl(LidLayers[1][LENGTH],d=LidLayers[1][OD],anchor=TOP);
	cyl(LidLayers[2][LENGTH],d=LidLayers[2][OD],anchor=TOP);
	if (Interior) {
	if (false)
	down(Expand ? Protrusion : 0)
	tube(LidLayers[3][LENGTH] + (Expand ? 2*Protrusion : 0),
	id=LidLayers[3][ID],od=(Expand ? 2 : 1)*LidLayers[3][OD],anchor=BOTTOM);
	else
	difference() {
	cyl(LidLayers[3][LENGTH] + (Expand ? 2*Protrusion : 0),
	d=(Expand ? 2 : 1)*LidLayers[3][OD],anchor=BOTTOM);
	up(LidLayers[3][LENGTH] – LidTopDepth)
	cyl(LidTopDepth + (Expand ? 2*Protrusion : 0),
	d=LidLayers[3][ID],anchor=BOTTOM);
	}
	up(LidLayers[3][LENGTH] – LidTopDepth)
	for (i=[0:(NumRibs – 1)])
	zrot(i*360/NumRibs + RibAlign)
	right(LidLayers[3][ID]/2)
	cuboid(Rib,anchor=BOTTOM,rounding=1,edges="Z");
	}
	else
	down(Expand ? Protrusion : 0)
	cyl(LidLayers[3][LENGTH] + (Expand ? 2*Protrusion : 0),
	d=(Expand ? 2 : 1)*LidLayers[3][OD],anchor=BOTTOM);
	}
	}

	// Mount clamp

	module Mount() {
	render()
	difference() {
	cuboid(MountBlock,anchor=BOTTOM+LEFT,rounding=EdgeRadius,edges="X");
	left(LidLayers[1][OD]/2 – BaseSagitta)
	up(LidLayers[1][LENGTH] + LidLayers[2][LENGTH])
	BucketLid(Interior=false);
	right(PoleOffset) {
	cyl(3MountBlock.z,d=(PoleOD + HoleWindage.x + 2TapeThick),circum=true,anchor=CENTER);
	cuboid([Kerf,2MountBlock.y,3MountBlock.z]);
	}
	if (false)
	right(MountBlock.x – PlateThick)
	cuboid(3*[PlateThick,MountBlock.y,MountBlock.z],anchor=LEFT);
	up(LidOAH – LidLayers[3][LENGTH]/2)
	for (j=[-1,1])
	fwd(j*ScrewOC/2) {
	cyl(ScrewLength,d=Screw[ID] + HoleWindage.x,circum=true,orient=RIGHT,anchor=BOTTOM,$fn=6,spin=180/6);
	if (false)
	right(MountBlock.x + Protrusion)
	cyl(Screw[LENGTH] + Protrusion,d=Screw[OD] + HoleWindage.x,circum=true,
	orient=LEFT,anchor=BOTTOM,$fn=12,spin=180/12);
	}
	}
	}

	// Nut block segment inside lid

	module NutSegment() {

	render()
	difference() {
	cuboid(SegmentBlock,anchor=BOTTOM,rounding=EdgeRadius,edges="X");
	down(LidLayers[3][LENGTH] – LidTopDepth)
	left(LidLayers[1][OD]/2 – BaseSagitta)
	BucketLid(Interior=true,Expand=true);
	up(LidTopDepth – LidLayers[3][LENGTH]/2)
	for (j=[-1,1])
	fwd(j*ScrewOC/2) {
	left(SegmentBlock.x/2)
	cyl(ScrewLength,d=Screw[ID],circum=true,anchor=BOTTOM,$fn=6,spin=180/6,orient=RIGHT);
	left(SegmentBlock.x/2)
	yrot(90)
	SquareNut();
	}
	}

	}

	//—–
	// Build things

	if (Layout == "Lid")
	BucketLid();

	if (Layout == "Mount")
	Mount();

	if (Layout == "Segment")
	NutSegment();

	if (Layout == "Nut")
	Rivnut();

	if (Layout == "Show") {
	down(LidLayers[1][LENGTH] + LidLayers[2][LENGTH]) {
	Mount();
	color("Orange",0.5)
	up(LidOAH – LidLayers[3][LENGTH]/2)
	right(MountBlock.x + PlateThick)
	for (j=[-1,1])
	fwd(j*ScrewOC/2)
	cyl(ScrewLength,d=Screw[ID],circum=true,orient=LEFT,anchor=BOTTOM);
	}
	up(LidLayers[3][LENGTH] – LidTopDepth)
	NutSegment();

	color("Gray",0.4)
	right(PoleOffset)
	cylinder(3*MountBlock.z,d=(PoleOD),anchor=CENTER);
	color("Gray",0.4)
	left(LidLayers[1][OD]/2 – BaseSagitta)
	BucketLid();
	color("White",0.7)
	down(LidLayers[1][LENGTH] + LidLayers[2][LENGTH])
	right(MountBlock.x + 2*PlateThick)
	difference() {
	cuboid([PlateThick,MountBlock.y,MountBlock.z],anchor=BOTTOM+LEFT,rounding=EdgeRadius,edges="X");
	up(LidOAH – LidLayers[3][LENGTH]/2)
	for (j=[-1,1])
	fwd(j*ScrewOC/2)
	cyl(ScrewLength,d=Screw[ID],circum=true,orient=RIGHT,anchor=CENTER);
	}
	}

	if (Layout == "Build") {
	render()
	union() {
	difference() {
	left(MountBlock.z + Gap/2)
	up(PoleOffset – Kerf/2)
	yrot(90)
	Mount();
	cuboid([3MountBlock.z,2MountBlock.y,3*MountBlock.x],anchor=TOP);
	}
	render()
	right(Gap/2)
	intersection() {
	up(MountBlock.x)
	yrot(90)
	Mount();
	up(MountBlock.x – PoleOffset)
	right(MountBlock.z/2)
	cuboid([2MountBlock.z,2MountBlock.y,MountBlock.x],anchor=TOP);
	}
	right(2*MountBlock.z – BaseSagitta)
	up(SegmentBlock.x/2)
	yrot(-90)
	NutSegment();
	}
	}

view raw Bird Feeder Tray Mount.scad hosted with ❤ by GitHub

2025-11-19