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.
While the rest of the Master Gardener tour group walked on to the Island, I lay face-down on the Channel Bridge at Innisfree for a frog’s eye perspective:
Painting these pastels would pose a challenge:
Hand-held with the Sony DSC-H5 on an overcast day that accentuated those colors.
A one-year-old magnesium rod looks pretty good, all things considered:
The previous one was still working after seven years, although I had to wreck it to get it out…
Based on tweaking the measurements from the nut trap block trial, this block attaches to the inner floor plate of the magazine and reduces the magazine’s capacity to 10 rounds:
The horn fits between the follower’s pegs, so that chopping the pegs off won’t increase the magazine’s capacity. Chopping the horn off without modifying the follower won’t make any difference, either. As nearly as I can tell, chopping the pegs off the follower will destabilize it enough that it’ll roll over atop the spring, but I admit to not actually trying that.
The yellow comb supports the overhang that captures the tab around the magazine spring and there’s a tiny support spider inside the lower nut clearance that holds the ceiling in place:
The inner nut trap probably droops a bit without any support, but there’s no way to tell when it’s printed as one solid piece. That trap will hold the blob of steel-filled epoxy that secures the screw and helps prevent the block from turning, so it’s not really a nut trap and doesn’t require a precision fit. The vent tube from the top of the screw shaft gives the air and any excess epoxy an exit path.
Here’s a bottom view of two blocks, showing the support structures and the results:
I poked the tips of a snap ring pliers into the spider and twisted it out. The comb snaps off with fingernail pressure.
You could also print it without support by laying it flat, then glue the halves together with alignment pins. This is a bottom view:
The OpenSCAD program has a handful of configuration settings that determine which of those blocks it produces, which components appear, and how it’s oriented.
Installed in a Browning magazine, the block looks like this:
A detail of the bottom shows the notch capturing the spring tab:
I think the top surface would benefit from a small bevel to ease the spring around the block, but that’s in the nature of fine tuning.
Not having heard back from my legislators yet, I still don’t know whether this counts as a readily reversible modification. I have my doubts, what with it being plastic and all, but we shall see.
The OpenSCAD source code:
// Browning Hi-Power Magazine Block
// Ed Nisley KE4ZNU December 2013
Layout = "Whole"; // Show Whole Split
// Show = section view for demo, not for building
// Whole = upright for steel or plastic
// Split = laid flat for plastic show-n-tell assembly
AlignPins = (Layout == "Split"); // pins only for plastic show-n-tell
Support = (Layout != "Split"); // no support for split
//- Extrusion parameters must match reality!
// Print with 2 shells and 3 solid layers
ThreadThick = 0.15;
ThreadWidth = 0.40;
HoleWindage = 0.2;
Protrusion = 0.1; // make holes end cleanly
//----------------------
// Dimensions
Angle = 12.5; // from vertical
SpringID = 10.3; // magazine spring curvature (measure with drill shank)
SpringRadius = SpringID / 2;
Length = 24.0; // front-to-back perpendicular to magazine shaft
Height = 18.0; // bottom-to-top, parallel to magazine shaft
// 18 = 10 round capacity
RectLength = Length - SpringID; // block length between end radii
HornBaseOD = 8.0; // fits between follower pegs to prevent shortening
HornTipOD = 5.0;
HornAddTip = (HornTipOD/2)*tan(Angle);
HornAddBase = (HornBaseOD/2)*tan(Angle);
HornAddLength = HornAddTip + HornAddBase + 2*Protrusion;
HornLength = 12.0; // should recompute ODs, but *eh*
TrimHeight = 2.5; // vertical clearance for spring clip on base plate
// OEM = 2.5
// generic A = 2.5
TrimInset = 1.5; // ... horizontal
// OEM = 0.0
// generic A = 1.5
ScrewOD = 3.0 - 0.25; // screw hole dia - minimal thread engagement
ScrewLength = 11.0;
ScrewOffset = -1.5; // ... from centerline
// OEM = 0.0
// generic A = -1.5
NutOD = 5.6; // hex nut dia across flats
NutThick = 2.4; // ... then add 50% to trap for thread engagement & epoxy
NutOffset = 6.0; // ... base height from floor
VentDia = 2.0; // air vent from back of screw recess
PinOD = 1.72; // alignment pins
PinLength = 6.0;
PinInset = 0.6*SpringRadius; // from outside edges
echo(str("Alignment pin length: ",PinLength));
NumSides = 8*4; // default cylinder sides
Offset = 5.0/2; // from centerline for build layout
//----------------------
// Useful routines
function Delta(a,l) = l*tan(a); // incremental length due to angle
// Locating pin hole with glue recess
// Default length is two pin diameters on each side of the split
module LocatingPin(Dia=PinOD,Len=0.0) {
PinLen = (Len != 0.0) ? Len : (4*Dia);
translate([0,0,-ThreadThick])
PolyCyl((Dia + 2*ThreadWidth),2*ThreadThick,4);
translate([0,0,-2*ThreadThick])
PolyCyl((Dia + 1*ThreadWidth),4*ThreadThick,4);
translate([0,0,-(Len/2 + ThreadThick)])
PolyCyl(Dia,(Len + 2*ThreadThick),4);
}
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);
}
module ShowPegGrid(Space = 10.0,Size = 1.0) {
Range = floor(50 / Space);
for (x=[-Range:Range])
for (y=[-Range:Range])
translate([x*Space,y*Space,Size/2])
%cube(Size,center=true);
}
//----------------------
// The magazine block
module Block(SectionSelect = 0) {
CropHeight = Height*cos(Angle); // block height perpendicular to base
echo(str("Perpendicular height: ",CropHeight));
difference() {
union() {
intersection() {
rotate([Angle,0,0])
hull() {
for (i=[-1,1])
translate([0,i*RectLength/2,-((Length/2)*sin(Angle) + Protrusion)]) cylinder(r=SpringRadius,
h=(Height + 2*(Length/2)*sin(Angle) + 2*Protrusion),
$fn=NumSides);
}
translate([0,0,CropHeight/2])
cube([2*SpringID,3*Length,CropHeight],center=true);
}
translate([0,-Height*sin(Angle),Height*cos(Angle)])
resize([SpringID,0,0])
intersection() {
rotate([Angle,0,0])
translate([0,0,-(HornAddBase + Protrusion)])
cylinder(r1=HornBaseOD/2,
r2=HornTipOD/2,
h=(HornLength + HornAddLength + Protrusion),
$fn=NumSides);
cube([2*SpringID,Length,2*(HornLength*cos(Angle) + Protrusion)],center=true);
}
}
translate([0,ScrewOffset,-Protrusion]) // screw
rotate(180/6)
PolyCyl(ScrewOD,(ScrewLength + Protrusion),6);
translate([0,ScrewOffset,NutOffset]) // nut trap in center
rotate(180/6)
PolyCyl(NutOD,1.5*NutThick,6);
translate([0,ScrewOffset,-Protrusion]) // nut clearance at base
rotate(180/6)
PolyCyl(NutOD,(1.1*NutThick + Protrusion),6);
translate([SpringID/2,-((Length/2)/cos(Angle) - TrimInset),-Protrusion])
rotate(180)
cube([SpringID,2*TrimInset,(TrimHeight + Protrusion)],center=false);
if (AlignPins) // alignment pins
for (i=[-1,1])
rotate([Angle,0,0])
translate([0,
(i*((Length/2)*cos(Angle) - PinInset)),
(CropHeight/2 - i*2*PinInset)])
rotate([0,90,0]) rotate(45 - Angle)
LocatingPin(PinOD,PinLength);
translate([0,(ScrewOffset - NutOD),-Protrusion]) // air vent
rotate(180/8)
PolyCyl(VentDia,(ScrewLength + Protrusion),8);
translate([0,(ScrewOffset + VentDia/2),ScrewLength])
rotate([90,0,0]) rotate(180/8)
PolyCyl(VentDia,(NutOD + VentDia),8);
if (SectionSelect == 1)
translate([0*SpringID,-2*Length,-Protrusion])
cube([2*SpringID,4*Length,(Height + HornLength + 2*Protrusion)],center=false);
else if (SectionSelect == -1)
translate([-2*SpringID,-2*Length,-Protrusion])
cube([2*SpringID,4*Length,(Height + HornLength + 2*Protrusion)],center=false);
}
NumBars = floor((SpringID/2)/(5*ThreadWidth));
if (Support) { // add support structures
for (i = [-NumBars:NumBars])
translate([i*5*ThreadWidth,
-((Length/2)/cos(Angle) + TrimInset/2 + ThreadWidth),
(TrimHeight - ThreadThick)/2])
color("Yellow")
cube([(2*ThreadWidth),(3*TrimInset),(TrimHeight - ThreadThick)],center=true);
translate([-SpringID/2,-((Length/2)/cos(Angle) + 2*TrimInset + ThreadWidth),0])
color("Yellow")
cube([SpringID,(2*ThreadWidth),(TrimHeight - ThreadThick)],center=false);
translate([0,ScrewOffset,0])
for (j=[0:5]) {
rotate(30 + 360*j/6)
translate([(NutOD/2 - ThreadWidth)/2,0,(1.1*NutThick - ThreadThick)/2])
color("Yellow")
cube([(NutOD/2 - ThreadWidth),
(2*ThreadWidth),
(1.1*NutThick - ThreadThick)],
center=true);
}
}
}
//-------------------
// Build it...
ShowPegGrid();
if (Layout == "Show")
Block(1);
if (Layout == "Whole")
Block(0);
if (Layout == "Split") {
translate([(Offset + Length/2),Height/2,0])
rotate(90) rotate([0,-90,-Angle])
Block(-1);
translate([-(Offset + Length/2),Height/2,0])
rotate(-90) rotate([0,90,Angle])
Block(1);
}
A Home Shop Machinist article (A Speed Key for Your Four-Jaw Chuck, p 67 Nov-Dec 2013, David Morrow) showed some lovely knurled steel knobs. These 3D printed knobs aren’t nearly as pretty, but they do much the same thing:
The solid model resembles the illegitimate offspring of a wine bottle and a pineapple:
The knurling comes from aubenc’s Knurled Surface Library v2. I ran off a prototype (on the left), then tweaked the dimensions to get the final version on the right:
Being that type of guy, I define the knurl in terms of its diametral pitch, compute the diamond width & length to fit in the available space, then hand those measurements to the knurling library… which recomputes everything and decides on one less diamond than I do: NumSides has a Finagle Constant of -1 to make the answer come out right. We may be using a different diameter or something, but I haven’t deciphered the source code. It’s parametric out the wazoo, as usual, so you can spin up what you like, how you like it.
Anyhow, a 24 DP knurl with 1.0 mm depth looks and feels pretty good; the XY resolution isn’t good enough for a 48 DP knurl around that knob diameter. The diamonds don’t come out as crisp and pointy as crushed steel knurls, but they’re OK for my fingers.
Doing half a dozen doesn’t take much longer than doing a few, because there’s a 20 second minimum layer time in effect and those things don’t have much plastic, so now I have one for the hold-down clamps and another for Show-n-Tell sessions:
I chopped a 5/32 inch hex key into five 15 mm lengths with a Dremel cutoff wheel, then filed both ends flat and broke the edges. The hex stubs were a press fit in the hex holes, so I finger-started them, grabbed the hex in the drill press, aligned the handle below, and rammed the stub about 5 mm deep. The final depth comes from jamming the wrench into the chuck and pressing firmly, so the stubs project exactly as far as possible:
One might quibble about the infill on the end; one may go adjust one’s own printer as one prefers.
There’s 0.1 mm more HoleWindage than usual, because these holes must fix a hex shaft, not a circular pin, and the corners need some clearance. They came out a firm press fit: exactly what’s needed.
They’re no good for final tightening of those chuck jaws, but that’s not their purpose…
The OpenSCAD source code:
// Knurled handles for Sherline hex keys
// Ed Nisley - KE4ZNU - November 2013
use <knurledFinishLib_v2.scad>
//- Extrusion parameters must match reality!
// Print with 2 shells and 3 solid layers
ThreadThick = 0.20;
ThreadWidth = 0.40;
HoleWindage = 0.3; // extra clearance to improve hex socket fit
Protrusion = 0.1; // make holes end cleanly
PI = 3.14159265358979;
inch = 25.4;
//----------------------
// Dimensions
ShaftDia = 10.5; // un-knurled section diameter
ShaftLength = 15.0; // ... length
SocketDia = (5/32) * inch; // hex key size
SocketDepth = 10.0;
KnurlLen = 20.0; // length of knurled section
KnurlDia = 15.0; // ... diameter
KnurlDPNom = 24; // Nominal diametral pitch = (# diamonds) / (OD inches)
DiamondDepth = 1.0; // ... depth of diamonds
DiamondAspect = 2; // length to width ratio
NumDiamonds = floor(KnurlDPNom * KnurlDia / inch);
echo(str("Num diamonds: ",NumDiamonds));
NumSides = 4*(NumDiamonds - 1); // 4 facets per diamond. Library computes diamonds separately!
KnurlDP = NumDiamonds / (KnurlDia / inch); // actual DP
echo(str("DP Nom: ",KnurlDPNom," actual: ",KnurlDP));
DiamondWidth = (KnurlDia * PI) / NumDiamonds;
DiamondLenNom = DiamondAspect * DiamondWidth; // nominal diamond length
DiamondLength = KnurlLen / round(KnurlLen/DiamondLenNom); // ... actual
TaperLength = 0.75*DiamondLength;
//----------------------
// Useful routines
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);
}
module ShowPegGrid(Space = 10.0,Size = 1.0) {
Range = floor(50 / Space);
for (x=[-Range:Range])
for (y=[-Range:Range])
translate([x*Space,y*Space,Size/2])
%cube(Size,center=true);
}
//- Build it
ShowPegGrid();
difference() {
union() {
render(convexity=10)
translate([0,0,TaperLength])
knurl(k_cyl_hg=KnurlLen,
k_cyl_od=KnurlDia,
knurl_wd=DiamondWidth,
knurl_hg=DiamondLength,
knurl_dp=DiamondDepth,
e_smooth=DiamondLength/2);
color("Orange")
cylinder(r1=ShaftDia/2,
r2=(KnurlDia - DiamondDepth)/2,
h=(TaperLength + Protrusion),
$fn=NumSides);
color("Orange")
translate([0,0,(TaperLength + KnurlLen - Protrusion)])
cylinder(r2=ShaftDia/2,
r1=(KnurlDia - DiamondDepth)/2,
h=(TaperLength + Protrusion),
$fn=NumSides);
color("Moccasin")
translate([0,0,(2*TaperLength + KnurlLen - Protrusion)])
cylinder(r=ShaftDia/2,h=(ShaftLength + Protrusion),$fn=NumSides);
}
translate([0,0,(2*TaperLength + KnurlLen + ShaftLength - SocketDepth + Protrusion)])
PolyCyl(SocketDia,(SocketDepth + Protrusion),6);
}
This might be a good stocking stuffer for that guy who has everything, but you’d need his shop to make it, so what’s the point in that?
The trio of batteries I built for the Sony DSC-F505V two years ago faded away; that camera seems particularly hard on the batteries, perhaps because they’re two cells in parallel that don’t share well. Two of the three seem pretty well gone:
Back then, I bought 12 cells, built six into those batteries, and left six charged cells sitting in a bag. After rebuilding the two worst batteries with those new-old-stock cells, it seems they maintained a substantial fraction of their charge while resting in the cool and the dark:
However, the camera would regard them as discharged, because it infers charge state from voltage. Squinting at the curves, their condition after a few minutes is roughly equal to a new & freshly charged battery produces over on the right when it’s nearly discharged.
The other curves show the result after their first charge in two years: basically, full capacity. The fact that both pairs of curves come pretty close to overlaying means they’re still well matched.
The third cell isn’t up to their spec, but it’s close enough to not bother rebuilding right now: 1.2 vs 1.4 A·h.
The Kapton tape pull tabs work wonderfully well, as the rebuilt batteries fit the compartment rather more snugly than the un-hacked cases.
One of the junker NB-5L eBay batteries for my Canon SX-230HS pocket camera gave up, but the other two have some usable capacity left. The OEM Canon battery seems to be doing fine, perhaps because it sees a relatively low duty cycle:
Compare those curves with the previous tests:
I harvested the weakest of the four junkers to make that dummy battery.
It’s about time to pick up a few more junkers: alas, I can find no bare cells in a size to fit that case.
The general idea is to reduce the capacity of a 13 round Browning Hi-Power magazine to 10 rounds, in compliance with the NY Safe Act, using a number of possibly invalid assumptions. The new Firearms tag will produce earlier posts.
This early prototype tried out the sizes, shapes, and angles, using an M3x0.5 socket head cap screw:
The bottom nut trap locates the block on the inner floor plate by capturing the nut. It might need a bit more clearance or a chamfer to allow for brazing material around the nut flats; cleaning up the brazed nut with a file might also help.
The central trap holds a nut that anchors the block; the trap must be about 50% longer than the nut to allow for thread alignment, because the central hole is a loose tap fit.
That central nut probably isn’t needed, because you’d fill the central shaft with metal-loaded epoxy, which would form a perfectly serviceable, exactly form-fitting, and utterly non-removable “nut”. The vent from the end of the screw shaft releases air trapped behind the epoxy by the screw; if you don’t have a vent, then air pressure will force the epoxy out of the cavity.
If the epoxy “nut” is workable, then you can build it in a single piece printed vertically on the platform. Having a split version makes it easier to show off and, in truth, the cemented joint is about as strong as the rest of the object.
Hot off the M2 3D printer, it looks like this:
A few threads droop into the air vent, so that channel should be larger. The overall plastic block may be porous enough to release the air pressure even without a vent.
With locating pins glued in place and a nut in the central trap:
Pretty much as I expected, it doesn’t quite fit in the magazine, because it doesn’t have clearance for the little tab on the inner floor plate that captures the spring.
One might argue that a plastic block isn’t “permanent”, but it’s definitely not “readily” removed:
This is a start…
The OpenSCAD source code, replete with inadequacies:
// Browning Hi-Power Magazine Plug
// Ed Nisley KE4ZNU November 2013
Layout = "Show"; // Show Whole Pin Build
CrossSection = 1; // -1, 0, 1 to select section side or none
Section = (Layout == "Build") ? 1 : CrossSection; // for cross-section for build
//- Extrusion parameters must match reality!
// Print with 2 shells and 3 solid layers
ThreadThick = 0.25;
ThreadWidth = 0.40;
HoleWindage = 0.2;
Protrusion = 0.1; // make holes end cleanly
//----------------------
// Dimensions
Angle = 12.5; // from vertical
EndDia = 10.3; // an 11/32 inch drill fits
EndRadius = EndDia / 2;
Length = 24.0; // front-to-back perpendicular to magazine shaft
Height = 14.0; // bottom-to-top, parallel to magazine shaft
// 14 = 10 round capacity
// 28 = 7 round
RectLength = Length - EndDia; // block length between end radii
ScrewOD = 3.0 - 0.5; // bottom screw tapping diameter
ScrewLength = 11.0;
ScrewOffset = 0; // ... from centerline
NutOD = 5.5; // hex nut dia across flats
NutThick = 2.4; // ... then add 50% for thread engagement & epoxy
NutOffset = 6.0; // ... base height from floor
VentWidth = 2*ThreadWidth; // air vent from back of screw recess
VentDepth = 4*ThreadThick;
NumSides = 8*4; // default cylinder sides
PinOD = 1.72; // alignment pins
PinLength = 6.0;
PinInset = 0.9*EndRadius; // from outside edges
echo(str("Alignment pin length: ",PinLength));
Offset = 5.0/2; // from centerline for build layout
//----------------------
// Useful routines
// Locating pin hole with glue recess
// Default length is two pin diameters on each side of the split
module LocatingPin(Dia=PinOD,Len=0.0) {
PinLen = (Len != 0.0) ? Len : (4*Dia);
translate([0,0,-ThreadThick])
PolyCyl((Dia + 2*ThreadWidth),2*ThreadThick,4);
translate([0,0,-2*ThreadThick])
PolyCyl((Dia + 1*ThreadWidth),4*ThreadThick,4);
translate([0,0,-(Len/2 + ThreadThick)])
PolyCyl(Dia,(Len + 2*ThreadThick),4);
}
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);
}
module ShowPegGrid(Space = 10.0,Size = 1.0) {
Range = floor(50 / Space);
for (x=[-Range:Range])
for (y=[-Range:Range])
translate([x*Space,y*Space,Size/2])
%cube(Size,center=true);
}
//----------------------
// Components
module Block(SectionSelect = 0) {
Delta = tan(Angle)*(Length/2); // incremental length due to angle
CropHeight = Height*cos(Angle); // block height perpendicular to base
echo(str("Perpendicular height: ",CropHeight));
difference() {
intersection() {
rotate([Angle,0,0])
difference() {
translate([0,0,-Height/2])
linear_extrude(height=2*Height,convexity=2) {
for (i=[-1,1])
translate([0,(i*RectLength/2),0])
rotate(180/NumSides)
circle(r=EndRadius/cos(180/NumSides),
$fn=NumSides);
square([EndDia,RectLength],center=true);
}
for (i=[-1,1])
translate([0,
(i*(Length/2 - PinInset)),
(CropHeight/2 + i*(CropHeight/2 - PinInset))])
rotate([0,90,0]) rotate(45-Angle)
LocatingPin(PinOD,PinLength);
}
translate([0,0,CropHeight/2])
cube([2*EndDia,3*Length,CropHeight],center=true);
}
translate([0,ScrewOffset,-Protrusion]) // screw
rotate(180/6)
PolyCyl(ScrewOD,(ScrewLength + Protrusion),6);
translate([0,ScrewOffset,NutOffset]) // nut trap in center
rotate(180/6)
PolyCyl(NutOD,1.5*NutThick,6);
translate([0,ScrewOffset,-Protrusion]) // nut clearance at base
rotate(180/6)
PolyCyl(NutOD,(1.1*NutThick + Protrusion),6);
translate([0,-(ScrewOffset + NutOD),(ScrewLength - Protrusion)/2]) // air vent
cube([VentDepth/2,VentWidth,(ScrewLength + Protrusion)],center=true);
translate([0,(ScrewOffset - NutOD/2),(ScrewLength - VentWidth/2)])
cube([VentDepth/2,NutOD,VentWidth],center=true);
if (SectionSelect == 1)
translate([EndDia,0,Height/2-Protrusion])
cube([2*EndDia,3*Length,Height+2*Protrusion],center=true);
else if (SectionSelect == -1)
translate([-EndDia,0,Height/2-Protrusion])
cube([2*EndDia,3*Length,Height+2*Protrusion],center=true);
}
}
//-------------------
// Build it...
ShowPegGrid();
if (Layout == "Pin")
LocatingPin(PinOD,PinLength);
if (Layout == "Show")
Block(CrossSection);
if (Layout == "Whole")
Block(0);
if (Layout == "Build") {
translate([(Offset + Length/2),Height/2,0])
rotate(90) rotate([0,-90,-Angle])
Block(-1);
translate([-(Offset + Length/2),Height/2,0])
rotate(-90) rotate([0,90,Angle])
Block(1);
}
The Smell of Molten Projects in the Morning 