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.
Fabric arts and machines
Mary bound up a mesh cover for the shelter frame and deployed it to protect some yummy seedlings:
Those will become the next round of lunchtime sandwiches:
It’s a quarter-pounder: 4 oz of turkey, 4 oz of lettuce, and a layer of Swiss and good stinky Provolone cheese. Yum!
Mary’s most recent quilt arranges her color choices in Judy Niemeyer’s Stellar Snowflake pattern:
Her Juki TL-2010Q sewing machine has a built-in thread cutter activated by pressing down on the heel end (to the left) of the foot control:
The machine had previously performed “uncommanded” thread cuts on other projects, but the many short segments in this pattern triggered far too many cuts. I aimed a camera at her foot on the pedal and she was definitely not pressing down with her heel when the cutter fired.
In point of fact, the thread cutter fired when she was just starting a new segment, where she was gently pressing down on the toe end (to the right) of the pedal to start at the slowest possible speed.
For completeness, the underside of the pedal:
There are no screws holding it together. The top cover pivots on a pair of plastic pegs sticking out from the base near the middle of the cable spool. Disassembly requires jamming a pair of husky Prydrivers in there and applying enough brute force to pry both sides outward farther than you (well, I) think they should bend. This will scar the bottom of the case, but nobody will ever notice.
The foot control cable plugs into the machine through what looks like an ordinary two-conductor coax plug, just like the ones on wall warts delivering power to gadgets around the house. In this day and age, the communications protocol could be anything from a simple resistor to a full-frontal 1-Wire encrypted data exchange.
Based on the old Kenmore foot pedals, I expected a resistive control and, indeed, a simple test gave these results:
We can all see where this is going, but just to be sure I pried the top off the control to reveal the insides:
The two cylindrical features capture the ends of a pair of stiff compression springs pressing the top of the pedal upward.
The small, slightly stretched, extension spring in the middle pulls the slider to the left (heelward), with a ramp in the top cover forcing it to the right (toeward) as the speed increases.
The top cover includes a surprisingly large hunk of metal which may provide enough mass to make the pedal feel good:
The ramp is plastic and the slider has a pair of nylon (-ish) rollers, so there’s not much friction involved in the speed control part of motion. Yes, this is oriented the other way, with the heel end over on the right.
The metal insert pivots in the serrated plastic section near the middle, with the two husky extension springs visible on the left holding it against the plastic cover. The two rectangular features on the left rest under the plastic flanges on the right of the base to prevent the metal insert from moving upward, so pressing the heel end down pulls the cover away from the insert to let the slider rollers move toward the right end of the ramp, into roughly the position shown in the interior view.
A closeup look at the slider shows the rollers and the PCB holding all of the active ingredients:
I think the trimpot adjusts the starting resistance for the slider’s speed control travel. It is, comfortingly, roughly in the middle of its range.
A top view shows the fixed 140 kΩ resistor (brown yellow black orange, reading from the right) setting the idle resistance:
Measuring the resistance while gently teasing the slider showed that it’s possible to produce a resistance higher than 20 kΩ and lower than 140 kΩ, although it requires an exceedingly finicky touch and is completely unstable.
Before looking inside the pedal, we thought the cutter was triggered by an actual switch closure with the heel end most of the way downward against those stiff springs, which meant the failure came from a switch glitch. Now, we think the earlier and infrequent uncommanded thread cuts trained Mary to start very carefully to be very sure she wasn’t glitching the cutter’s hypothetical switch. Of course, her gradually increasing toe pressure moved the slider very slowly through its idle-to-running transition: she was optimizing her behavior to produce exactly the resistance required to trigger the cutter.
She now sets the machine’s speed control midway between Turtle and Hare to limit its top speed, presses the pedal with more confidence to minimize the time spent passing through the danger zone, and has had far few uncommanded thread cuts. We think it’s now a matter of retraining her foot to stomp with conviction; there’s no hardware or software fix.
I’m sure Juki had a good reason to select the resistances they did, but I would have gone for a non-zero minimum resistance at the fast end of travel and a zero-resistance switch to trigger the cutter.
We got a photo backdrop stand to hold Mary’s show-n-tell quilts during her quilting club meetings, but the clamps intended to hold the backdrop from the top bar don’t work quite the way one might expect. These photos snagged from the listing shows their intended use:
The clamp closes on the top bar with the jaws about 15 mm apart, so you must wrap the backdrop around the bar, thereby concealing the top few inches of whatever you intended to show. This doesn’t matter for a preprinted generic backdrop or a green screen, but quilt borders have interesting detail.
The clamps need thicker jaws, which I promptly conjured from the vasty digital deep:
The original jaws fit neatly into those recesses, atop a snippet of carpet tape to prevent them from wandering off:
They’re thick enough to meet in the middle and make the clamp’s serrated round-ish opening fit around the bar:
With a quilt in place, the clamps slide freely along the bar:
That’s a recreation based on actual events, mostly because erecting the stand wasn’t going to happen for one photo.
To level set your expectations, the “Convenient Carry Bag” is more of a wrap than a bag, without enough fabric to completely surround its contents:
I put all the clamps / hooks / doodads in a quart Ziploc baggie, which seemed like a better idea than letting them rattle around loose inside the wrap. The flimsy pair (!) of hook-n-loop straps don’t reach across the gap and, even extended with a few inches of double-sided Velcro, lack enough mojo to hold it closed against all the contents.
It’ll suffice for our simple needs, but …
The OpenSCAD source code as a GitHub Gist:
| // Clamp pads for Emart photo backdrop clamps | |
| // Ed Nisley KE4ZNU Jan 2021 | |
| /* [Hidden] */ | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; // make holes end cleanly | |
| inch = 25.4; | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes | |
| Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2); | |
| FixDia = Dia / cos(180/Sides); | |
| cylinder(d=(FixDia + HoleWindage),h=Height,$fn=Sides); | |
| } | |
| //———————- | |
| // Dimensions | |
| OEMpad = [24.0,16.0,3.0]; // original pad | |
| Pad = [35.0,25.0,8.0 + OEMpad.z]; // pad extension | |
| PadOffset = [0,-3.0,0]; | |
| CornerRad = 3.0; // corner rounding | |
| Gap = 3.0; | |
| //———————- | |
| // Shape the pad | |
| module BigPad() { | |
| difference() { | |
| hull() | |
| for (i=[-1,1],j=[-1,1],k=[-1,1]) | |
| translate([i*(Pad.x/2 – CornerRad),j*(Pad.y/2 – CornerRad),k*(Pad.z/2 – CornerRad) + Pad.z/2]) | |
| sphere(r=CornerRad,$fn=6); | |
| translate(PadOffset + [0,0,Pad.z – (OEMpad.z + Protrusion)/2]) | |
| cube(OEMpad + [HoleWindage,HoleWindage,Protrusion],center=true); | |
| } | |
| } | |
| //———————- | |
| // Build a pair | |
| translate([0,(Pad.y + Gap)/2,0]) | |
| BigPad(); | |
| translate([0,-(Pad.y + Gap)/2,0]) | |
| rotate(180) | |
| BigPad(); | |
Although I was blithely unaware when I bought some useful-looking surplus, it turns out 1/16 inch armature wire works really well to seal our homebrew masks around our noses. Mary added a narrow passage along the top edge of her slightly reshaped Fu Mask pattern to retain the wire and I provided 4.5 inch lengths of straightened wire:
The wire comes off the roll in dead-soft condition, so I can straighten (and slightly harden) it by simply rolling each wire with eight fingertips across the battered cutting board. The slightly wavy wire shows its as-cut condition and the three straight ones are ready for their masks.
Although nearly pure aluminum wire doesn’t work-harden quickly, half a year of mask duty definitely takes its toll. This sample came from my biking mask after the edges wore out:
We initially thought using two wires would provide a better fit, but more metal just made adjusting the nose seal more difficult after each washing. The wire has work-hardened enough to make the sharper bends pretty much permanent; they can be further bent, but no longer roll out under finger pressure.
Although we’re not yet at the point where we must reuse wires, I took this as an opportunity to improve my annealing hand: heat the wire almost to its melting point, hold it there for a few seconds, then let it cool slowly. The usual technique involves covering the aluminum with something like hand soap or permanent marker ink, heat until the soap / marker burns away, then let it air-cool. Unlike steel, there’s no need for quenching or tempering.
Blue Sharpie worked surprisingly well with a propane torch:
As far as I can tell after a few attempts, the pigment vanishes just below the annealing temperature and requires another pass to reach the right temperature. Sweep the flame steadily, don’t pause, and don’t hold the wire over anything melt-able.
Those wires (I cut the doubled wire apart) aren’t quite as soft as the original stock, but they rolled straight and are certainly good enough for our simple needs; they’re back in the Basement Laboratory Warehouse for future (re)use.
Although I’d put the same knob on the half-triangle end piece template as on the equilateral triangle template for piecing hexagons into strips, Mary decided a flat chip would be easier to use:
Bonus: you can now flip it over to cut the other half-triangles, if you haven’t already figured out how to cut two layers of fabric folded wrong sides together.
While I was at it, the knob on the triangle became optional, too. Flipping that one doesn’t buy you much, though.
The OpenSCAD source as a GitHub Gist has been ever so slightly tweaked:
| // Quilting – Hexagon Templates | |
| // Ed Nisley KE4ZNU – July 2020 | |
| // Reverse-engineered to repair a not-quite-standard hexagon quilt | |
| // Useful geometry: | |
| // https://en.wikipedia.org/wiki/Hexagon | |
| /* [Layout Options] */ | |
| Layout = "Build"; // [Build, HexBuild, HexPlate, TriBuild, TriPlate, EndBuild, EndPlate] | |
| //——- | |
| //- Extrusion parameters must match reality! | |
| // Print with 2 shells | |
| /* [Hidden] */ | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| HoleFinagle = 0.2; | |
| HoleFudge = 1.00; | |
| function HoleAdjust(Diameter) = HoleFudge*Diameter + HoleFinagle; | |
| Protrusion = 0.1; // make holes end cleanly | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| inch = 25.4; | |
| //——- | |
| // Dimensions | |
| /* [Layout Options] */ | |
| FinishedWidthInch = 2.75; | |
| FinishedWidth = FinishedWidthInch * inch; | |
| SeamAllowanceInch = 0.25; | |
| SeamAllowance = SeamAllowanceInch * inch; | |
| TemplateThick = 3.0; | |
| TriKnob = true; | |
| EndKnob = false; | |
| /* [Hidden] */ | |
| FinishedSideInch = FinishedWidthInch/sqrt(3); | |
| FinishedSide = FinishedSideInch * inch; | |
| echo(str("Finished side: ",FinishedSideInch," inch")); | |
| CutWidth = FinishedWidth + 2*SeamAllowance; | |
| CutSide = CutWidth/sqrt(3); | |
| echo(str("Cut side: ",CutSide / inch," inch")); | |
| // Make polygon-circles circumscribe the target widths | |
| TemplateID = FinishedWidth / cos(180/6); | |
| TemplateOD = CutWidth / cos(180/6); | |
| /* [Hidden] */ | |
| TriRadius = FinishedSide/sqrt(3); | |
| TriPoints = [[TriRadius,0], | |
| [TriRadius*cos(120),TriRadius*sin(120)], | |
| [TriRadius*cos(240),TriRadius*sin(240)] | |
| ]; | |
| echo(str("TriPoints: ",TriPoints)); | |
| EndPoints = [[TriRadius,0], | |
| [TriRadius*cos(120),TriRadius*sin(120)], | |
| [TriRadius*cos(120),0] | |
| ]; | |
| echo(str("EndPoints: ",EndPoints)); | |
| TipCutRadius = 2*(TriRadius + SeamAllowance); // circumscribing radius of tip cutter | |
| TipPoints = [[TipCutRadius,0], | |
| [TipCutRadius*cos(120),TipCutRadius*sin(120)], | |
| [TipCutRadius*cos(240),TipCutRadius*sin(240)] | |
| ]; | |
| HandleHeight = 1 * inch; | |
| HandleLength = (TemplateID + TemplateOD)/2; | |
| HandleThick = IntegerMultiple(3.0,ThreadWidth); | |
| HandleSides = 12*4; | |
| StringDia = 4.0; | |
| StringHeight = 0.6*HandleHeight; | |
| DentDepth = HandleThick/4; | |
| DentDia = 15 * DentDepth; | |
| DentSphereRadius = (pow(DentDepth,2) + pow(DentDia,2)/4)/(2*DentDepth); | |
| KnobOD = 15.0; // Triangle handle | |
| KnobHeight = 20.0; | |
| //——- | |
| 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=HoleAdjust(FixDia)/2,h=Height,$fn=Sides); | |
| } | |
| //——- | |
| // Hex template | |
| module HexPlate() { | |
| difference() { | |
| cylinder(r=TemplateOD/2,h=TemplateThick,$fn=6); | |
| translate([0,0,-Protrusion]) | |
| cylinder(r=TemplateID/2,h=(TemplateThick + 2*Protrusion),$fn=6); | |
| } | |
| for (i=[1:6/2]) | |
| rotate(i*60) | |
| translate([0,0,TemplateThick/2]) | |
| cube([HandleLength,HandleThick,TemplateThick],center=true); | |
| } | |
| module HexHandle() { | |
| difference() { | |
| rotate([90,0,0]) | |
| scale([1,HandleHeight/(TemplateOD/2),1]) | |
| rotate(180/HandleSides) | |
| cylinder(d=HandleLength,h=HandleThick,center=true,$fn=HandleSides); | |
| translate([0,0,-HandleHeight]) | |
| cube([2*TemplateOD,2*TemplateOD,2*HandleHeight],center=true); | |
| translate([0,HandleThick,StringHeight]) | |
| rotate([90,090,0]) | |
| rotate(180/8) | |
| PolyCyl(StringDia,2*HandleThick,8); | |
| for (j=[-1,1]) { | |
| translate([0,j*(DentSphereRadius + HandleThick/2 – DentDepth),StringHeight]) | |
| rotate(180/48) | |
| sphere(r=DentSphereRadius,$fn=48); | |
| } | |
| } | |
| } | |
| module HexTemplate() { | |
| HexPlate(); | |
| HexHandle(); | |
| } | |
| //——- | |
| // Triangle template | |
| module TriPlate() { | |
| linear_extrude(height=TemplateThick) | |
| intersection() { | |
| offset(delta=SeamAllowance) // basic cutting outline | |
| polygon(points=TriPoints); | |
| rotate(180) | |
| polygon(points=TipPoints); | |
| } | |
| } | |
| module TriTemplate() { | |
| union() { | |
| if (TriKnob) | |
| cylinder(d=KnobOD,h=KnobHeight,$fn=HandleSides); | |
| TriPlate(); | |
| } | |
| } | |
| //——- | |
| // End piece template | |
| module EndPlate() { | |
| linear_extrude(height=TemplateThick) | |
| intersection() { | |
| offset(delta=SeamAllowance) // basic cutting outline | |
| polygon(points=EndPoints); | |
| rotate(180) | |
| polygon(points=TipPoints); | |
| } | |
| } | |
| module EndTemplate() { | |
| union() { | |
| if (EndKnob) | |
| translate([0,(TriRadius/2)*sin(30),0]) | |
| cylinder(d=KnobOD,h=KnobHeight,$fn=HandleSides); | |
| EndPlate(); | |
| } | |
| } | |
| //——- | |
| // Build it! | |
| if (Layout == "HexPlate") | |
| HexPlate(); | |
| if (Layout == "HexBuild") | |
| HexTemplate(); | |
| if (Layout == "TriPlate") | |
| TriPlate(); | |
| if (Layout == "TriBuild") | |
| TriTemplate(); | |
| if (Layout == "EndPlate") | |
| EndPlate(); | |
| if (Layout == "EndBuild") | |
| EndTemplate(); | |
| if (Layout == "Build") { | |
| translate([1.5*TriRadius,-TriRadius,0]) | |
| rotate(180/6) | |
| TriTemplate(); | |
| translate([-1.5*TriRadius,-TriRadius,0]) | |
| rotate(180/6) | |
| EndTemplate(); | |
| translate([0,TemplateOD/2,0]) | |
| HexTemplate(); | |
| } |
Mary took on the task of finishing a hexagonal quilt from pieced strips, only to discover she’ll need several more strips and the myriad triangles required to turn hexagons into strips. The as-built strips do not match any of the standard pattern sizes, which meant ordinary templates were unavailing. I offered to build a template matching the (average) as-built hexagons, plus a triangle template based on those dimensions.
Wikipedia has useful summaries of hexagon and equilateral triangle geometry and equations.
Quilters measure hexes based on their finished side length, so a “1 inch hex” has sides measuring 1 inch, with the seam allowance extending ¼ inch beyond the sides. It’s difficult to measure finished sides with sufficient accuracy, so we averaged the side-to-side distance across several hexes.
Some thrashing around produced a quick-and-dirty check piece that matched (most of) the stack of un-sewn hexes:
That one came from a knockoff of the circle template, after some cleanup & tweakage, but failed user testing for not withstanding the side force from the rotary cutter blade. The inside and outside dimensions were correct, however, so I could proceed with some confidence I understood the geometry.
Both the pattern width (the side-to-side distance across the inside of the hex) and the seam allowance appearing in the Customizer appear in inches, because that’s how things get measured outside the Basement Laboratory & Fabrication Facility:
FinishedWidthInch = 2.75;
FinishedWidth = FinishedWidthInch * inch;
SeamAllowanceInch = 0.25;
SeamAllowance = SeamAllowanceInch * inch;You feed in one side-to-side measurement and all other hex dimensions get calculated from that number; quilters default to a ¼ inch seam allowance. Remember, standard quilt hexes are measured by their side length, so just buy some standard templates.
This is one of the few times I’ve needed triangle graph paper:
After I gave up trying to get it right on square-grid paper, of course.
Solidifying those relations:
Both templates have non-skid strips to keep the fabric in place while cutting:
I should have embossed the size on each template, but this feels like a one-off project and YAGNI. Of course, that’s how I felt about the circle templates, so maybe next time I’ll get it right.
As it turned out, Mary realized she needed a template for the two half-triangles at the end of each row:
It’s half of the finished size of the equilateral triangle on the right, with seam allowance added all around. The test scrap of fabric on the left shows the stitching along the hypotenuse of the half-triangle, where it joins to the end-of-row hexagon. Ideally, you need two half-triangle templates, but Mary says it’s easier to cut the fabric from the back side than to keep track of two templates.
The family portrait now has three members:
The OpenSCAD source code as a GitHub Gist:
| // Quilting – Hexagon Templates | |
| // Ed Nisley KE4ZNU – July 2020 | |
| // Reverse-engineered to repair a not-quite-standard hexagon quilt | |
| // Useful geometry: | |
| // https://en.wikipedia.org/wiki/Hexagon | |
| /* [Layout Options] */ | |
| Layout = "Build"; // [Build, HexBuild, HexPlate, TriBuild, TriPlate, EndBuild, EndPlate] | |
| //——- | |
| //- Extrusion parameters must match reality! | |
| // Print with 2 shells | |
| /* [Hidden] */ | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| HoleFinagle = 0.2; | |
| HoleFudge = 1.00; | |
| function HoleAdjust(Diameter) = HoleFudge*Diameter + HoleFinagle; | |
| Protrusion = 0.1; // make holes end cleanly | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| inch = 25.4; | |
| //——- | |
| // Dimensions | |
| /* [Layout Options] */ | |
| FinishedWidthInch = 2.75; | |
| FinishedWidth = FinishedWidthInch * inch; | |
| SeamAllowanceInch = 0.25; | |
| SeamAllowance = SeamAllowanceInch * inch; | |
| TemplateThick = 3.0; | |
| TriKnob = true; | |
| EndKnob = false; | |
| /* [Hidden] */ | |
| FinishedSideInch = FinishedWidthInch/sqrt(3); | |
| FinishedSide = FinishedSideInch * inch; | |
| echo(str("Finished side: ",FinishedSideInch," inch")); | |
| CutWidth = FinishedWidth + 2*SeamAllowance; | |
| CutSide = CutWidth/sqrt(3); | |
| echo(str("Cut side: ",CutSide / inch," inch")); | |
| // Make polygon-circles circumscribe the target widths | |
| TemplateID = FinishedWidth / cos(180/6); | |
| TemplateOD = CutWidth / cos(180/6); | |
| /* [Hidden] */ | |
| TriRadius = FinishedSide/sqrt(3); | |
| TriPoints = [[TriRadius,0], | |
| [TriRadius*cos(120),TriRadius*sin(120)], | |
| [TriRadius*cos(240),TriRadius*sin(240)] | |
| ]; | |
| echo(str("TriPoints: ",TriPoints)); | |
| EndPoints = [[TriRadius,0], | |
| [TriRadius*cos(120),TriRadius*sin(120)], | |
| [TriRadius*cos(120),0] | |
| ]; | |
| echo(str("EndPoints: ",EndPoints)); | |
| TipCutRadius = 2*(TriRadius + SeamAllowance); // circumscribing radius of tip cutter | |
| TipPoints = [[TipCutRadius,0], | |
| [TipCutRadius*cos(120),TipCutRadius*sin(120)], | |
| [TipCutRadius*cos(240),TipCutRadius*sin(240)] | |
| ]; | |
| HandleHeight = 1 * inch; | |
| HandleLength = (TemplateID + TemplateOD)/2; | |
| HandleThick = IntegerMultiple(3.0,ThreadWidth); | |
| HandleSides = 12*4; | |
| StringDia = 4.0; | |
| StringHeight = 0.6*HandleHeight; | |
| DentDepth = HandleThick/4; | |
| DentDia = 15 * DentDepth; | |
| DentSphereRadius = (pow(DentDepth,2) + pow(DentDia,2)/4)/(2*DentDepth); | |
| KnobOD = 15.0; // Triangle handle | |
| KnobHeight = 20.0; | |
| //——- | |
| 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=HoleAdjust(FixDia)/2,h=Height,$fn=Sides); | |
| } | |
| //——- | |
| // Hex template | |
| module HexPlate() { | |
| difference() { | |
| cylinder(r=TemplateOD/2,h=TemplateThick,$fn=6); | |
| translate([0,0,-Protrusion]) | |
| cylinder(r=TemplateID/2,h=(TemplateThick + 2*Protrusion),$fn=6); | |
| } | |
| for (i=[1:6/2]) | |
| rotate(i*60) | |
| translate([0,0,TemplateThick/2]) | |
| cube([HandleLength,HandleThick,TemplateThick],center=true); | |
| } | |
| module HexHandle() { | |
| difference() { | |
| rotate([90,0,0]) | |
| scale([1,HandleHeight/(TemplateOD/2),1]) | |
| rotate(180/HandleSides) | |
| cylinder(d=HandleLength,h=HandleThick,center=true,$fn=HandleSides); | |
| translate([0,0,-HandleHeight]) | |
| cube([2*TemplateOD,2*TemplateOD,2*HandleHeight],center=true); | |
| translate([0,HandleThick,StringHeight]) | |
| rotate([90,090,0]) | |
| rotate(180/8) | |
| PolyCyl(StringDia,2*HandleThick,8); | |
| for (j=[-1,1]) { | |
| translate([0,j*(DentSphereRadius + HandleThick/2 – DentDepth),StringHeight]) | |
| rotate(180/48) | |
| sphere(r=DentSphereRadius,$fn=48); | |
| } | |
| } | |
| } | |
| module HexTemplate() { | |
| HexPlate(); | |
| HexHandle(); | |
| } | |
| //——- | |
| // Triangle template | |
| module TriPlate() { | |
| linear_extrude(height=TemplateThick) | |
| intersection() { | |
| offset(delta=SeamAllowance) // basic cutting outline | |
| polygon(points=TriPoints); | |
| rotate(180) | |
| polygon(points=TipPoints); | |
| } | |
| } | |
| module TriTemplate() { | |
| union() { | |
| if (TriKnob) | |
| cylinder(d=KnobOD,h=KnobHeight,$fn=HandleSides); | |
| TriPlate(); | |
| } | |
| } | |
| //——- | |
| // End piece template | |
| module EndPlate() { | |
| linear_extrude(height=TemplateThick) | |
| intersection() { | |
| offset(delta=SeamAllowance) // basic cutting outline | |
| polygon(points=EndPoints); | |
| rotate(180) | |
| polygon(points=TipPoints); | |
| } | |
| } | |
| module EndTemplate() { | |
| union() { | |
| if (EndKnob) | |
| translate([0,(TriRadius/2)*sin(30),0]) | |
| cylinder(d=KnobOD,h=KnobHeight,$fn=HandleSides); | |
| EndPlate(); | |
| } | |
| } | |
| //——- | |
| // Build it! | |
| if (Layout == "HexPlate") | |
| HexPlate(); | |
| if (Layout == "HexBuild") | |
| HexTemplate(); | |
| if (Layout == "TriPlate") | |
| TriPlate(); | |
| if (Layout == "TriBuild") | |
| TriTemplate(); | |
| if (Layout == "EndPlate") | |
| EndPlate(); | |
| if (Layout == "EndBuild") | |
| EndTemplate(); | |
| if (Layout == "Build") { | |
| translate([1.5*TriRadius,-TriRadius,0]) | |
| rotate(180/6) | |
| TriTemplate(); | |
| translate([-1.5*TriRadius,-TriRadius,0]) | |
| rotate(180/6) | |
| EndTemplate(); | |
| translate([0,TemplateOD/2,0]) | |
| HexTemplate(); | |
| } |
My first pass at deglaring the shiny metal parts on Mary’s brightly lit Kenmore 158 used translucent mailing labels on the “hand hole cover” in front of the needle:
That worked surprisingly well for surprisingly long, but the edges eventually came loose and, after far too long, I deployed the Tiny Sandblaster™:
The mottled matte effect isn’t quite what I expected, but it’s better-looking in person and we deemed it Good Enough™ for the purpose.
You saw the foot on the left in the previous effort:
The rounded plate directly under the needle sits far enough back to not reflect any of the LEDs toward her normal operating position, so we decided it didn’t need sandblasting.
She now has plenty of light where she needs it, with no glare from the metal bits.
The Smell of Molten Projects in the Morning 