Tag: Sewing

Fabric arts and machines

Free Motion Quilting Darning Foot Modification: The Home Shop Way

Mary has been learning free motion quilting, which uses a special sewing-machine foot that holds the fabric in place. Leah Day describes modifying a standard darning foot, but I suggested deploying a bit more shop-fu to do it right. The notion of “adjusting” something with a twisted rubber band just made my skin crawl…

The starting point is a Brewer BP1814 “FOOT Darning/Quilting low shank with clear base”, two of which appear next to an older version that she’s had for quite some time. The rightmost one has my modifications:

Brewer BP1814 Quilting Foot – assortment

The older (mostly metal) foot works much better for its intended purpose, but the newer white plastic version seems easier to modify for free-motion quilting. The older spring is much softer than the new ones, for whatever that’s worth. After the modification, the spring pressure becomes largely irrelevant, as it only acts when something pushes up on the base.

The first modification improves visibility by cutting out part of the transparent plastic base. Leah suggests chopping it with a diagonal cutter (“jewelry clippers”), but I deployed a slitting saw in the Dremel tool at low speed to avoid melting. Mary wanted angled cuts, so that’s what she got:

Modified Darning Foot – opened base

A bit of touchup with a fine file smoothed out the edges so the base slides easily over the fabric. There’s no way to remove the red guide lines; the un-modified foot on the left emerged from its bag with that smeared line.

Then drive out the top metal pin with a small drift punch, hold the base and shaft, remove the C-clip, capture the spring, and extract the base and shaft. The 4.0 mm diameter metal shaft cries out to be threaded, so that’s what I did; this picture shows the reassembled shaft and spring:

Modified Darning Foot – threaded shaft

That’s significantly harder to accomplish than it looks, because there’s no practical way to remove the plastic base (it’s pinned in place, but one side of the cross-hole is blocked). I filed the end of the shaft to a taper that started the M4.0x0.7 die a bit more easily, clamped the shaft in the bench vise, applied nasty sulfur-based tapping fluid, crossed my fingers and eyes, held my nose, and managed to make it happen without cracking the plastic.

I reamed out the Nyloc nut with a hand-twisted series of drills, through about #24 = 3.861 mm, to reduce the locking torque. It’s now just slightly more than finger-tight, which should suffice.

In use, the foot fits under the sewing machine’s arm and puts the nut where fingers can’t reach. I filed a 6.0 mm “precision wrench” to fit the 6.8 mm nut flats and it’s All Good:

Modified Darning Foot – assembled with wrench

A staged photo op atop some trial quilting:

Modified Darning Foot – in action

With a Nyloc nut instead of a rubber band, it will stay exactly where she wants it…

2014-01-16
Making Finger Grip Dents: The Chord Equation
The handle of that quilting circle template has a pair of finger grip dents, which, while they aren’t strictly necessary, seemed like a nice touch:

Quilting circle template – solid model

They’re the result of subtracting a pair of spheres from the flat handle:

Quilting circle template – handle dent spheres – solid model

Given:
- m = the depth of the dent
- c = its diameter on the surface of the handle
There’s an easy way to compute R = the radius of the sphere that excavates the dent:

Circle chord vs depth sketch

Thusly:

R = (m² + c²/4) / (2 m)

In OpenSCAD, that goes a little something like this:
```
DentDepth = HandleThick/4;
DentDia = 15.0;
DentSphereRadius = (pow(DentDepth,2) + pow(DentDia,2)/4)/(2*DentDepth);
```
Then generate the sphere (well, two spheres, one for each dent) and offset it to scoop out the dent:
```
for (i=[-1,1]) {
	translate([i*(DentSphereRadius + HandleThick/2 - DentDepth),0,StringHeight])
		sphere(r=DentSphereRadius);
```
HandleThick controls exactly what you’d expect. StringHeight sets the location of the hole punched through the handle for a string, which is also the center of the dents.

The spheres have many facets, but only a few show up in the dent. I like the way the model looks, even if the facets don’t come through clearly in the plastic:

Quilting circle template – handle dent closeup – solid model

It Just Works and the exact math produces a better result than by-guess-and-by-gosh positioning.

The sphere radius will come out crazy large for very shallow dents. Here’s the helmet plate for my Bicycle Helmet Mirror Mount, which has an indentation (roughly) matching the curve on the side of my bike helmet:

Helmet mirror mount – plate

Here’s the sphere that makes the dent, at a somewhat different zoom scale:

Helmet mirror mount – plate with sphere

Don’t worry: trust the math, because It Just Works.

You find equations like that in Thomas Glover’s invaluable Pocket Ref. If you don’t have a copy, fix that problem right now; I don’t get a cut from the purchase, but you’ll decide you owe me anyway. Small, unmarked bills. Lots and lots of small unmarked bills…
2013-08-02

Quilting Circle Template: Why I Loves Me My 3D Printer(s)

Mary just started an ambitious pieced quilt that requires 50-some-odd precisely sized 1-1/2 inch circles, with marks to locate a 1 inch circle in the middle. She started using a drafting template to mark the smaller circle on freezer paper (don’t ask, it’s complicated), but we couldn’t find the template I know I have with the larger circles.

[Update: It’s a Bittersweet Briar traditional quilt. See all those little dots-for-berries?]

So I says to my wife, I sez, “Hey, we have the technology. What would really simplify what you’re doing?” After a bit of doodling, we came up with a ring having the proper ID and OD, plus a flat handle of some sort.

Half an hour later, I had a solid model:

Quilting circle template - solid model — Quilting circle template – solid model

An hour after that I handed her a warm piece of plastic:

The bottom ring is exactly 1-1/2 inch OD, 1 inch ID, and thin enough to draw around. The handle keeps her fingers out of the way and even has grips and a hole for a string.

The print quality near the hole isn’t as good as I’d like, because the slicer turned that entire volume into a solid slab of plastic. I can fix that in the second version, but right now she has something to work with, evaluate, and figure out what would improve it.

3D printing isn’t for everybody, but it’s a vital part of my shop!

The OpenSCAD source code has parameters for everything, so we can crank out more templates without fuss:

// Quilting - Circle Template
// Ed Nisley KE4ZNU - July 2013

Layout = "Show";                    // Show Build Circle Handle

//-------
//- Extrusion parameters must match reality!
//  Print with 2 shells

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);
function IntegerMultipleMin(Size,Unit) = Unit * floor(Size / Unit);

inch = 25.4;

//-------
// Dimensions

CircleID = (1) * inch;

SeamAllowance = (1/4) * inch;

CircleOD = CircleID + 2*SeamAllowance;

CircleThick = 6*ThreadThick;

CircleSides = 12*4;

HandleHeight = (2) * inch;
HandleThick = IntegerMultiple(5.0,ThreadWidth);
HandleSides = 12*4;

StringDia = 4.0;
StringSides = 8;
StringHeight = 0.75*HandleHeight;

DentDepth = HandleThick/4;
DentDia = 15.0;
DentSphereRadius = (pow(DentDepth,2) + pow(DentDia,2)/4)/(2*DentDepth);

//-------

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);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}

//-------
// Circle ring plate

module CircleRing() {

	rotate(180/CircleSides)
		difference() {
			cylinder(r=CircleOD/2,h=CircleThick,$fn=CircleSides);
			translate([0,0,-Protrusion])
				cylinder(r=CircleID/2,h=(CircleThick + 2*Protrusion),$fn=CircleSides);
		}
}

//-------
// Handle

module Handle() {

	difference() {
		rotate([0,90,0])
			scale([HandleHeight/(CircleOD/2),0.9,1])
				rotate(180/HandleSides)
					cylinder(r=CircleOD/2,h=HandleThick,center=true,$fn=HandleSides);
		translate([0,0,-HandleHeight])
			cube([2*CircleOD,2*CircleOD,2*HandleHeight],center=true);
		translate([-HandleThick,0,StringHeight])
			rotate([0,90,0])
				rotate(180/StringSides)
					PolyCyl(StringDia,2*HandleThick,StringSides);
#		for (i=[-1,1]) {
			translate([i*(DentSphereRadius + HandleThick/2 - DentDepth),0,StringHeight])
				sphere(r=DentSphereRadius);
		}
	}

}

module Template() {
	CircleRing();
	Handle();
}

//-------
// Build it!

ShowPegGrid();

if (Layout == "Circle")
	CircleRing();

if (Layout == "Handle")
	Handle();

if (Layout == "Show")
	Template();

2013-07-30

Quilting Pin Caps: Recycled O-Ring

While doing something else, I rediscovered the fact that common 5 gallon plastic bucket lids have an O-ring gasket that seals against the top of the bucket. Some seals are hollow tubes, some are solid rods:

5 gallon can lid gaskets

The white O-ring has about the right consistency to serve as a quilting pin cap, along the lines of those 3D printed and silicone rubber filled cylinders. Although the rubber / plastic stuff isn’t quite as squishy as silicone snot, it holds the pin point firmly without much of a push.

Chopping the O-ring into 10 mm sections produced another small box of prototypes:

Lid gaskets as pin caps

Garden planting season remains in full effect, shoving all quilting projects to the back burner and delaying the evaluation phase of the project…

2012-06-16
Quilting Pin Caps
Mary has been quilting up a storm lately and is growing dissatisfied with the special safety pins she’s been using to hold the layers together. Long straight pins are ideal, except that maneuvering a large quilt through her sewing machine resembles stuffing a porcupine into a keyhole. A commercial solution costs nearly half a buck per pin, which seems unreasonably spendy for something you need by the hundreds.

We kicked around some finger- and quilt-friendly dimensions and I cobbled up a solid model:

Quilting Pin Cap

Which turned into an array of small octagons that won’t roll off the table:

Pin cap array on build platform

We figured 25 would be enough to decide if this is workable and whether the dimensions fit fingers, pins, and quilts.

Filling them with silicone rubber required one squirt each:

Filling pin caps with silicone

The trick with the silicone rubber is to cut the snout so it fits flat on the cylinder top. Put the cylinders on a piece of non-stick paper (I used the back of the carrier for some double-sided tape, but wax paper would be better), hold one with tweezers, squirt in enough rubber to fill the cylinder solidly from bottom to top, then slide the snout sideways to smooth the surface.

Wait for a day, pop them off, and remove any drool:

Silicone-filled pin caps

It’s garden planting time right now, so it’ll take a while before I tweak the design and run off the next batch.

I don’t know how to compute an actual cost for each of those things. I regard the entire Thing-O-Matic as fully depreciated and pretty much a sunk cost, which means the expense boils down to the incremental cost of plastic and silicone. All the Quality Shop Time is, of course, free… and maybe even therapeutic.

The (trivially simple) OpenSCAD source code:
```
// Quilting pin caps
// Ed Nisley KE4ZNU April 2012

//- Extrusion parameters must match reality!
//  Print with +1 shells and 3 solid layers

ThreadThick = 0.25;
ThreadWidth = 2.0 * ThreadThick;

HoleWindage = 0.2;

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

Protrusion = 0.1;			// make holes end cleanly

//----------------------
// Dimensions

ID = 5.0;
OD = ID + 2*ThreadWidth;
Length = 5.0;
Sides = 8;

//----------------------
// 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 them!

ShowPegGrid();

  rotate(180/Sides) {
	difference() {
	  PolyCyl(OD,Length,8);
	  translate([0,0,-Protrusion])
		PolyCyl(ID,(Length + 2*Protrusion),8);
	}
  }
```
2012-04-24
Recommended Scissors

These Fiskars scissors [Update: they’ve moved to the Gardening section. Try there or there. ] seem to be intended for sewing & quilting, but they work just fine for snipping plastic filament, cutting tape, and severing hangnails…

Fiskars Softouch Scissors

The titanium nitride coating probably doesn’t add much value to the mix, but that’s what they had at JoAnne Fabric when I bought ’em.

Fiskars scissors tip detail

This detail of the tip shows why they’re so great for detail work: each blade ends in a two-way taper to a genuine cutting point. Of course, that means they’ll survive exactly zero falls to the shop’s concrete floor, but they’re fine while they last.

The trick is to sign up for JoAnne sale flyers, which regularly deliver “40% off any one item” discount coupons, then make a targeted shopping expedition. Those coupons account for the green self-healing cutting mat that’s in the background of so many pictures around here, too…

2011-03-06
Extended Sewing Machine Quilting Surface

Extended quilting surface

Mary has been quilting up a storm lately and wanted a larger surface to handle a bed-sized quilt. A table in the basement was big enough, but she wanted a larger flat surface around the sewing machine adjacent to the table.

I converted the typing return (*) from her upstairs desk into a table, then cut a piece of aluminum-clad 1-inch foam insulation board to fit. It’s 4 feet long, a convenient length to cut from the 4×8-foot insulation board, and slightly narrower than the typing return. Cutting it required a long X-Acto knife blade, but a really sharp utility knife would work as well.

Some stainless-steel tape finished off the edges. The tape itself is lethally sharp-edged, but it’s perfectly harmless if you do a good job of smoothing it against the foam board…

A pair of closed-cell rigid foam blocks held one end of the board at the proper height around the sewing machine, while a pair of cutoffs from the wood pile were just the right thickness & length to extend under the other end. It turns out that precise height isn’t nearly as vital as we expected; close enough is fine.

I cannibalized a pair of table-saw feed roller stands for this project; they had just the right height adjustment and shape to support the typing return and the foam board.

The end result aligns the surface of the sewing machine with both the top of the table and the surface of the foam board. The quilt slides easily over the whole affair and doesn’t bunch up like it did before. Success!

Foam support blocks

(*) A “typing return” is the little table that sticks out from a desk, upon which you put a typewriter, back in the day when typewriters ruled the land. Nowadays, she uses it for her sewing machine, which normally lives at her desk, because there’s no practical way to type at right angles to one’s desk.

That’s the sort of item you can’t do web searches for, because all the terms are so heavily overloaded. Give it a try; you’ll find one or two useful hits. There’s a difference between syntax and semantics; we’re not in the semantic web yet by long yardage.

2009-10-11