Saturday, January 30, 2016

Zip A Bag: Responses to Comments II

Hello friends!

It looks like Zip A Bag is turning out to be more interactive than I'd imagined! You're asking questions and leaving comments that jump-start discussions, and I consolidate my responses into a single QnA post in between chunks of tutorial posts. I'm happy to do it, so keep those comments and questions coming! 

1  What kind of machine do you use?
I cannot remember the exact context of this question, but the accompanying words implied something like, "your bags look so professionally stitched. Do you have a special machine?"

Short answer = No, I don't.
My sewing machine is a Pfaff Classicstyle 1525. It's nothing fancy. It is completely manual and has something like only 8 or 10 stitches, total. However, it is a real workhorse, specifically because it can handle multiple layers of thick fabric, which is why I bought it over the other fancier electronic machines that embroider your family crest while you're mixing a batch of cookie dough somewhere else in the house.
Someday I want to own an industrial lockstitch machine. It certainly will be more fun to sew bags with - if nothing else, because its longer arm will make it easier to maneuver bulkier bag parts. But I don't have the space in the house for it right now.

I don't think a fancier sewing machine helps you make better bags, though. When I was in my teens and early twenties, I made bags in worse fabrics than these (i.e. like outdoor sports bags and huge padded cases for musical instruments) on the family treadle machine (also a Pfaff). I think what's more important is how you get your machine (and tools) to work for you, and how much you practice you get at making bags.

2  How do you sew through all those layers?
While nothing like what I subjected my old treadle to in the old days,  I will admit that I still put my modern Pfaff through bag hell. Multiple layers and thick fabrics and batting and sponge and foam and stuff like that are the status quo. Yes, there has been wrestling. Yes, I've broken needles. Yes, I've impaled my own fingers. Yes, there have been times when I've made myself give up, walk away, and come back the next day because I needed a break. There are limits, after all, to stitching commercial-design materials and configurations on a home sewing machine. I share my struggles so you know that putting together a bag that aims to look like you might see it in a shop window is hard work.

That said, here are some things I've found helpful in working with these thick layers.

(i) Needles
I seldom use universal needles in bagmaking (unless I'm sewing a feeble lining of quilting cotton or homedec fabric over a negligible-weight sew-in stabilizer). For the robust outer layers of a bag, I replace the universal with a Jeans/Denim Needle (good for sewing canvas and such) or a Leather Needle (good for vinyl and other such sticky fabrics) and leave it in for the whole bag-making process. Both those needles have thicker and stronger shafts than universals, can accommodate thicker thread (i.e. less snapping) and can topstitch. 

Another tip: I've noticed that some fabrics with coarse weave and thick fibers show up topstitching horribly, no matter how gorgeous your tension is. Duck cloth is an example - my topstitching often is wretchedly crooked and looks like I've pulled the thread too tight. I know it's not the tension because the minute I lay, say, a piece of quilting cotton on top of that duck cloth and topstitch those two together, the stitches are once again stunningly beautiful. In cases in which I need the topstitching to be on the bare duck cloth (or other coarse weave heavyweight fabric), I use a denim needle and use smaller stitches. It pierces the fibers better and the smaller stitches, while still pushed this way and that by the weave, look less crooked overall, than longer stitches.

(ii) Walking Foot
My Pfaff machine has an integrated walking foot (that's the black thing behind the presser foot).

If your machine has a walking foot, use it whenever you sew bags. There will be less sliding and slipping with the thicker layers with the walking foot engaged.

(iii) Pins, basting and clips
I do not pin along seams because seams need to be eased as one sews, to avoid puckers and other hideous mistakes. Instead, I pin reference points, i.e. points that need to be matched with other points. I also pin particular points that need to align with print, and parts of zipper tapes that need to align on both sides of an opening, and accent fabric layers that need to lay flat without shearing. 

Otherwise, I baste (or tack). I hand-baste concave curves to convex curves, and bindings that need to be stitched with identical allowance on WS and RS, and anything that requires easing to fit something else. I machine-baste strap ends onto bag bodies, and multiple layers to each other, stitching within their SA regions so these are hidden away in the final seams and don't need to be unpicked. This way, I can sew over them along the actual stitching lines without worrying about hitting pins or clips.

Sometimes I use those cute little Clover wonder clips for fabrics that aren't hole-friendly and can't be pinned or basted. They are useful for holding layers together as you are assembling them for sewing. But they wouldn't be my first choice, because you can't sew over them, and they get stuck at the side of the presser foot and still have to be moved as you ease the layers together, and sometimes leave indentation marks on puffy materials (like neoprene).

(iv) Speed
I speed-stitch things like straps and straight seams and basting stabilizers to outer fabric layers. But I go slow when I am assembling layers, and going over bumpy lumpy seams that have straps inserted into them. There are times when I turn the crank and tighten the upper tension by hand, going a stitch at a time, to be sure the needle goes all the way through the layers, catches the bobbin thread, and pulls it up without skipping.

(v) Hand-stitching
There are also times when I will deliberately hand-stitch a seam, especially one that is in a visually-obvious location on the finished project. Thread tension, even when adjusted to perfection, will still sabotage you when you jump-the-hump, as is often the case around bag openings which have straps inserted on opposite sides. Sometimes, I will stop machine-stitching a couple of inches away from bulky seams and leave long trailing threads, which I'll then thread through an upholstery needle, to finish the seam by hand. Some of those bulky layers are so tough to stitch that I need pliers to pull the needle through them - so it's no wonder that the sewing machine fails.

3  How do you draft a rounded rectangular base?
Here is a rounded rectangular base. 

To do this, I first decide how large a rectangle I want. 

Let's say that I want it to be 8" x 6".
So I draw that on paper:
Then I round off a corner by tracing around a circular thing. A smaller circular thing gives a sharper, more acute corner, and makes the overall shape more like the original rectangle.

A larger circular thing gives a flatter corner and makes the overall shape more like an oval.

Then I fold that rectangle into quarters and cut the corner out in four layers, to get four identical corners.

4 How do you draft an oval?
Start with the size of the oval you want - we call these dimensions the axes. Let's say that we want an oval that is H high and L wide.

Fold your pattern paper into quarters, 

draw those axes along the fold lines,

and draw a curve between the axes. Cut out, unfold and examine.

Adjust by trial, error and preference until you get the oval shape you want.

5 And how do you make the body cylinder fit that oval/rounded rectangular base? Is there a Math formula?
I'm sure there is. For a circle, for instance, it's pi (or 22/7) times the diameter . So a 14" circle has a 44" circumference. But for all other shapes, I just use a measuring tape.

Make the base. Do not add seam allowance.

Measure the perimeter of the base. This will be the actual stitching line.

Draw a rectangle for the body cylinder. Match the width of the body cylinder to the perimeter of the base. And make the height whatever you want your bag's height to be. These lines are the actual stitching lines.

Now add your SA. 

When you sew up the side seams and attach the base to the bottom opening of the cylinder, you can be sure that your stitching lines will match exactly, because that's how you drafted them.

6  How do you attach a circular (or any shaped-) base to the bottom of a cylinder?
Four rules:

Ensure the stitching lines match. See the notes to question 5. If the stitching lines (not the actual edges of the fabric, which include the widths of the SA, which throw all your dimensions off) match, your base will fit exactly into the cylinder's opening without fear of puckering.

Make quarter marks on the base and again on the cylinder's bottom edge. Match these up when you sew, to ensure that you are distributing the cylinder fabric evenly around the base.

Snip the SA of the cylinder's bottom opening. When you are attaching a vertical wall (like the cylinder) to a flat base, the wall's SA prevents the stitching lines of both pieces from touching. Snipping the SA lets the bottom edge of the cylinder spread flat on the base so the stitching lines can get close to each other. And when the stitching lines match up, the cylinder will fit perfectly with the base without gathers or puckers.

Sew with the cylinder on top and the base below. The base is a flat piece while the cylinder is a bulky lump of gathers and folds that need to be manipulated (we call this process "easing") around the curve of the base as you sew.

7  Can you provide dimensions/templates/patterns?
So many people have asked for them that I might, yes.

There are 25(? I can't remember) bags and pouches in this series. And they are almost all prototypes, meaning that they are the first samples from the designs, and I sewed them up as I designed them, without a lot of tweaking. I'm thinking that at the end of the series, I could corral my templates (assuming I haven't tossed them out), trace out the ones that have non-easy-geometrical shapes, and measure the dimensions of the others which are simple rectangles and circles, compile them as a collection of templates in a single pdf file and put this file in my pattern store for you to purchase. 

Please note that they will ONLY be templates, NOT patterns. This means that there will be NO instructions, only dimensions and measurements and template shapes. You can buy the file, print out the templates, and return to this Zip A Bag series for the free instructions to make the bags and pouches themselves. They will not be as detailed as a typical ikatbag pattern because I don't have the time to write 25 patterns, but I'll still put in a fair bit of work to ensure that the corners match up and the seams align, and so on. Plus you'll then have the option to avoid drafting the templates and eyeballing the measurements yourself. 

Would this be something you might be interested in? If so, let me know in the comments.

Thursday, January 28, 2016

Zip A Bag Chapter 10: Diamond-Front Backpack

A very long post today.

But I am very excited to share today's bag with you, because there are TWO zippers in it, with TWO different functions!

Zipper #1 opens and closes the bag itself - and it is exactly the same fully-open installation as we learned in the previous post's pouch (say that fast 10 times).

Zipper #2 separates the carrying strap into two narrower straps, 

allowing the bag to be carried cross-body,

on one shoulder,

or both.

Before we look at the zipper installation, let's talk about the structure of this bag, so you'll know how to draft and cut the necessary fabric pieces for it.

First of all, it's a bucket-style bag. This means you'll need 
  • a base - mine was a rounded rectangle. 
  • a rectangle for the body, which is sewn into a cylinder. The height of the rectangle is the height of the bag. The width of the rectangle is the perimeter of the base. 

Repeat these two shapes in the lining layer. I pieced two fabrics together in the body rectangle of mine - the coordinating grey upper band to face the zipper, and the contrasting yellow lower band. I also added two pockets for functionality: a large patch pocket on the front face,

and a zippered welt pocket on the back face.

For the outer bag layer, I used a light grey vinyl and Jessica Jones' Navy Loop Timewarp barkcloth by Cloud9 Fabrics. That same vinyl is used for the straps.

Finally, I used two zippers for the bag - one for the strap (20") and a separating zipper for the top opening (the zipper's length is a little over half the width of the body rectangle.) A third zipper was used for the internal welt pocket.

STAGE 1: Visualize
I cannot say enough about the importance of visualizing in sewing.

I suspect lots of folks don't enjoy visualizing. They'd much prefer the thrill of going "blind" into someone else's pattern, dutifully following instructions and then being elated when they successfully arrive at the finished product. I can totally understand - it's extremely exciting, and a bit like magic, going from Step 1 to Step 2 to Step 3 to . . . Step 96, and suddenly, they've got An Awesome Bag or An Amazing Dress.

However, I also suspect that there are those among us who have been intimidated by a pattern that seemed difficult, and which they therefore passed over, because they couldn't imagine how they in particular could get from Step 1 to Step 96 and produce That Bag or That Dress. That Bag or That Dress, they reasoned, seemed way beyond what they'd ever made, way beyond their skill level, way beyond anything in the realm of the familiar.


If they would but visualize, they could make anything.
Because while the end product may not be familiar, visualizing helps you to get from Here to There along pathways that are. 

Okay, let's conduct an experiment.

This bag

is the same as this pouch

but with straps.

You don't believe me.

I shall attempt to prove it to you by visualizing.

First, visualize this pouch much taller.

Now imagine its base turned 90 degrees, so that its longer axis is perpendicular to the zipper.

Now imagine that fabric tab extended into a carrying strap

that inserts into the base seam of the bag.

And finally, imagine the front part of the pouch folded downward so the zipper pull almost touches the base seam.


I rest my case.

STAGE 2: Install the main zipper
Remember that this zipper is a fully-open-style zipper, which you can now install in your sleep.


The green arrows show the head end of the zipper. In the pouch, we curved the head ends of the zipper tape into the SA (blue circle), one side at a time.,

and then brought them together when we sewed the side seam.

In today's bag, we're going to curve both sides of the zipper tape at the same time, with their heads together at the midline of the body. 
In the photo below, there is a long, straight strip of vinyl grey that will form the top edge of the bag opening. I bent it to fit into the photo frame, but in subsequent photos, you'll see it straightened out. In the middle of the strip, curve/fold the heads of the zipper tape into the SA, as shown. The heads themselves will not touch - there is a space of about 1/2" between them, to prevent bunching at the meeting point when the zipper is closed. Baste the zipper tapes to one long edge of the vinyl strip.

Now with RS together, baste the other edge of the vinyl strip to the top edge of the fabric body.

Flip the vinyl strip up and edge-stitch on its RS to secure in place.

We'll next need to face that zipper with the lining fabric. 

This is the big-picture sequence:
  1. sew the side seams of the outer body to create a cylinder. Do the same for the lining body. Then
  2. sew the lining and outer cylinders together around their top openings, facing the zipper in the process. 

Side notes:
  • See those two upside-down zipper tapes? When you face them with the lining fabric, their SA will get tucked into the seam and the zipper coils will flip upward. 
  • See those metal stops? They are not cool. Normally, if I'd had a long enough zipper, I'd have tucked the head ends of the zipper tape into the seam, including the bits with the metal stops. Unfortunately, this zipper was barely long enough for the opening, so I had to use every last mm of it and let the stops peek out. Boo. Hiss.

Returning now to the construction sequence: 

(i)   Make an outer cylinder.

(ii)  Make a lining cylinder.

(iii) Turn one cylinder WS out and the other RS out. 

(iv) Insert the latter into the former so their RS are in contact. 

(v) Stitch their upper circumferences together, sandwiching the zipper tape between them, and facing the zipper in the process. Because you sewed the side seams of each cylinder separately, their ugly raw SA will now be hidden away between the cylinder layers. Yay.

(vi) Turn the entire double-layered cylinder RS out and edge-stitch around the opening. 

STAGE 3: Attach the base
Turn the half-finished bag WS out again. Working first with the outer layer:

(i)  Attach the outer base to the bottom opening of the outer cylinder, being careful to push the lining cylinder out of the way. I added piping to mine. 

 (ii)  Insert two buckle anchors into the base seam, for the straps to lock into.

(iii)  Sew the lining base to the lining cylinder, pushing the outer fabric layers out of the way. Leave a gap for turning the entire bag RS out later. 
You will now have two individual completed bags, connected only around their main opening.

(iv)  Turn the entire bag RS out through the seam gap and hand-stitch the gap shut. 

STAGE 4: Make the strap
Warning: the how-tos in this stage are going to look a bit skimpy, only because we'll be revising this strap again in detail in the next post.

We're essentially going to sew a strap around each side of the zipper tape, and then when the zipper unzips, you'll get two separate straps. 

So take two strips of fabric 

sandwich one side of the zipper tape between their RS, 

and sew.

Fold the fabric strips RS out and finish their other long edges by tucking in their SA to the WS and edge-stitching. Then repeat with two new fabric strips on the other side of the zipper tape. If that made no sense to you at all, fear not - the next tutorial will bring you through those steps in photos.

Anyway, the finished outcome will be one narrow strap on either side of the zipper coils, as shown. 

I am more interested today to bring your attention to the bit where the zipper pull rests at the end of the coils.

The straps join only partway along their length, so that even when zipped together, their ends are separated into two base anchors 

for its backpack strap configuration.

and when completely unzipped, separates fully into two individual straps.

The head ends of the zipper tape must therefore be curved into the SA of the fabric straps the same way that the main (dark blue) zipper's curved into the SA of the bag opening.

STAGE 5: Attach the strap
Zip up the bag opening and fold it into a diamond shape as shown. The strap will attach to the tail end of the zipper through a collar.

The collar is just a cylinder which fits snugly over the end of the strap. We'll sew the collar to the strap first, then attach the other end of the collar to the bag.

Make a tube and fit it WS out over the tail end of the zipper. I pulled my collar low enough for the stitches to avoid the chunky retainer box. Sew through all layers, then flip the collar RS out over the end of the strap.

Now insert the other end over the tail end of the bag zipper. Tuck in the collar's SA to its WS,

and edge-stitch to secure in place. 

This is what the finished collar looks like.

Here's an additional feature I added - an oversize pull tab

with a magnetic snap.

If you want to include this in your bag, you will need to install the magnetic snap while you can still freely manipulate just the outer layer without getting tangled in the lining layer i.e. before sewing the lining base to the lining cylinder in Stage 3.

Otherwise, here's another variation I found on Pinterest - it uses a snap hook whose anchor is sewn into the base seam. 

Finally, here is the finished bag.

I punched holes in the free ends of the straps for adjusting their lengths through the fixed buckles anchored to the base. 

So there - a diamond-front backpack which is really just your oversized fully-open pouch with a strap.

Not as difficult as it looked, right?