Friday, 3 May 2013

Sprocket cushion

This cushion is from the amazing tutorial at Cluck Cluck Sew.

The pattern comes for two sizes, but actually you can choose any size and any number of segments by making your own pattern.  You can either draw by hand, or follow my steps (outline at the bottom of this post) in Inkscape, a free vector graphics editor which is a very useful tool (in my opinion).

I made a couple of changes to the pattern.  One was to made the cushion thicker: I went for 5" finished depth.  The other changes were to add a concealed zipper (to make cover removal easier), and to create the final shaping by sewing between two covered buttons (not just one).  I also use a 1/4" seam allowance throughout (the original tutorial uses 1/2").

The zipped side panel

Although you'll still have to snip the buttons off to remove the pad, a zip makes the whole cover-changing process easier (no stitches to unpick).  I've not seen concealed zips on commercial cushions before (only in dressmaking) but I think it's a good thing in this pillow because I wouldn't want to spoil the look with a lapped zip.  Nevertheless, I've done one with a lapped zip before and it was okay.

Concealed zipper.  Behold the pattern matching: woo hoo!
To make inserting the cushion pad easy, ideally the zipper length should be half the circumference of the cushion.  For a 16" diameter cushion this is: 3.14 * 16" = 50.24" circumference, so a 25" zip would be nice.  The longest concealed zip I could find in the right colour was 22" so that had to do.

The cushion side bits consist of three parts.  Two are 3.25" x 23.5" and one is 5.5" x 27.74".  Where did this come from?  The two parts go either side of the zipper and need to be 5/2 + 0.25 + 0.5" = 3.25" wide by 22 - 1 + 2 + 2* 0.25 = 23.5" long.  The width is chosen to be half of the finished width, plus a 1/4" seam allowance on the outer edge and a 1/2" seam allowance at the zip edge.  The length is the nominal zipper length, minus 1" (the working part of the zip always seems a little shorter), plus 1" at either end to join the fabric pieces together at the zip ends. plus 1/4" seam allowance at each end.  The third fabric piece is 5 + 2*0.25 = 5.5" wide by 50.24 - 23 + 2*0.25  = 27.74" long.  This piece completes the circumference (what remains after the 23" length section with the zipper in), and has a width of 5", but we add a 0.25" seam allowance all the way around, hence the 2*0.25 parts we added to width and length.

The concealed zipper is inserted between the two narrow fabric pieces: centre the zipper along the long edge.  We've allowed 1/2" seam allowance to insert the zip; see The Coletterie for a tutorial on inserting this sort of zip.  Finish sewing the seam between the two fabric bits at either end of the zip, so you wind up with a 23.5" strip of fabric which is 5.5" wide and has a zip in the middle.

Join the zipped-piece to the third fabric piece using a 1/4" seam at along the short edges.  You should end up with a loop of fabric which is 5.5" wide and 50.24" around the circumference.  You can now continue making your cushion as described in the original tutorial.

The covered buttons

The cushion is given shape by stitching through the whole pad with a button on the front.  I used another smaller covered button on the back too, so that the stitches didn't pull through the fabric.  To strengthen the areas where the thread passes through, I used several layers of fusible medium weight interfacing (vilene).  I ironed lots of small (2cm square) scraps on in the centre of the back cushion piece.  On the front piece, I stabilised the centre by basting a small circle of cotton on the wrong size of the fabric where the spokes meet, adding scraps of fusible too for good measure.  The basting stitches come through to the front but will be hidden by the button.

Back of cushion

After I had put the cushion pad inside, I added the buttons as follows:
  1. Thread a straight upholstery or bookbinders' needle with a double thickness of button-thread (this stuff is thick!) and pull it well through the eye.  You'll end up with four thicknesses of thread passing through the pillow in one go.
  2. Start on the outside of the centre back, passing through the centre of the cushion and up through the front piece.  Leave the tail of the thread hanging out behind the cushion.
  3. Thread the front button onto the needle and then dive back through the cushion and come out at the back, where you started.
  4. Thread the back button onto the threads.  You can now snip the threads to remove your needle and tie the 8 threads tightly.  Knot them well and trim them short: the knot will disappear under the back button.

A circular cushion pad

None of the ready-made circular ones were to my taste (too small and flat), so I started with a 24" square feather pillow.  If I were sensible (and loved mess) then I'd open it up, empty the feathers somewhere for safekeeping and sew it into a 24" diameter circle before re-stuffing.  Instead, I just sewed over the cushion pad on the outside to knock the corners off.  I didn't even chop off the empty corners of fabric, I just folded them over as I inserted the cushion.  Okay, it's still a little square, but I saved filling my house with duck-down.

This tutorial is part of a series:

[Pattern making steps below the jump!]

Making a sprocket pattern in Inkscape

Firstly, decide your pillow diameter and number of segments; I think I went for 16" with 12 radial segments.

1.  Open Inkscape and draw any old circle using the circle tool.
2.  Click away from the circle, and select the black arrow tool.  Then click your circle to select it.  Some handles should appear and the toolbar should give you options to adjust W and H, the width and height of your circle (see image below).  Type the diameter of your pillow into the W and H boxes.  Make sure you've chosen the correct units (e.g. "in").

 3.  Your circle will transform to be the size of the cushion.  Probably this is much larger than an A4 sheet of paper, but not to worry for the moment.
4. We'll change the circle into just the segment we need for each spoke.  Select the circle tool again, and click back on your circle to select it.  The toolbar should bow allow you the options "Start" and "End", which define where the arc of your segment will start and end.  Ambiguous naming, I think.  For 12 spokes, you'll want 360/12 = 30 degrees per segment, so change "End:" to read 30.0, and leave "Start:" as 0.0.  For just 10 spokes, you'd do 360/10 = 36.0 etc.
5.  Your circle will have transformed into a segment.
6. Use the select tool (black arrow) to click the segment until the handles turn into rotating ones like those shown below:
7.  Drag the handles to rotate the segment so it fits on your page.  Next we'll be adding the 1/4" seam allowance.
8.  With the segment selected, do Path>"Object to Path".  This makes Inkscape treat the segment as a generic path rather than a bit of a circle.  Then copy the object and paste another one so you have two.
9.  You need to align these two copies.  Select the original one, hold down shift, then click on the copied segment; both will now be selected.  Next, do Object>"Align and Distribute..." to open the Alignment toolbox.    Choose alignments relative to "First selected", then click "Align relative to horizontal axis" (selected in the image below), and also "Align relative to vertical axis" (the button above it).  The copy will move to be directly over the original.
10.  Click away from both objects (in a blank bit of page) to de-select them and make all the handles disappear.

11.  We'll now set up Inkscape to add path outsets in units of 1/4", which helps us to add the seam allowance.  Inkscape needs the measurement of 1/4" (= 0.25") in px, and I note that 210 mm = 744.09 px (from the page size).  I calculate that 0.25 in * 25.4 mm/in * 744.09/210 px/mm = 22.5 px.  So 1/4" = 22.5 px.  Go to File>"Inkscape Preferences">Steps and type the value 22.5 in under "Inset/Outset by:".  Close the dialog box.

12.  Select one of the segments and do Path>Outset.  Magically it will grow by 1/4" all round!  Seam allowance added.
13.  Print your pattern.  It might be wise to add a label on it first.  Remember: cut out your pattern with paper scissors, NEVER your fabric shears or else you'll blunt them.  That will be sad (unless you know a man with workshop tools who will return them to you so sharp that they cut human flesh on sight, but that's still a bad outcome).


  1. This comment has been removed by the author.

  2. for some reason I show up as unknown, even when I log in - good info but I'm confused with the outset bit.

    0.25 in * 25.4 mm/in * 744.09/210 px/mm = 22.5 px does not work out right it comes out to 18,899.886 - how does that become 22.5px?

    no variation of those numbers gives me 22.5

    also my A4 page size is 210mm = 793.701px so I realise I need to change 744.09 for 793.701 but if the original sum is not coming out right for me, I have no chance of using my numbers

    1. If you are confused by the units I've written explicitly, ignore the units and just write down the sum with only the numbers: 0.25 x 25.4 x 744.09 / 210 = 22.5. According to my calculator, multiplying 0.25, 25.4 and 744.09 together and dividing by 210 does indeed give 22.5.

      With your A4 page size you'll do:
      0.25 x 25.4 x 793.701 / 210 = 24.0px

  3. This comment has been removed by the author.

  4. still won't say who I am when logged in as I show up as unknown...
    I think I know what it is. in the text the divided by 210 looks like it's saying 744.09 or 210 as in the px/mm. so that is where it is all going wrong.

    Thanks. was wondering why I was getting 18,000+ and not near your figure.

  5. still not working for me. I set my inset/outset to be 24.0000 px, duplicate my shape (simple square converted to a path) but my outset cut line is almost 1 inch outside not the 1/4 I expected - shame we can't attach pics would be easier to show ;) back to the drawing board for me then.....