Blog Hop

Back to School Blog Hop – Corner Triangles


It’s my turn to talk about corner triangles as part of the Back to School Blog Hop. Sam Hunter from Hunter’s Design Studio is hosting a month (and a bit) long feast of tutorials on many of the techniques we commonly use in our sewing and quilting.

If you have missed any of the great tips and tricks then you can still visit:

or mark in your calendar the remaining posts from:

Lately, I have been making many quilts and blocks with corner triangles. It can be a simple process if you follow some simple rules. The most important rule is aim for accuracy.

Corner Triangles

Corner triangles are used in many block patterns as an easy way to make an angled piece rather than cut templates. It starts with 2 pieces.  While these 2 pieces do not have to be the same size, the angle of both corners have to be identical. i.e the 2 pieces when placed together should have 2 sides flush.

Corner Triangles_1

To mark or not to mark

Use a visual guide to sew a diagonal line. There are three common methods.

  • Draw a line from corner to corner.
  • Use the markings on your machine plate or table.
  • Use notions like the Clearly Perfect Angles. (One of my personal favourites).


Follow these simple rules to achieve a perfect corner triangle every time.

  1. Starch well to maintain the shape of the pieces.
  2. Cut your pieces with accuracy. It is really important that the 2 pieces when placed together perfectly fit along the top and side edges.
  3. Mark your diagonal line with accuracy.
  4. Pin your pieces in place so there is no slippage.

Corner Triangles_2

Make sure the needle starts and ends exactly on each corner.

  • Use a scrap piece of fabric to lead onto the intended piece. This stops the fabric being sucked into the stitch plate.
  • Use a machine foot that you can clearly see where the needle will be placed.
  • If possible, manually lower the needle into the starting position of each piece.
  • Slowly start and finish each piece.

Sew 1 stitch width on inside of line.

  • The reason why we do this is to compensation for the fold in the fabric when you press it back.

Corner Triangles_3

5. Trim back your corner leaving a 1/4″ seam allowance. This reduces bulk.


Corner Triangles_4


6. Press not iron your corner. Aggressive ironing can distort the triangle. The bias has been taken care of by stitching on the diagonal line of the piece ( or bias ) before cutting. This gives it some body but distortion can still occur.

Why it is important to start and stop exactly on the corner ?

  • Corner triangle pieces often intersect with other pieces and therefore the measurement on top and side must be accurate. If you have missed the corners on start and finish, there may be an overhang of fabric which affects the unfinished size of the piece. Never trim the excess as it will change the measurement of ‘x’ and will not fit with adjoining pieces or blocks.  Always get out the unpicker and start again. It is worth it in the end.

Corner Triangles_5

If you can master these simple rules then making flying geese or any angled block will become a breeze.

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