Trimming Points for On-Point Settings

Setting blocks on point opens up a lot of design options.  Five years ago I wrote a post about on-point settings, including how to cut side and corner setting triangles and tips for sewing with them.  Click here to go read about that.  Since then I have designed and sewn several more patterns using on-point settings and I have fine-tuned my process.

Everything in that original post is still valid, but I have added point trimming to my process.  The more consistent end result makes the extra little bit of time and effort worth it to me.  

Sample on-point setting using 4" finished blocks in place of blocks.

Why do I trim the points? Proper trimming will make the edges being sewn together perfectly matched in size, so you can pin them exactly where they need to be, from one end of the seam to the other, to avoid accidentally stretching a bias edge past where it's supposed to be.

You can download and print the template I use in this tutorial.  Make sure you print actual size.  When printed correctly, the 1" square should measure 1" on all sides.

Once printed, I tape the template to the underside of a rotary cutting ruler, oriented as shown below, with the blunt tips of the template flush with the sides of the ruler.  The size of the ruler doesn't matter.  Which corner of the ruler I choose also does not matter.  I'm not going to be measuring anything with the template.  I'm just using the ruler's solid edges as a guide for my rotary cutter when I trim the points.

Is your template ready?  I'll wait.  

Also, you may like to read my older post I linked above to review how to cut side and corner triangles to end up with straight of grain on the edges of your quilt.

Now, let's take a look at how to trim points in different situations.  In some cases we'll need the templates. In others just a ruler will do.  

Trimming side triangles

Adding the side triangle to a row is simple.  Line up the square corner with the corner of the block or row.  The tip of the triangle will stick out beyond the block/row.

The side of the triangle that will be sewn is a bias edge, and there is a risk it will get stretched. If you trim the tip off, so the side of the triangle is the same height as the side of the block/row to which you plan to sew it, you know exactly where to pin the triangle in place, precisely where it needs to be to avoid stretching as you sew.

In the example below I measured and trimmed 4 1/2" from the bottom of the triangles, to match the 4 1/2" side of the square.

You can see below how the trimmed point matches up perfectly with the square.

Do the same thing for a triangle on the opposite side.  

Side setting triangles sewn to both sides of the square

My example uses just one square, but adding triangles to either end of a row of blocks would work the same way.

Trimming Corner Triangles when lining up with side triangles

As you can see in the next two photos, the tips of the corner triangle will extend past the side triangles.

Please note that for all the remaining pictures I photographed the parts on my wool cutting mat instead of my cutting mat to reduce clutter in the image and keep the focus on the relevant parts of the image .  Of course you should cut on your cutting mat!  

Position the corner triangle over the row as you would sew it, right sides together (see previous photo).  Slide the corner triangle up off the row, taking care to not rotate it and leaving it right side down.  

Position the template as shown below, so one blunt tip of the template is flush with the long side of the side triangle, and the long side of the template is flush with the top of the row.  This orients the template properly.

Without turning the template, reposition it over the corner triangle as shown below, with the long sides flush with the long side of the tiangle, and one short side flush with the short side.  Trim the tip of the triangle flush with the template

Without turning the template or the corner triangle, reposition it, again matching the sides of the template with the sides of the triangle, and trim the point flush with the ruler.

Reposition the corner triangle over the block row, right sides together.  The angles at the tips should match the angles at the ends pf the block row exactly.  Pin them in place and add additional pins every 2" to 3" to keep things in place to minimize accidental stretching as you sew.

Trimming Corner Triangles - when adding to the end of a row

When a diagonal row ends at one of the corners of the quilt, you can add the corner triangle directly to the end of the row.  Again, the triangle points will extend past the sides sides of the last block in the row.

You can trim the points even with the sides of the block.  The key is to trim both points by the same amount, ensuring the 90 degree top point remains centered.  

Divide the size of the block by two.  In my example, the block is 4 1/2", so the measurement I need is 2 1/4".  This measurement is where the top point of the triangle should fall.  Let's call it the midpoint.

You can see below how to position the ruler so the midpoint measurement lines up with the top of the triangle.  Make sure the long side of the triangle is lined up with a horizontal line on the ruler, to ensure your cuts will be perpendicular to the triangle base.  Trim the point that extends past the ruler.

To trim the second point, reposition the ruler to measure a distance equal to the size of the block. In my example, that's 4 1/2".  Measure from the previously trimmed point, and keep the base of the triangle level with a horizontal line on the ruler.  

Trim the point that extends past the ruler.

The blunt trimmed points should now line up perfectly with the sides of the blocks.

Trimming when sewing rows together 

Trim as when adding a corner triangle to a row, matching the trimmer to the angles on one row/section and moving it to the point to be trimmed on the other row/section.

Lay out sections or rows.

Position sections and/or rows right sides together as for sewing.

Slide away the top row/section without turning it and position the trimming template on the bottom row/section to determine the correct orientation, matching the angle on the template with the angle on the bottom row/section.

Without turning the template, position it over the top row/section, matching the sides of the template with the sides of the row/section, and trim away the point.

Repeat at the other end of the row/section.

Slide the top row/section back over the bottom/row/section, matching the trimmed points and angles.  Also take care to match seams as needed along the seam.

With careful thought  and planning you could trim all the points before starting to assemble the quilt, but I prefer to trim as I go.  This lets me check the orientation of the trimmer at each step to make sure I'm trimming each tip the correct way.  For example, the two side setting triangles on opposite ends of the same row need different points trimmed.  Trimming as I go lets me check I'm trimmming the correct point one for each end.

One caution about the size of setting triangles

Maybe caution is too strong a word.  Just be aware that the math and geometry of setting triangles rarely work out to lovely perfect 1/8" increments that are easily measured and cut with our rotary cutting tools.  The sizes are usually rounded up to the next 1/8" for ease of measuring and cutting.  (You can download this reference sheet for guidance on figuring out sizes.)

Because of the rounding, the seam allowance around the perimeter of the quilt may be a little larger than 1/4".  This isn't a big deal, unless you want any points on the edge of the quilt to cozy up perfectly to a border or binding.  In such a case, you may want to trim the seam allowance down to a pefect 1/4" before you add the border or binding.

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That's it!  I hope you'll find this useful.  Please share your own tips and tricks in the comments.  

If you ask a question in the comments please understand that if your comments are anonymous or are set to "no-reply blogger", I have no way of contacting you directly.  You'll need to check back here for an answer.

Happy quilting,

Joanne

Enjoy 10% off these patterns with on-point settings in my Etsy Shop now through November 15th, 2025.  Use the coupon code ONPOINT at checkout or use this shop link.

Row 1: Shimmering Tiles, Fabulous Phlox, Field of Leaves
Row 2: Glacial, Modern Lace, Party Crackers
Row 3: Sparks, Starlight Plaid, On the Fence
Row 4: Fundy Skies, Triple Sunset, I Spy Lanterns