How To Make A Half-Square Triangle Flannel Rag Quilt With The Batting Buddy

Published November 2025

Join Tammy as she shows you how to create a half-square triangle rag quilt using the Batting Buddy Template from Creative Grids! She walks you through how to use the Batting Buddy in a different way to create a unique flannel quilt. Using a quilt as you go method, this Half-Square Triangle Flannel Rag Quilt lets you simply stitch, snip, and enjoy. Made with 10" squares, it comes together quickly and is filled with handmade love.

In this video, you'll learn:

• How a long seam guide with center marks removes the guesswork from half-square triangles.
• A way to quilt a perfect X on every block without marking a single line.
• How the Batting Buddy template centers your batting with exactly an inch all around.
• Which seams have to be sewn all the way to the edge if you plan to bind — and why.
• How to miter a corner when your binding uses a half-inch seam allowance instead of a quarter.

Check the links for everything you need.

Introduction

This is the third project built around the Batting Buddy template, and it starts from 10″ flannel squares. Precut 10″ squares are the easy route, but there’s nothing special about them — if you have a flannel stash, cutting your own 10″ squares works exactly the same way.

Flannel deserves a word of warning before you begin: it’s thicker than quilting cotton, it shifts more, and it has a mind of its own at the corners. Most of the techniques below exist specifically to manage that.

Making the Half-Square Triangles

The usual method — draw a diagonal line, then find a quarter inch on either side of it — is exactly the fiddly part. A seam guide removes it.

1. Pair two complementary 10″ squares and turn one wrong side up.
2. Lay a seam guide diagonally across it. You need a long one here: a 15″ guide reaches corner to corner on a 10″ square, where a 9″ guide will not.
3. Look for the small center marks at each end of the guide, and set those exactly on the points of the square. That alignment is what guarantees the guide sits truly on the diagonal.
4. Mark down both sides of the guide with a Frixion pen, rotating your mat rather than the fabric to draw the second line.
5. Layer the two squares right sides together and pin. Heavier pins earn their keep in flannel — fine patchwork pins bend.
6. Stitch directly on both drawn lines.

Those two lines are sewing lines, not cutting lines — the guide has taken an exact half inch out of the middle, which is a quarter inch on either side of the true diagonal. To separate the units, put the quarter-inch mark of a ruler right on one seam line and cut, and you’re cutting precisely down the center.

Press these seams open. With flannel, distributing bulk away from the seams matters more than it does with quilting cotton, and an open seam simply makes more sense here.

Marking, Trimming, and Cutting Batting

The Batting Buddy template comes in two parts — an outer frame and a center piece — and both get used.

1. Lay the outer frame, which measures exactly 9.5″, over your pieced square.
2. Mark the four corners through the template with a Frixion pen, pressing firmly enough that the marks stay clearly visible. These become your start and stop points when you sew the rows, so they need to survive handling.
3. Trim all the way around the frame to bring the block to exactly 9.5″. A rotating mat makes this quick — turn the mat, not the block.
4. Switch to the center piece for the batting. Stack your batting scraps — eight layers is quite manageable — and cut around the template with a 60 mm rotary cutter. The larger blade cuts deeper than a 45 mm and gets through far more layers at once.

Leftover batting from previous quilting projects is ideal for this; it never needs to be one continuous piece.

Building and Quilting the Block

Each block is two half-square triangle squares with batting sandwiched between them, quilted as you assemble it.

1. Lay the unmarked square wrong side up, with its seam running from top left to lower right.
2. Set the template frame on it, drop a piece of batting into the opening, and lift the template away. The batting lands perfectly centered, with exactly one inch of flannel showing all around.
3. Place the marked square on top — but turn it so its seam runs in the opposite direction to the one underneath.
4. Pin at your corner marks. Those corners will try to walk apart as you sew; this is flannel.
5. Stitch in the ditch from corner to corner, shortening your stitch length slightly (around 2.15) and gently easing the fabric apart with your hands as you go so the ditch stays visible.

Starting a seam right on a corner point is something many machines dislike. A starter strip solves it: sew onto a scrap first, then feed the block in as though you were chain piecing, and give the strip a gentle pull if the machine needs help getting going. Clip it off afterward.

A quilted X with nothing marked. Because the two squares were laid with their seams crossing, flipping the block over reveals a ditch running the other diagonal. Sew that one the same way and you have a perfectly quilted X — without having drawn a single line on the block. The seams themselves did the marking.

That trick only works where there’s a seam to follow. On solid blocks with no piecing, mark the diagonals with a water-soluble pencil — they come in white, pink, and blue, and the marks wash out at the end along with everything else.

A chalk marker will also make a line, but be careful with chalk on this project. It brushes away easily, and if you’re stacking finished flannel blocks in a pile before carrying them to the machine, the chalk transfers onto everything it touches and disappears from where you wanted it.

Assembling the Rows for a Bound Edge

Here is where a bound rag quilt parts company with a traditional one. Blocks are joined with a generous one inch seam allowance, and on most machines the outermost marking on the stitch plate is exactly that — 8/8 of an inch.

The outside edges must be sewn closed. On a normal rag quilt, leaving the outer seams open is fine — they just get clipped. If you’re binding, those edges have to be joined all the way to the end, or you’ll have a gap running around the whole perimeter with nothing solid to stitch your binding to.

In practice that means treating your first and last rows differently from the ones in the middle:

1. On the first row, start at the very top raw edge, backstitch, sew down to your corner mark, and backstitch there.
2. On the last row, start at the corner mark, backstitch, then sew all the way off the edge and backstitch again.
3. Everything in between is joined mark to mark as usual, leaving the centers open.
4. Pin generously — you’re going through four layers of flannel and two of batting, which is a lot to hold together.
5. Once the top is assembled, run a quarter-inch seam all the way around the outside edge, laying the seams open and sewing straight across them. This flattens the perimeter and gets it ready for binding.

Those unsewn centers aren’t an oversight — they get trimmed out later to remove bulk where four blocks meet.

Adding the Binding

The binding is cut wide and sewn on with a half-inch seam, which is what gives it that substantial look against the ragged seams.

1. Cut 4″ strips, join them with straight seams, press those seams open, and fold the whole strip in half lengthwise.
2. Leave a generous tail and begin sewing with a half-inch seam allowance. It doesn’t matter where on the quilt you start.
3. At each corner, stop a half inch from the edge rather than the usual quarter — your stopping distance always matches your seam allowance. Backstitch there; backstitching is what holds this heavy binding in place.
4. Fold the binding up so its edge runs even with the next side of the quilt, then bring it back down on itself with the folded edge level with the top. Resume sewing at a half inch, starting right at the edge.
5. Press the binding away from the quilt all the way around. This makes turning it far easier.
6. Turn the binding to the back and hold it with clips.

One detail decides whether the final stitching works: the binding on the back must completely cover the stitch line from when you attached it. You’ll be top stitching from the front, right in the ditch alongside the binding, and that stitch lands very close to the original seam. If the back binding falls short of it, your stitching misses and the binding isn’t caught.

To top stitch, push the binding over with your index finger to expose the ditch and sew right next to it, pivoting with the needle down at the corners. Use thread that matches your binding and the stitches disappear — and on the front, flannel relaxes back over the seam so they never show at all.

Clipping and Washing

The binding goes on before any clipping, simply because handling a fully ragged quilt while trying to attach binding is unpleasant.

1. Make a first cut about a half inch in from the binding, through both layers, so the seam allowances can stand up together.
2. Trim out the corner bulk in the middle where four blocks meet — those centers you deliberately left unsewn. Removing them makes the intersections noticeably cleaner.
3. Clip the seam allowances roughly every half inch, cutting both layers at once. A quarter inch also works if you prefer a denser fringe. The spacing doesn’t need to be precise.

Spring-loaded rag quilt scissors make this far less tiring than regular shears — they open themselves, so you’re only closing your hand. Rag quilting scissors with heavy sharp blades work well too, being built for multiple flannel layers.

Then comes the part that actually makes a rag quilt:

1. Wash it on a heavy cycle.
2. Take it straight outside and shake it hard — that removes a surprising amount of loose thread before it ever reaches the dryer.
3. Dry it with a couple of bath towels and several dryer balls, which bounce around and fluff the seams open.
4. Stop after ten or fifteen minutes and clean your lint trap and dryer vent. It will be completely full. Then finish drying.
5. Shake it outside once more when it comes out. The birds will happily take the threads for nesting.

The binding is what makes this version worth the extra planning — it gives a rag quilt a proper finished border, heavy enough to survive washing after washing without fraying away. Just remember that the decision to bind has to be made at the start, because it changes how those first and last rows get sewn.

Browse our Creative Grids rulers and seam guides, pick up sturdy pins and rag quilting scissors from Gypsy Quilter, and explore the rest of our notions to get started.