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For a half-square triangle (HST), press the seam allowance to one side, place the Bloc Loc ruler with its logo on the opposite, low side, and seat the groove over the seam. Trim two sides, rotate the unit and ruler together, align to the desired size, and trim the last two sides. Start with an oversized unit so there is fabric to remove.
How to trim a half-square triangle with a Bloc Loc ruler
The groove registers the ruler against the seam allowance. For an HST, the seam allowance creates a raised “high” side; the opposite side is the “low” side. The logo orientation matters because it positions the groove correctly against the seam.
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- Premium Quilting Ruler - Bloc Loc rulers for quilting make squaring up & trimming a breeze!
- Offers Accurate Measuring - With easy-to-read, bold number markings.
- Non-Slip Grip - Holds the fabric in place, keeping it from sliding & rocking while you quilt.
- For Beginners & Experts Alike - A practical triangular ruler for everyone’s quilting needs
- Made of Durable Materials - This clear acrylic ruler will last for years!
- Make the HST oversized. Piece the unit larger than the size you want to finish with. The extra fabric gives you room to square the block accurately.
- Press the seam to one side. Identify the high side, where the seam allowance lies, and the low side, without the seam allowance.
- Position the ruler. Set it on the HST with the Bloc Loc logo on the low side. Slide the ruler’s channel over the diagonal seam until it seats against it.
- Align and trim two sides. Adjust the ruler markings to the size you are trimming to, leaving enough excess fabric for the next cuts. Hold the ruler securely and cut along two adjacent edges.
- Rotate for the remaining cuts. Hold the ruler at the two corners beside the channel, push it down, then rotate the ruler and HST together. Align the ruler to the desired finished size and trim the final two sides.
AllPeopleQuilt illustrates this HST placement and trim sequence in its Bloc Loc ruler tutorial. Follow the instructions supplied with your particular ruler if its shape or trimming method differs.
Choosing an HST ruler size
Bloc Loc’s HST rulers are offered in multiple sizes, and the maker says they trim in 1/8-inch increments. Check the size range for the specific ruler before choosing it; a larger HST ruler may work for a smaller unit if the groove can seat on the seam and the markings let you align the unit correctly. This guidance applies to HST rulers, not automatically to every Bloc Loc ruler family.
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- QUILT RULERS – Make trimming & squaring half-square triangles fast & consistent with our square ruler for quilting. Set 1 includes 6 sizes from 1.5" to 6.5", giving you half square quilting rulers for block building ease.
- PRECISION MEASURING – Bold, high-contrast measurements printed on each quilt square ruler ensure edges aligned. The quilters ruler helps you identify size at a glance, keeping seams even & blocks uniform.
- NON-SLIP GRIP – The engineered grooves on our half square triangle rulers for quilting and sewing lock onto the seam to stop sliding & rocking while cutting. Fabric stays in place with this quilting square ruler. No more uneven trimming or shifting.
- ALL SKILL LEVELS – Available in various sizes for quilt rulers and templates that cover everything from small patchwork to large quilt blocks. Quilt rulers for quilting for beginner & experienced quilters, giving the same dependable control in any project scale.
- CLEAR ACRYLIC – Our sewing square ruler is made from sturdy acrylic that maintains transparency for years of cutting, trimming, & travel between sewing rooms. Your acrylic ruler for cutting fabric that resists repeated use.
Choose for the HST’s intended finished size and the amount of trimming flexibility you need. The manufacturer’s HST ruler collection lists the available models and links to model-specific instructions and cutting information.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Other Bloc Loc ruler types work differently
Bloc Loc makes shape-specific rulers for units including flying geese, half-rectangle triangles, strip sets, Drunkard’s Path, triangle-in-a-square, kite-in-a-square, diamond-in-a-triangle, log cabin, pineapple, and kaleidoscope. The shape, dimensions, and trimming workflow vary, so an HST procedure should not be assumed to apply to another model. The official ruler catalog links to product instructions, charts, and tutorials; its video index includes demonstrations and tips on trimming, measurements, rotary cutting, and pressing seams.
Flying geese
For the flying-geese method described by AllPeopleQuilt, the unit is made from two squares and one rectangle. The ruler’s two grooves align with the seams, and trimming is done with care to retain the triangle points. Bloc Loc’s flying-geese rulers are listed by finished unit size, while the physical ruler is 1/2 inch larger. Check the individual product page and instructions to confirm the sizing convention for the ruler you have.
Drunkard’s Path and other specialty shapes
AllPeopleQuilt describes Bloc Loc’s Drunkard’s Path set as including separate cutting and trimming pieces, with additional pieces for elongated shapes. Other families, such as triangle-in-a-square, kite-in-a-square, and diamond-in-a-triangle, have their own finished-size conventions. Consult the instructions for the exact model rather than relying on its name or nominal size alone.
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- Great for Sewing, Quilting and other Crafting Projects"
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Rank #4
- have a groove to lock the ruler into place on your seam
- make the tough job of squaring up easy and fast
- Easy to read numbers and grid lines in 1/2" increments
- Acrylic
What to check before selecting a ruler
- Unit shape: Match the ruler to the unit you are making; these are not all-purpose rulers.
- Finished dimensions and increments: Confirm the intended unit size and the range the model accommodates.
- Size labeling: Check whether the stated measurement refers to the finished unit or the ruler’s physical dimensions. The maker specifically lists flying-geese rulers as 1/2 inch larger than their finished-size labels.
- Set contents: Determine whether the project requires one ruler or a multi-piece set, particularly for specialty units.
- Model instructions: Use the product’s instructions and charts for its exact alignment and cutting sequence.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
