Skip the Grading to Copy a Bias-Cut Tank Top Pattern

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Learn how to trace a bias-cut tank top pattern from your bodice block so you skip grading and start with a fit you already trust.

Using Your Bodice Block To Copy a Bias-Cut Tank Top Pattern

Andrea holding a pattern for a tank top and a matching block pattern design
Blocks just work.

One of my favorite reasons to sew with a bodice block is simple. Once the block fits, I do not have to start fitting from zero every time I see a new pattern I like. This tutorial shows how I used my bodice block to copy the design of a bias-cut tank top, using Burda 6774 as my reference pattern, without doing any grading between sizes.

Block, Not Sloper: Why I Work This Way

In patternmaking language, a block or sloper is a close-fitting base pattern used as the starting point for other designs. A classic sloper is drafted without seam allowances and without design ease. A block, the way I use it at SewToFit, includes seam allowances and the amount of ease I personally want to wear. It is already proven on my body, so it becomes my reference for everything else.

That is why I prefer the word block in my teaching. My block is a real garment shape I know will work, not just a theoretical template. When I compare any commercial pattern to that block, I can see in one glance what will feel comfortable and what will not.

What We Are Making: A Bias-Cut Tank From a Fitted Block

The pattern I used in the video is Burda 6774, which includes a sleeveless bias-cut top. The style lines are very close to my fitted bodice block. It is basically:

  • A sleeveless version of my block
  • Narrower shoulders and straps
  • A lower neckline front and back
  • Cut on the bias for a softer drape

Instead of picking a size and grading between several sizes, I placed the pattern directly on top of my bodice block and treated the block as the “truth.” The goal was to copy the design details of the tank top onto a pattern that already matches my body.

Tools I Used On The Table

You do not need drafting software for this. On camera I used:

Use the tools you trust, but keep the lines accurate. Pen tips and fat markers take up space, so remember that every line has thickness.

Step 1: Align The Front Pattern To Your Block

I start at the center front and the shoulder. I place the commercial pattern over my block, matching the center front line to the center front of my block. Then I slide the pattern up or down until the shoulder seam matches.

In this case, both the pattern and my block had seam allowances included, which keeps the comparison straightforward. Once the shoulders were aligned I could see that the pattern’s armhole was lower under the arm than mine and that the shoulder was cut in more toward the neck. The neckline shape was also different.

At this point I decide what I am willing to live with. I was happy with a slightly narrower shoulder, and I had a mark for where my bra strap sits, so I could make sure the strap would be covered.

Step 2: Raise The Underarm For Your Own Coverage

Under the arm, I prefer a higher fit than many commercial patterns. On the pattern tissue, the underarm seam allowance dropped below the level of my block. Since I know my block already clears my bra and gives me the coverage I want, I followed the block at the underarm.

This is the kind of change you can see instantly when you have a block. The decision was simple: I raised the underarm on the new pattern to match my bodice block, then re-drew the armhole curve with the French curve.

Step 3: Trace The Neckline And Armhole With A Tracing Wheel

I used a tracing wheel to copy the neckline and armhole shape from the bias tank pattern onto my paper, through the block. The pattern line I wanted was marked in a contrasting color, so you could see the distinction between:

  • The block’s armhole and neckline
  • The commercial pattern’s lower neckline and reshaped armhole

I followed the design of the tank wherever I agreed with it, then blended back to my block at the side seam and underarm to maintain fit. Once the tracing marks were on the paper, I removed the tissue and cleaned the dotted line into a smooth, continuous curve.

Step 4: Set The Bias Grainline

Because this tank is cut on the bias, the grainline is not straight up and down. After tracing the outline, I drew in a strong grainline at 45 degrees across the front. I extended that line all the way across the pattern so I can see it at both top and bottom edges.

That bias grainline is labeled clearly on the final pattern piece. I noted “Bias GL” and ignored my earlier rough line that I had drawn incorrectly. When you work on camera it is more important that students understand the correction than that the paper looks perfect.

Step 5: Place, Move, And True The Dart

The original pattern had its own side seam dart position. My block has a dart that is already set for my bust point, so I rely on my dart, not theirs. I rotated the dart on my block to match the side seam location I wanted, then transferred that dart onto the new tank pattern.

To true the dart, I folded the dart legs as if the fabric were sewn, matched the side seam edges, and used the tracing wheel to mark the new cutting line across the folded dart. When I opened the paper, I had a clean, continuous side seam that will sew without a jog at the dart apex.

Step 6: Draft The Back To Match The Front

For the back, I repeated the process. I aligned the center back of the pattern with my back bodice block and matched the shoulder. This pattern has a lower scoop in the back neckline, so I checked how low it would fall on my body. I decided the scoop was acceptable, then made sure to raise the back underarm to my own block level for coverage.

Again, I gave myself a little extra room at the hip by extending slightly beyond my block. Bias garments tend to skim the body, and I wanted the back to hang clean instead of clinging too tightly. Then I used the front side seam as a guide so the back side seam length and curve would match.

Step 7: Label, Cut, And Save Your New Bias Tank Block

Once both pieces were drawn, I labeled them clearly:

  • Pattern name or number (for example, “Burda 6774 inspired bias tank”)
  • Front or back
  • Size or “Andrea’s block size”
  • Bias grainline arrow and notation
  • Date

I trimmed away the heavy marker line so the final pattern reflects the true size, then set this pattern aside as my new bias tank block. From now on, when I want a woven bias tank in silk or other drapey fabrics, I can pull this block instead of starting over from the commercial tissue.

Where To Learn The Full Block-Based Fitting Process

This lesson is one small piece of the larger block-based fitting system I teach in SewToFit. The real power comes from first creating and fitting your bodice block, then learning how to compare that block to any commercial pattern before you cut fabric.

If you want help building your own bodice block and learning how to use it on real patterns, explore my classes and resources in my membership here: SewToFit.com. Inside my community I walk you through this process step by step on live projects, so you can apply the same method to tops, dresses, and more for your personal projects and body.

For another related read, look for my post on building your first bodice block as a fitting tool, where I explain measurements, ease, and why I prefer a block over simple size charts.

Categories: : Designing, pattern fittimg

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