Use your sewing machine to make your own clothes or alter garments to better suit your needs. With some skill, alter a pattern while making a new shirt, or alter a shirt that is already made. Make a shirt larger in the midriff or stomach area by sewing gussets into the sides of the shirt. Ease a tight fit through the arm area by adding gussets in the underarm seam. (Gussets are strips of fabric, either rectangular or triangular in shape, sewn into the seam area of a garment.) To alter a tight-fitting garment, make gussets from fabric matching the shirt.
Open the underarm seam of your shirt with a seam ripper. Begin right under the arm area where the sleeve and shirt side meets. Cut stitches with the seam ripper to open the seam 2 1/2 inches down the side of the shirt, then cut stitches to open the seam 2 1/2 inches in the sleeve seam, creating a 5 inch long opening under the arm of your shirt. Repeat on the other side of the shirt.
Cut two 3 inch square pieces of fabric for gussets. A shirt with a long tail may have enough extra fabric to allow for cutting the gussets from the bottom of the shirt tail. Cut gussets on the bias to provide extra give during arm movements.
With right sides together, pin one corner of a gusset to the beginning of the opening in one of the sleeves. Pin the opposite corner to the beginning of the opening on the shirt side. Pin the gusset to the underarm opening, creating a diamond shape under the arm of the shirt. Repeat on the other side of the shirt.
Hand baste the gusset in place. With a hand-sewing needle and thread, baste with long stitches, allowing a 1/2 inch seam allowance. Repeat for the gusset on the other side of the shirt.
Machine stitch a gusset into place. Use back stitching to secure stitches. Back stitches are made by sewing forward several stitches and then reversing and sewing backward a few stitches.
Trim the seam allowance. Zigzag the seam allowance to add extra strength to the seam. Press the shirt.
Open the shirt side seam with a seam ripper. Begin at the bottom of the shirt and open the seam to within 3 inches of the underarm seam.
Put the shirt with opened sides on the shirt owner and measure the distance needed for the shirt sides to meet comfortably. Measure from the edge of the fabric on one side of the opening to the edge of the fabric on the other side of the opening.
Cut a triangular piece of fabric, 2 inches wider than the desired width of the insert. Cut the fabric with the bottom of the triangle on the straight grain of the fabric.
With right sides together, place the triangle in the opening in the side of the shirt. Pin the point of the triangle at the top of the seam opening. Pin each side from point to bottom to prevent stretching and bunching of fabric.
Hand baste the insert into place. Machine sew. Trim the seam. Zigzag the seam for added strength. Press the seam.
Add gussets while sewing new garments to provide ease of movement in sport shirts or clothing that will be worn during vigorous physical activity. Sport shirts often have underarm gussets of contrasting colour.
Plan thoughtfully before altering a shirt. Certain fabrics do not lend themselves as easily to alteration. Silk, satin and fabrics that ravel easily require special care and should be altered by only the most experienced tailors. When opening a seam with a seam ripper, be careful not to cut the fabric. Just cut the stitches to loosen the threads so the seam will come apart.