Is a quarter inch seam allowance important? Do I really need a special foot in order to obtain a perfect quarter inch? How do I obtain the perfect quarter inch?
Purchase a special quarter inch piecing foot at your sewing machine dealer. Each brand of sewing machine will have a quarter inch piecing foot available to fit their specific models. A generic quarter inch foot known as a "Patchwork" foot is also available and might be available at your sewing machine dealer or local quilt shop. Or a quarter inch foot for one specific brand may in fact fit another brand of machine so check around and see which one works best for your machine.
Go to your sewing machine dealer and ask if you can try their quarter inch piecing foot. One style of quarter inch foot might meet your needs more than another. I prefer the "generic" patchwork piecing foot over the quarter inch foot that was supplied with my brand name computerized sewing machine.
Your quarter inch should be very accurate when making your own blocks but even more accurate if you are working on a group quilt that others will be working on also.
For the perfect quarter inch
Cut your fabric pieces as accurately as possible. Sometimes simply the width of a marking pencil is enough to cause inaccuracy. When using acrylic tools include the line in measuring. For example if you are cutting a two inch strip -- the previous cut edge of the fabric should include the two inch line on the ruler in your strip.
If you need to use a presser foot you already have and it isn't quite accurate here are some things you might try.
Machine setting -- If your machine has settings for different needle positions, simply set your needle to the left or right so your stitching line is exactly a scant 1/4" from the edge of the presser foot. Program this into your machine memory so you can touch a button every time you turn on your machine. If your machine doesn't have a memory, write your special piecing setting on an index card or sticky note and keep it near your machine.
Make a raised area to guide the fabric -- Place the quarter inch line of a small ruler under the presser foot with 1/4" showing at the right of the needle. Turn the hand wheel on the machine until the needle touches the 1/4" mark on the ruler. Move the ruler back and forth as necessary until the 1/4" mark is exactly below the point of the needle. Cut a piece of masking tape about two inches long and place it on the bed of the sewing machine butted up to the right of the ruler. Place additional layers of tape to build up a thickness so you have a raised area to guide the fabric accurately. The same could be done with a stack of sticky notes.
An alternate to masking tape and sticky notes would mole foam -- a foot care product available in the pharmacy. Cut a piece about 1/4" wide and two inches long. Peel the protective paper and stick the mole foam on the machine bed next to the ruler.
Careful pressing is also important to accurate piecing. If the pieces are not pressed carefully some inaccuracy can occur. A lot of patterns call for a scant quarter inch simply because a tiny amount of the seam allowance is taken up in the fold.
A quarter inch seam allowance is very important to the success of your quilt piecing. So a little time spent getting a correct seam allowance will be well worth it in the long run.
Making Bias Tubes For Applique Vines
If you wish to make appliqué vines that curve, you will want to use bias strips. If your vine is to be continuous around the border you will need a longer length than if you are making a small stem for an individual flower.
Bias strips are cut on the diagonal of fabric and when made into bias tubing can be appliquéd to a quilt block or border. If you wish the stem to curve you must use bias as it will work around curves without puckering.
With bias press bars, you simply cut the bias, stitch it on the machine and insert the bias press bar into the tube and use it to assist you as you press.
Bias press bars are very useful tool to have and can be obtained at the local quilt shop or online quilt store for around six dollars. They come in a set of five press bars and are of different widths. My set has 1/8", 3/16", 1/4", 3/8", and 1/2" widths available. They are 12" long and made of heat resistant nylon. Metal bias bars are available but will get hot when pressed so be careful not to burn your fingers.
Bias tubing is machine stitched but NOT turned. The bias press bars are inserted into the bias tubing for pressing. As you press you turn the seam allowance to the top of the press bar and press. Slide the press bar the length of the bias tube and continue until completely pressed. Remove press bar and give the bias an additional steam press.
Decide the width you need for your finished bias tube or vine. Trim and straighten the cut edges of your fabric. Use your 45 degree angle on your acrylic ruler and cut off a large triangle. You now have a bias cut. Cut additional strips the width needed by lining your acrylic ruler with your first bias cut. Bias strips may be seamed together for a longer length. A 1 1/2" strip width is sufficient for any of the bias bar widths listed above.
For a 1/4" (finished) bias tube I usually cut my strips 1" wide and then piece as necessary. Press seams open when piecing the strips. Once you have strips the length you like, fold strips in half lengthwise WRONG sides together and machine stitch with the folded edge toward the right. For making 1/4" bias tube you simply use your quarter inch foot as a guide for the folded edge. If you are making wider bias tubes simply use the markings on the throat plate to guide your stitching.
Do not turn the tube. Trim the seam allowance to 1/8". Insert rounded end of bias bar into the tube. Roll the seam allowance to the center of the flat side of the press bar. Press in one direction with a hot iron. Remove press bar and press tube with hot iron to hold crease. If you wish you may dampen with a little water or spray sizing to help hold the crease.
When placing the bias tubing on your appliqué background simply place with the seam allowance on the underside. After it is stitched the seam does not show and the bias stem actually looks slightly raised because of the thickness of the seam allowance on the underside.
Some patterns will have a placement diagram for the vine and other appliqué pieces. Simply place the placement diagram on a light box and your quilt border on top. Draw the placement line with a removable marking pencil.
If you do not have a placement diagram, cut a piece of freezer paper or shelf paper the length of your border. Fold it in half and half again until you have fold lines the distance of your curves. Draw a curved line on one segment, and copy it on all the other segments. This is your placement diagram. Draw the vine placement line on the quilt border.
Use acid free glue stick or other basting glue to temporarily adhere the bias vine to the border. You may also hand baste if you wish. Be careful not to stretch the bias as you are gluing or basting. The bias will curve around a corner the outside edge will "give" a little.
Hand or machine stitch both sides of the bias using thread the color of the vine or a monofilament thread.