Monday, December 22, 2014

Who'd a thunk? to get an accurate seam allowance

Spent a lazy afternoon on Sunday.  After a dynamic and rocking service at church in the morning, hubby and I treated ourselves to a lovely pedicure!  He still won't choose any colour and the girls at the nail salon tease him more and more!  We then went home and just vegged in front of the TV.  I had the first season of Hawaii Five-0 on the TV and since I have watched most of the episodes, was not quite paying attention.  My lap top in my lap kept the other part of my brain working.

Here's what I learned yesterday afternoon from Pinterest.

How to sew with an accurate 1/4" seam allowance.  

OK, I've been sewing with a 1/4" seam allowance forever!  I know how to do it right!  I know how to trick my machine and use my favourite, regular sewing machine foot instead of a patchwork foot to sew 1/4" seams.....don't I?

I started looking into this because I am writing the draft for my January WonderFil Newsletter and our focus thread this month is DecoBob.  DecoBob is an 80wt thread that is "perfect for piecing". And apparently you will get a much more accurate 1/4" seam allowance.  Well, before I started spouting, I thought I'd do a little research to add to what I already know about machines and 1/4" seam allowances.

Sewing machines use little metal teeth (feed dogs) to feed the fabric from the front of the machine to the back. As the fabric is fed through, the needle will go up and down through the fabric and make a stitch with thread.  If the feed dogs don't move the fabric, the needle will stitch in one place.

Instead of just one feed dog, there are often 3-7 sets of little metal teeth that work to feed the fabric. Some of these teeth are placed close together and on some machines, further apart.


Many 1/4" or patchwork feet are narrower than a normal or standard sewing foot to allow you to feed the fabric against the edge of the foot and get your 1/4" seam allowance.  


If the foot you use is narrow as you go over the feed dogs, the fabric won't be fed evenly and some sewers complain of the fabric pulling to one side as they sew.  Can you see that the foot and fabric are not covering the feed dogs completely?  I find that when I sew with a 1/4" foot, my fabric tends to drift to the left and I am always pulling my fabric to the right against the edge of the foot.  I solved this problem by using my open toe or satin stitch sewing foot and moving my needle to a position on the right, closer to the edge of the foot.


Many computerized machines will have a needle centre position.  When the machine is turned on, the needle will set itself to be in a centre position.  Use the features on your machine to move the needle closer  to the right edge of the foot.  My centre needle position is at 3.5mm.  The full width of the stitches are 7mm.

I did some testing.  I cut a number of strips of fabric 2" wide.  I sewed 3 strips together with a needle postion of 6mm (what I have always used for my 1/4" seam allowance).  I lined my fabric against the edge of my foot. I pressed these seams very gently to make sure I didn't stretch anything. You will have to look closely, but you can definitely see that the sample sewn with a 6mm needle position does not quite measure 5" (I moved the ruler over 1/2" for more visibility).  The centre strip is just shy of the 1" mark.     

The sample sewn with the 6.5mm needle position, measures much closer to that desired 5" amount. The centre strip is a much more accurate 1".  

So, its only a few threads you say.  But imagine a few threads at every seam and suddenly a 6" block with 6 pieces of fabric doesn't measure the desired 6"!  So, going forward, I'm going to sew with a 6.5mm needle position on my machine.

Now the next challenge is sewing a straight line.  One of the Pinterest posts suggested masking tape and another one suggested Post-It Notes.  I think I may prefer the masking tape as a physical guide because it will stay in place longer than the Post-It Notes.  Below are some of the great ideas I found this weekend that set me on the right track.

I challenge everyone to CHECK YOUR 1/4" SEAM ALLOWANCE!

1 comment:

  1. Great information, Allison! I am definitely checking my ¼" seam on my machines. Didn't think about the feed dog impact when stitching.