This Wednesday I would like to discuss a very important lesson I learned this week. As the title eluded a 1/4” is not necessarily a 1/4”. I assumed that my sewing machine was an accurate 1/4” seam from the needle to the outside of the presser foot. I found out that, in fact, was dead wrong. You see it was off ever so slightly. How did I figure this out. Well when I went to cut the strips of fabric for the Supernova quilt into blocks I noticed that mine were only 9-3/4” wide.
Where did the other 3/4” go?! So I measured and re-measured and found out that I was just a teeny bit off, but that teeny bit compounded and added up quickly. Needless to say my blocks are now 9-3/4” by 9-3/4” which means that my quilt will be ultimately smaller and I will have to adjust the triangle blocks as well. (they need to be trimmed down 1/4”)
Notice how it is a 1/4” to the inside of the stitching. That is where the problem lies.
The finished blocks should be 2” wide. Notice how mine (because of the discrepancy on both sides) are now 1-7/8” wide. Two eights equals a 1/4” and with three of these type of seams in the five strip block we have found our missing 3/4”
How do we avoid this? Great question! You MUST measure from the outside (left side) of your needle to 1/4”. If it isn’t the end of your presser foot then you will want to mark it with masking or painters tape to make sure you get the perfect seam allowance every time. I recommend taking the presser foot off for this exercise. Also make sure that your tape is straight from the starting point so you are heading down the runway straight so to speak. (I’ve used ribbon here because I am out of painters tape at the moment)
Once you have marked the sewing machine you will want to sew a test strip on a scrap of fabric to make sure it is accurate. If it isn’t keep measuring and testing until it is. It will, as I have recently learned save you a lot of math and frustration on future projects.
Hopefully this will save you from the puzzlement that I endured. So as I said, a 1/4” is not a 1/4” is not a 1/4”.
Have a fantastic evening! See you Sunday!