Accurate 1/4 inch seams

[Diane O.]

I have been having problems with my blocks not coming out the right size. They aren't off by much, but it is driving me crazy. I have tried Margo's test of cutting strips and sewing them together then measuring the finished size.
The first set it was off by 1/8 inch almost the entire length. The second set, was better. It was accurate in the middle, but at the ends it was off by an 1/8 inch.
My cutting was accruate, I was careful with my pressing, and made sure that there weren't any tucks at the seam. I was careful to line up my fabric with the mark I made on the tape for 1/4 inch from the needle and to make sure my fabric didn't drift at the beginning or end of the seam, so I'm not sure why it isn't the right size.

Any suggestions on what else I could try to get accurate seams?? I want to make sure I get my seams accurate before I start sewing my blocks on a new quilt.

Thanks for any suggestions

Diane in Colorado Springs

[Diane O.]

When the size is too small consistently along the length of the sample, it could have to do with the 'turn of cloth', that is how thick the cloth is and how much is used to fold back on itself. This can also be affected by your sewing thread, a thicker thread will take up more fabric in the 'turn' than a finer thread.

On last year's BOM I found that to have accurate 1" squares I needed to stitch a 'bare' 1/4" seam, rather than a 'good' 1/4" seam - what side of the line are you stitching on? It can make a difference at each seam, which multiplys by your seams.

I found that I needed to decide between whether I went with making sure that my 1" squares were exact and my seams were slightly fudged to be a bare 1/4"; or my seams were a perfect 1/4" and my 1" squares were slightly small - I decided that the front being accurate was more important than having perfect seams, especially as I was not always sure that my cutting was totally and utterly 100% accurate.

I hope this ramble helps
Rosemary.

[Diane O.]

Thank you for those thoughts Rosemary.

I'm using Masterpiece thread, so it isn't a thick thread.
I will try using a scant 1/4 inch and see if that helps.

I have a 1/4 inch foot with the guide on my machine, and I did notice while I was sewing my test strips, that it was lined up exactly with the mark I made on the tape. On my next test, I will not have the fabric butted against the guide so tight, and see if that helps.

I have started a Kaleidoscope quilt (not Rickys Kaleidoscope quilts, but Marti Michelle Kaleidoscopes) so with 8 pieces per block coming together in the center, it is important to have them turn out accurate.

Diane in Colorado Springs

[Jill B.]

Hi Diane,

Thank you for this question as I too can have this problem and like you follow all the steps and try so hard to get it right.

I to will use a scant 1/4 and see how that works for me, and thanks heaps for the reply as it all helps.

Also I have told to make sure your rulers measure right as apparently sometimes the cheap ones you buy can be a bit out, I found this on one of my rulers.

Regards Jill Australia

[Jill B.]

I find on my Bernina that even when I sew so that I can just see the line on the plate in front of the quarter inch foot, I still have a tendency for being on the small side. I move the needle just one place to the right, even in the space of the quarter inch foot and single hole throat plate, and it is much improved.

I think just that tiny movement makes up for the fabric/thread thickness Rosemary is talking about.

I was going to ask the technician to look at the needle alignment when the machine goes in for its service but I'm so used to it now I can compensate. :roll:

[Myra U.]

Marcia Hohn (the Quilter's Cache) has a great tutorial about 1/4" seams in which she says that she always uses a scant 1/4"; in other words, she seams at about 3/16" due to the width the fabric takes up when you press the seam, whether it's open or to one side. She has had a web site for a very long time and she offers her patterns on it free of charge. The tutorials are all written out, but they are very clear and useful. Her web site is http://www.quilterscache.com In about the middle of the page as you scroll down, there is a box that says "Where do you want to go today?" and it has links to all she has to offer. I was having the same problem you are and that tutorial helped me a lot. Good luck!!

[Myra U.]

If you are using the 1/4 inch foot with guide, measure the distance from your needle to the guide. Mine was set to a generous 1/4 inch! Just tighten the screw at the back of the foot, it will move the guide closer to the edge of the foot.

Jean in Windsor, ON

[Myra U.]

If you don't prewash your fabric, it is possible that it could shrink slightly if you're pressing with steam. This may not apply to your problem, but I did hear about it happening recently to someone else.

[Judy B.]

It also makes a difference as to how "square" you are sitting in front of your machine. If you are not directly in front of the machine, you'll be looking at your guide from an angle and that will throw things off. (Same goes for cutting things out)

[Judy B.]

Joanne Middleton ( Patchwork School House WAy) had tutorial DVDs where she teaches perscision piecing...

She says most inaccurate 1/4 inch seams result when we chain piece ... the act of getting the next set we take our eyes/ mind off the last little bit of the seam which then tends to wander off.

She says this is acctually the most important part of the seam and we should acctually guide the fabric with a stilletto til we are off the fabric... stop and then get the next set of patchwork... making sure we start the next patch accurately.

I found her 7 set DVD classes invaluable for improving or a least highlighting what I do wrong.... KNOWING often leads to improvement and correcting the problems.


Anna

[Judy B.]

I do a scant 1/4" seam, and try to concentrate on that last bit of seam as it is easy to wander off a bit. Also use cutting rulers from the same manufacturer as they can vary a bit I believe.

[Judy B.]

I have started using Superior Bottom line for piecing and now the "normal" threads seem so clunky and make a bigger edge when the pieces are pressed. Amazing what a difference it makes. Cheryl

[Myra U.]

cjbeg,
I agree with you! The Superior Threads Bottom Line has helped me tremendously in more than just 1/4" seams. I LOVE their thread. LOVE it!!!

[Margo C.]

Here is a link to the seam allowance "TEST" that I offer on my Webshots page. Remember..... that unless your pieces are cut correctly in the first place, your seam allowance can't make everything fit exactly. What is important is the size of your PIECES after you have sewn the seams!

http://good-times.webshots.com/album/569415726bHNKHF

[Margo C.]

I had the same problem. I put a I think they are called throat plate with the 1/4 inch mark on it and my seams were accurate. I make sure all the edges are straight before I sew the pieces together. now my blocks measure correctly.