Accurate 1/4 inch seams

[Myra U.]

ladyrags,
I discovered this on my own several years ago. I was making a log cabin heart miniature wall hanging. Everything I did came out wrong. I was so D__N frustrated! I stopped and walked away for a while. When I came back, I looked carefully at the blocks on the log cabin. Every one had the same problem: I veered off to the right at the end of the seam. That part, of course is where we join to the next block. If both of them are off, big discrepancy. I corrected this and like magic!, the wall hanging went together perfectly and, easily. More importantly, I corrected a problem I was having with piecing. The source you quoted is right: the end IS the most important part of the seam. Good tips here, people! Thanks, I was also reminded of some things in making the perfect 1/4 inch seam.

[Myra U.]

before i cut the fabric, i starch iron it stiff, so when i cut it is accurate as it can be, then i iron it again, dont use pins but stellito (splg?).
it takes more time but it worth it, i do use the scant 1/4", i put (what you put on the bottom of chairs sort of white velt with sticky side to it) those strips just before the foot, so you have sort of a spore to the fabric.
i hope it will help

[Myra U.]

Harriet Hargraves suggest 60wt /3 ply thread WHICH IS THIN but terribly strong. ( See her newest books QUILTERS ACADEMY 1: FRESHMAN YEAR. )

I find I need a really good fabric guide to prevent my seam allowance from shifting. I have used all the methods listed above but it usually turns out to be how I feed my fabric into the machine. If you do not start off at the exact spot you need to maintain the 1/4 (scant 1/4 ) inch your seam allowance does not remain true.

[Myra U.]

Thanks for the info on 1/4 inch seams Margo!

[pigtailpat]

If you are working with a non-computerized sewing machine, the best combination is the perkins ruler and a magnetic seam guide - both of which cost peanuts.

The perkins ruler has an accurate 1/4 seam on it, and there is a small hole. You take the ruler, put it on your machine's bed, drop the needle into the hole (no thread in needle), then lower your presser foot right on top of the ruler, and make it straight.

Next, you take a magnetic seam guide and drop it down on your bed right next to the where the ruler is layer, or, a little ahead of the foot slightly more in to get a scant seam. Once your seam guide is positioned, lift your presser foot, life up the ruler, thread your needle and you should be good to go.

This is a technique for the older, non-computerized machines. There should be no magnetic anything on the bed of a computerized machine. For a computerized machine, you can still use the perkins ruler, except tape post-pad next to the ruler and build it up nice and firm so your fabric doesn't have a chance to move.

The perkins ruler has served me very well on my vintage machines. It is such a big help, and the lady who invented it is some brain.

Pat

[Jan K.]

Hi everyone!
Thread thickness, cutting, and seam width ALL account for variances in the seam widths. Many good tips have been provided!

Here is my test BEFORE EVERY PROJECT:
1. Cut 1-1/2" strips of fabric (about 4-5" long). Make sure they are uniform & straight.
2. Sew with your "normal" seam, sewing 3 pieces side-by side.
3. Press the seams open, or to the side - which ever method you will be using in your project.
4. DO NOT measure the seam width itself - measure the WIDTH of the unit across the 3 pieces - this is actually what matters, right?
5. If the sample is too small, your seam is likely 1-2 thread widths too WIDE.
5b. If the sample is too big, your seam is likely 1-2 thread widths too NARROW.
6. Try the test again with fresh fabric, either moving the needle slightly right or left, or lining up in a different place according to your presser foot.
7. The ultra-fine threads such as Bottom Line and Masterpiece, Aurifil and others DO provide a finer seam - however, evaluate the use of the project, and the amount of quilting you plan for the total strength of the thread in the project. For instance, if I am making a wall-hanging or art piece, it won't take a lot of laundering, wear-and-tear. Fine threads will work well. If I plan to do a lot of micro-quilting, the stitching through all layers will support the seams. However, if I plan moderate quilting (resulting in a softer, more pliable quilt), I need a stronger thread in the seams so it will hold up to everyday use and laundering.

FINAL comment - some sewing machines do not permit you to move the needle in fine increments. The feed-dogs may not like to feed the fabrics well when you are sewing an extremely narrow scant 1/4" seam. TRY THIS TECHNIQUE: When cutting, do not line up the raw edge between the cross-hairs of the ruler as you cut, but INCLUDE the PRINTED LINE as part of the cut. (Set the ruler on top of the fabric, allowing the printed line to set OVER the edge of the fabric.) The printed line will provide approximately the width of the thread in the seam, and you may have more consistent success!

Jan Krentz, Author, Designer, Instructor - http://www.jankrentz.com

[Kathryn S.]

Jan, thank for telling us about your method of "including the line" when cutting out, if we want to use a regular weight thread or a full quarter inch seam allowance. That makes so much sense! I have lately been doing the seam allowance test on every project trying to get it right before I start sewing the quilt. So if I cut a hair larger and use a slightly larger thread, that may just even out with a perfect measurement on the sewn piece.
PS I'm a big fan of your Lone Star quilts- you came to our guild in Simi Valley and it was a thrill to see them up close!
Kathy

[Jan K.]

Thanks for your comment, Kathy! Yes, I enjoyed comingto your guild!

The rulers out there on the market - there is one brand with thick extruded lines on the bottom. Many quilters LOVE this ruler because it minimizes slippage. However, those thick lines mean they are not as accurate as the rulers with the thinner lines. Just think - we ARE talking about thread thickness, and how it can make a big difference!

ANOTHER TIP:

Pay attention if you are using a presser foot with a flange on the right side. Many of us think: "I paid good money for this presser foot - and it is the SILVER BULLET that will give me a perfect seam!" Yet, many quilters press too hard against that flange (a loose separate piece of metal) in their gusto to sew quickly. The flange flexes, and the fabric may climb right up between the foot's edge and the flange itself..... or the fabric buckles, and the seam allowance is no more accurate than it was previously!

When using fine thread, your seam allowance will be more like a true 1/4". When using a standard dressmaking weight, it will be more like a scant (one thread narrower) 1/4".

I really like the Celine Perkins Perfect Piecing seam guide. I also have a similar tool, designed by me and tested by my Lone Star students. It has scant 1/4, 3/8, and 1/2" holes - plus an overlapped series of angles to use when marking your tips and sides of star points for Y seams.

Happy Stitching! Jan

[Jo H.]

Jan, thank you for such a helpful post. Thank you too for mentioning your tool. I just read about it and love that it has all of the different angles included on it! I must have it!

[Marion D.]

I was in a class with Jan Krentz. she had accurately cut some 1 1/2 inch strips. We set our guide up, sew a pair together, and then pressed and measured how big it was afterward. If it wasn't exactly right, we moved the guide (or the needle, whatever) and sewed another pair and tested.

[Kathryn S.]

I can remember when I got my new machine with the little flange on the quarter-inch foot. yes, I jammed the fabric up against the flange, couldn't see where the edge of the flange was (bought a new light to take care of that), messed with needle position. Then I bought a new foot and took off the flange- the edge of the foot was rounded. Then bought a new see through foot with Square edges on the right, and that's helping me a lot.

All those teeny 1 inch squares on the 2009 and 2011 BOM taught me to be very careful! I still have not yet attempted a Lone Star quilt, but it's on my to do list. Plenty of starch and measuring will be necessary, I think.

My latest quilt is 3 inch blocks, 14 across and down. The quilt top actually measured 42.5 inches, just what it was supposed to! I did a happy dance!

Kathy

[Kathryn S.]

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)

Oh, good point Judy! Thanks for this tip!

[Kathryn S.]

I am confused. I am reading this series of posts after seeing Tommy Romano's video on the 10 Commandments of precision piecing. He used a clear red tool to check with the needle down in the 1/4 inch hole on the tool, which puts the right side of the red tool where the fabric should end. Then you put something like moleskin or postits where the fabric should butt up against it.

He said that when you cut with a ruler you don't put the cloth under the line but next to the line, or it will add up to too big a piece, which would add up over the whole quilt. Do these ideas conflict with what Jan Krentz said? And if so there must be a reason. I am going to need to practice these techniques before the next quilt I do. And to get my piecing accurate. Will have to read this over and watch some of Sally Collins videos here. Jan

[Nancy R.]

Jan - You just need to try different methods to see what works for you. In Tony's instructions, he has you make a full 1/4" seam allowance, but has you measure just up to the line. This means that his seam allowance is slightly wider than a scant 1/4", but his strips are cut out slightly narrower than if you put the fabric under the line. You could also use a scant 1/4" and cut with the fabric under the line. The end result is the same. There are many other ways to approach getting the same result. I suggest trying everything you hear about and see which works best for you. And you'll want to test and adjust things depending on the fabric you are using since the thickness of your fabric can affect your end result (so you might need to use a slightly narrower seam for a commercial cotton than for a cotton batik).

Nancy

[Nancy R.]

Ooh. Nancy that is interesting. I sewed a batik block and all my seams were off and it needs to be taken apart and done over. I was using my soTT blocks to make pinwheels and I took a picture so I'll put it here. I still think Tommy Romano's cuts are smaller and if he uses a bigger seam allowance that would make the results even smaller. Cutting them out bigger, then using a scant seam allowance should make them bigger, No? Still confused and needing to sew to understand. In my quilting group they said sew, then measure, and fix. The block I did for fun is pretty, but it's very wonky. Will post a pic later. Going to exercise class for now.