how accurate is "accurate enough" ?
 

I've seen several posters say that the thread they use affects the accuracy of their piecing.

How much tolerance do you allow yourself on the "expected/hoped for" finished size of a block or completed item?

PS I am also a fan of Mary Ellen Hopkins "personal measurements" - but there are times when it's nice when a " group standard" is a good thing.

i want my blocks to finish within 1/16th inch of the measurement. however, some blocks that i've spent a very long time making have been 1/8 too small on some seams. when i realize this, i mark the spots with a pin, and when assembling the quilt, i sew a second seam to strengthen it. of course, this only works if you are pressing the seams to one side.

I have learned that you have to be as accurate as possible, the place i find out how accurate I have been always shows when I start sewing rows.

This is exactly what I do! I believe Mary Ellen Hopkin's idea of PPM's (Private Personal Measurements) for seam allowances only works out ok if you are sewing identically sized squares, and no other shapes within the quilt. It seems to me that for that to work, you need to have the same number of seams in each direction on the quilt. For most patterns, a perfect quarter inch seam allowance is necessary. There's just no getting around it, lol!

IMO -
The seam allowance is an important factor in accuracy , but not the only one.

Other factors:
Fabric preparation
Size of pieces - what one uses to cut with - how one measures
Pressing - can leave little tucks or pleats- can distort the unit
Thread used - some say this makes a big difference - I use a general purpose thread and have been okay with my results

What foot is it?

I have a Bernina and there are two 1/4" feet for it, one with a guide and one without. I have them both. Bernina feeds the fabric perfectly and makes a great stitch but is no different from other machines when it comes to perfect 1/4" seams. I have to use a self made guide on my Bernina just like all the other machines I have.

I use very thin thread in my bobbin, nothing under 60wt. That makes a big difference.

this is how I fix my inaccuracies as well.

I agree with this. Sometimes it is just not worth the effort to take everything apart if it is just a tiny bit off. :)

Sometimes my best intentions are to be accurate in my block sizes. But I allow myself some leeway. If it measures to within an 1/8" larger or smaller I am good with that.

I try and remember nothing is to be made perfect. To do so is comparing yourself to the creator.

I'm would like my blocks to be the correct size - the seam doesn't have to be the 1/4 inch - that is where MH personal measurements come in.

I don't worry so much about the final measurement most of the time. I just square them up to the size of the smallest block. If my seams are a tad over and the block comes out a bit smaller, I just make up the difference with the borders if I need it to be a certain size when finished. That is one reason I seldom cut the borders when I cut the blocks out. Just in case I decide to adjust it a bit. No matter how perfect you cut, the variance in the fabric can affect the size too. Some fabrics have more give to them.

If it looks good, I'm OK with it. Block size does not bother me as long as the blocks fit together and the points are pointy. I hate cut off points.

I am the worst person to talk about accuracy! BUT, as important as accuracy is, the most important is to be consistent. If you consistently sew a 1/4" or 5/8" or whatever, all your pieces are going to fit perfectly. Pick a measurement, whatever it is, edge of your sewing foot for example, and stick with it. The only time this does not work is in a group project. Good luck.

Consistency doesn't work if you are sewing shapes together. I have found that I have to maintain the scant quarter inch for them to fit.

Same here. I take full advantage of the little bit of stretch in fabric. I haven't had a problem with any quilt not lying flat when it's done so far.

As long as it lays flat , and the points aren't chopped off , is the measurement I use.

1. Quilting should be fun! 2. Nobody who gets a quilt from me,comments on the points as they snuggle under the quilt. 3. You can look at my quilting from 20 feet,for 20 seconds,with no glasses on!LOL. My quilting isn't perfect,but it's not too bad,and I'm not a competitive quilter.

I like Francie's answer. QUILTING SHOULD BE FUN !!!!! so don't worry about an exact measurement. I don't use a 1/4 " measurement, I use the edge of the pressure foot. That way I am consistent in the quilt and I square off with my rotary cutter anything that's off. The only time this would be an issue is if you were working on a group project, but wait....not all of their's are 1/4" either.

[ATTACH=CONFIG]425036[/ATTACH]It is #37 and I think it is called the Patchwork foot. That foot has a 1/8 inch seam allowance at the front edge as well as the notch lets you know when you are exactly 1/4 inch from the end of the seam. I find this very handy for stopping an exact 1/4 inch from the end when sewing my binding corners.

Most of the time having a consistent seam works fine for me. But a lot depends on the block. If you are making a very detailed block-many pieces, angles, etc.- you do need to have a very accurate seam to get everything to fit right. 9 patch vs mariners compass for example, one you are fine if you are consistant the other, not so much

Technically, the seam allowance doesn't matter at all. What matters is the measurement BETWEEN the seams. In my studio, it is either accurate or it is not, there is no 'accurate enough'. I could care less about perfection, but I'm committed to excellence.

How? there's no reference to which post you're replying to.........

The Bernina foot, right? Can't quite tell in the pic but would it fit on other machines or does Bernina use a different type of attachment?

I try for a perfect 1/4" seam allowance all the time simply because it prevents problems down the line. It is worth taking the time to perfect that seam allowance -- saves so much aggravation!

Having experimented with many methods, the one that *always* works for me is to create a physical guide for the seam. I used to cut adhesive moleskin (available in foot section of pharmacies), but now my preferred physical guide is this one: http://www.amazon.com/Dritz-Quilting...dp/B0085L2Y2I/ . With this in place my eyes are given relief (because they do not need to be glued to a mark on the bed of the machine) and I can sew very fast and still get perfectly even seam allowances.

Also, I have found that using fine thread helps a lot with my seam allowances. My favored thread is Aurifil 50wt 2-ply on top and in the bobbin (or 60wt bobbin thread in the bobbin). I think this helps because the turn-of-the-cloth is able to be ironed with more precision.

Recently I started piecing a kit and forgot to move my needle over one notch for the seam (necessary on my Bernina because of the relationship between the needle and the feed dogs). I did not realize it for a long time, when I went to match up seams and they didn't match. This was because every seam allowance was double a single needle-notch larger than they should have been. I should have ripped all my stitching out and started over! Instead, I decided to "adjust" the pattern as I went. It has been doubling my time at the machine; wish I had started over with the correct seam allowance. The pattern has lots of cornerstones, so it is tedious to adjust a seam every few inches!

In general, if blocks can fit together without ripples, I don't worry too much about exact size. I would guess I can adjust up to 1/4" difference in most 12-inch blocks without a problem. With 6-inch blocks, the tolerance would be closer to 1/8".

Edit: My experience with this quilt kit is proof that having a consistent seam allowance is not enough. It works for specific patterns, but definitely not for patterns that combine blocks with sashing and cornerstones!!!

As ghostrider mentioned:

The important measurement is the one BETWEEN the seams!

After making over 115 or more quilts, 10-15 comforters, and 10 or 15 biscuit quilts. I still can't make a perfect quilt. I keep trying but still can't do it. Lots are close but, no cigar.

all I know if it is cut correctly , sewing is a whole lot easier and it also looks better when finished

Sashing can correct a lot of errors. One LQS owner showed me how to sew sashing on the right side of a block, then on the bottom of the block then square it up. Do this instead of sewing sashing all the way across a row. This came in handy one time when I was asked to put blocks together that each block was sewn by a different quilter. It was a shock to see what a difference there was in seam allowances. The blocks were suppose to be 12 1/2" unfinished. Well, very few were. The blocks were anywhere from 11 1/4" to 15" (?). I had to trim down on several of them before putting sashing on like the 15" block.

I just did a tumbler quilt where I used a 3/8" seam allowance so that when I quilt 1/4" from seam, I will catch the seam allowance in it. Had no trouble putting the blocks together since they were not intricate piecing and all that mattered was consistency.

Also wanted to add that I like to over size the smaller blocks than square them up. Like making half-square triangles. To Make a 3 1/2" unfinished, I will cut squares at 4" rather than at 3 7/8". As I get older it's awfully hard to cut anything using the 7/8" line.

Accurate enough that any inaccuracy cannot be seen by a rider on a galloping horse! froggyintexas

I was replying to QuiltinNan's post about doing a double seam on thinner than desirable seam allowances. It's obvious if you read posts in threaded mode. Sorry you were confused.

I tend to reply like i'm in a conversation. I will make an effort to be more clear ;-)

I try to be pretty accurate, however I have vision problems so I just do the best I can and I don't stress about it. If quilting isn't fun any more I will do some other craft.

When do you use a scant 1/4" and when to use 1/4"? What is considered a thin thread? Does everyone use a different bobbin thread then top thread?

I have found thorough trial and error that thread size does affect the seam allowance. So I try to use the same thread throughout the piecing. With "So Fine" from Superior Threads, my seams are more true to 1/4" . With Connecting threads thread, I have to allow almost 1/16" to account for the width of the thread. Finished block size, I like to stay within 1/8" of what it's supposed to be, and I try ( notice I said TRY) to be extremely accurate when star points are right on the seam line. If they aren't quite to the seam line, I can live with it, but if they are chopped off, it really bothers me.

Tartan... thank you for showing that foot! I didn't realize the fact about the notch... very helpful! All these comments have been helpful... I am not a particularly accurate "seamer"... but I want to be better... every suggestion helps!! I DO enjoy the process, but want to get better...

I am OCD about my seams; I work as accurately as I can and then trim as needed. I don't to rip seams.

The importance of accuracy will show the most when you start putting blocks together. If your seams don't match up, there is a problem somewhere. If ALL your seams are the same little "one thread" off, they will match up exactly but your quilt may be a little smaller or larger when finished.