Making a 16 patch block. Am I doing something wrong?
 

I make these a lot but I wonder about my results.

I just made a bunch of blocks. I started with 3" cut strips. I strip pieced them into groups of 4 then sub cut them at 3". I sewed them together to make a 16 patch.

After I pressed them I had to trim them. They trimmed down to 10" square which is my issue. They should theoretically be 10 1/2" finished size right? Because the outer squares do not have a 1/4" seam yet. Once I sew these finished blocks to the next component, the outer squares will end up a tiny bit smaller than the inner ones. Or am I figuring something wrong?

I've made many quilts with the 16 patch block. Once the quilt is assembled it's hard to see that the outer blocks are a tad smaller than the inner so I'm ok with it in practice. But I have a feeling this is not right.

I looked at some blogs and they say with 3" cut fabric, I should get a 10" square block which I do. But what about the size of that outer edge?

Am I doing something wrong?

Yes, you should have 10 1/2 inch unfinished square when all are sewn together.

Not sure what is going on but if they look good in the end I wouldn't worry about it. Doesn't sound like they're off that much.

Have you measured the width of the 4 strip before sub-cutting? Does it measure 10 1/2". Perhaps your seams are a tad more than 1/4".
Or - have you tried a scant 1/4" seam. Maybe the 'fold' of the fabric with so many seams takes up that bit extra when all is put together. I sometimes find using a finer thread in the bobbin makes a difference .

Thanks for the replies.

Yes Sandra B, I thought they should be 10 1/2".

And yes SusieQ, in my case it doesn't matter a lot. I was just wondering....

And no Gay, I have not measured my strips. That's a great idea. I hope I remember to do that next time I make a 16 patch.

It's probably my seams. Just a little bit off makes a huge difference in the end.

It does sound like the (unfinished) block should be 10.5", so that the finished block will be 10".

Sometimes it's easiest just to compensate for things, like cutting HSTs a little bigger than they theoretically need to be so that they don't end up too small (which I do). If it's just the outer squares of the 16-patch that are too small, cut those bigger to start with so that they end up the correct size.

I would measure each individual square (of the inner squares) to make sure they're really 2.5" each first. Then you can be sure that the problem is just with the outer squares of the block.

But like SusuiQOH said, I wouldn't worry about it too much since it looks fine when it's all finished.

They should be 10 1/2. Don't measure the seam, take the first 2 strips after they are sewn together, press them, then measure across. They should measure 5 1/2. If they don't, adjust your seam until they do. My pieces were never the right size when I measured the seam. When I finally realized I should measure the unit, things started fitting much better. Hope that makes sense.

last time I made a block I was off 1/2 inch. Went back to look at what I did....My ironing needed HELP! Spritz and repressed. Voila...right size block!

I found some 4 patch strips that were not wide enough for my quilt in my fabric discards and measured them. As suspected, they were less than 10 1/2" long. So that's the problem - my piecing.

Thanks for all the help.

Here's a link to the video that helped me: https://www.youtube.com/watch?v=XzliXPyWmbk&t=10s
It was one of those "duh, why didn't I ever think of that" moments when I watched it.