Scant quarter of an inch
#11
Junior Member
Join Date: Dec 2013
Location: Minnesota
Posts: 166

I have a 1/4 foot on my machine. I move the needle over to the right just enough so that my blocks come out to exactly the size i need them to be. Before I moved my needle over it seemed that some of my blocks would be just 1/8 inch shy of the right size. Now if they are a little off it will be a tiny bit too big and then I can trim it away if I want.
When working on small projects it helps if they are all the same size and that some are not 1/8 inch too small.
When working on small projects it helps if they are all the same size and that some are not 1/8 inch too small.
#12
Junior Member
Join Date: May 2014
Location: Maumee, OH
Posts: 289

My understanding is that the "scant" 1/4" seam allowance works because the "turn of the cloth"- fold takes up a small amount. If the seam allowance is slightly less than 1/4" the finished block will be closer to the actual size block one is trying to accomplish!
#13
Power Poster
Join Date: May 2008
Location: MN
Posts: 24,233

I think the "issue" starts with the size of the cut pieces.
For example: even though I think I cut "exactly" - when I measure my 2-1/2 inch strip - it is actually about 2-9/32 inches wide - about a rotary blade's thickness wider than the template.
So I can use a "regular" 1/4 inch seam - and when sewing non-bias edges together - the unit usually ends up being the size I am aiming at. There is enough "extra" in the way I cut to allow for the thread thickness and the amount of fabric taken in the turn/fold.
If my cut pieces were EXACTLY 2-1/2 inches, then if I used an EXACT 1/4 inch seam, there would be some "loss" when I pressed the unit - the fabric has to turn and accommodate the thread - and the result would be less than 4.5 inches - as Dunster said.
I think the place to start is to measure the size of one's cut pieces. A couple of threads here and there can make a difference in the finished size of the unit.
For example: even though I think I cut "exactly" - when I measure my 2-1/2 inch strip - it is actually about 2-9/32 inches wide - about a rotary blade's thickness wider than the template.
So I can use a "regular" 1/4 inch seam - and when sewing non-bias edges together - the unit usually ends up being the size I am aiming at. There is enough "extra" in the way I cut to allow for the thread thickness and the amount of fabric taken in the turn/fold.
If my cut pieces were EXACTLY 2-1/2 inches, then if I used an EXACT 1/4 inch seam, there would be some "loss" when I pressed the unit - the fabric has to turn and accommodate the thread - and the result would be less than 4.5 inches - as Dunster said.
I think the place to start is to measure the size of one's cut pieces. A couple of threads here and there can make a difference in the finished size of the unit.
#14
Power Poster
Join Date: May 2008
Location: MN
Posts: 24,233

1/32 of an inch is not very much - but say the block is made 12 strips that are cut at 1.5 inches.
If one loses (or gains) 1/32 on each side of the strip - that would be 1/16 of an inch on each strip - and there are 12 strips
12*1/16 = 12/16 = 3/4 of an inch.
The variance can be cumulative - If one was planning to alternate plain squares with the stripy units - it could be a bit of a problem.
(Although I did see "somewhere" - to make the units of the smaller pieces first - and then cut the bigger units "to fit")
If one loses (or gains) 1/32 on each side of the strip - that would be 1/16 of an inch on each strip - and there are 12 strips
12*1/16 = 12/16 = 3/4 of an inch.
The variance can be cumulative - If one was planning to alternate plain squares with the stripy units - it could be a bit of a problem.
(Although I did see "somewhere" - to make the units of the smaller pieces first - and then cut the bigger units "to fit")
#15
Power Poster
Join Date: Jan 2011
Location: Southern USA
Posts: 15,488

This is why I love die cuts. 99% of my cutting is with a Go. Every piece is exactly the same. I can tell immediately if my seam allowance is off. If there is a measurement I don't have for a quilt pattern I have a custom die made. I haven't found that many quilt patterns there isn't a die for, maybe a different size block so I make more or less of them. I seldom use my rotary cutter unless I'm using a specialty ruler.
#16
Super Member
Join Date: May 2013
Location: Ballwin, MO
Posts: 4,108

I think putting the focus on the measurement of the seam allowance is what confuses people. It doesn't matter what the measurement of the seam allowance is. What matters is the size of the finished block. The question to ask is, 'What seam allowance is going to result in the block being the size it is supposed to be?"
You have to experiment to see where to set it on a particular machine. Someone recently posted a video that suggested cutting a nine inch strip of fabric, and then cutting nine 1 1/2" strips of fabric, sewing the 1 1/2" strips of fabric together, comparing that length to the 9" strip, and adjusting the seam allowance until the sewn strip matches the 9" strip. Whatever that turns out to be, that's your 'scant 1/4" seam allowance'.
You have to experiment to see where to set it on a particular machine. Someone recently posted a video that suggested cutting a nine inch strip of fabric, and then cutting nine 1 1/2" strips of fabric, sewing the 1 1/2" strips of fabric together, comparing that length to the 9" strip, and adjusting the seam allowance until the sewn strip matches the 9" strip. Whatever that turns out to be, that's your 'scant 1/4" seam allowance'.
#17


#18

Even if there were no need for a "scant" 1/4", being consistent is not enough when you are dealing with more complicated blocks. Suppose you decide to sew 1/2" seams instead of 1/4". If you make a 9-patch it looks fine. If you make a 4-patch it also looks fine. But now take a 9-patch and a 4-patch that were supposed to be the same finished size and try to put them together. It won't work, because there are 2 seams going down the 9-patch and only one seam going down the 2-patch! This is an exaggeration, but the theory holds even if your seams are only 1/16" too large or too small.
The lesson to take from this is that you need to measure your block as it is formed to be sure your units are measuring correctly. The seam size needs to be adjusted so that the *finished* patch is the right size.
The lesson to take from this is that you need to measure your block as it is formed to be sure your units are measuring correctly. The seam size needs to be adjusted so that the *finished* patch is the right size.
#19
Power Poster
Join Date: Jul 2008
Location: East Oklahoma - pining for Massachusetts
Posts: 10,477

If it makes you feel any better, I have been quilting since 1992, and I have yet to achieve a quarter inch seam. I am just happy they go together and look okay when finished. This does preclude me joining exchanges, but am okay with that.
#20
Super Member
Join Date: Oct 2010
Location: Nebraska
Posts: 3,248

I sure try very hard to do a straight 1/4 inch seam
Each time the subject of the "scant 1/4" comes up, it makes me nervous. I don't know why I read it! Anyhow, to each his own and I will never be perfect
But I sure enjoy the things that I make. You all go for it and enjoy!


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