There are different methods for squaring off bag bottoms. I am going to try to explain my method which may or may not be like anyone else’s.
I am not going to go through the process of getting to this point. Only from this point to make your bag bottom.
You will need:
Your bag with side seams and bottom stitched together
Ruler that is at least 4 to 6 inches X 4 to 6 inches. (mine is 4 X 13)
Pins
Fabric marking tool
Iron
Sewing machine ready to go.
At this point the bag will look very similar to this. Wrong side out and flat. Very flat. Pressed to the point of maximum flatness. The goal here is to be able to see the crease in the bottom.
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The next step is to press the seam open part way to the corner on the bottom. DO NOT trim the seam at the bottom or cut off the corner. This will be used in the squaring process.
Now with a bit of finagling (what a word) that seam is laid flat to the bottom of the bag and matched up with the crease to the seam. This is shown in the picture below The crease is shown with a purple line so it is easier to see. Then grab the point (shown in the last picture)of the seam and pull this point out so that the stitching is the point.
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Now the big decision-----How big do you want the bottom of your bag. I know decisions, decisions, decisions. Well now is the time. For purposes here we are using 4 inches.
The seam is laid to the side at the point and press making sure the crease and seam match (like above) and the stitch point is a point.
Now to make the bottom a bottom. You will need your ruler at this point. Line up a mark with the seam and 2” deep. When this is lined up perfectly it should also measure 2” either side of the seam. This is why it is so important to have the point really pointed. Whew I hope that makes sense.
I then mark this with a fabric marker, pin and stitch opening that seam to eliminate bulk. I usually sew across, pivot and sew back on this line.
Then press and turn right side out. You can trim off the triangle or leave it. Whichever method you prefer. Poke out the corners and press again.
Please give input. I would really like to know if there is something that is not clear and feel free to contact me with any questions.