Are you by any chance engaged, like I am, in making 1,532 half square triangles for Freckled Whimsey's Charm Pack Quilt Along? (Yes, you're right. I'm exaggerating the number--slightly. I'm actually making 216 half square triangles because I'm making mine 6 blocks across by 6 blocks down; it just FEELS like 1,532 of the suckers!)
Well, that reminds me. A week or so ago, Gran was talking about drawing diagonal lines on the backs of squares--I think she was talking about the Joy Luck Schnibbles. "No, no, no," I told her. "Just slap some masking tape on your sewing machine." "Huh?," she asked (or words to that effect). So as we sat in her car after returning home from Benicia, I quickly tried to show her what I was talking about using some props--whatever was sitting in her car that could be used as a straight edge and an imaginary sewing machine needle. ("Quickly" because it was probably about 95 degrees out and I wanted to show her before we sweated out all of our bodily fluids.) But YOU, my little Blogettes--for YOU I have photos! Nothing but the best for you, I say! So for you, I have a little tutorial that might make life a little easier.
Before we begin, here's a photo of the "lines" on my sewing machine. (Well, the lines are actually on the acrylic TABLE, but you know what I'm saying.) Can you see that they're just about 1/4" apart? The lines serve two different purposes. First, the masking tape on the right is the one I recommended to Gran. This is a great (not to mention CHEAP) tool for stitching a straight corner-to-corner diagonal line for connector corners or other diagonals where you're just making one stitch line.
To place that piece of masking tape in position, line up the edge of the ruler with the needle hole in the plate and make sure the ruler extends straight to the edge of the table. (It should line up with all the lines of measurement on the plate.) Stick down the tape, following the edge of the ruler. To use the tape to make diagonal stitching lines, position one corner at the needle and line up the opposite (diagonal) corner with the tape. It won't work if your square is HUGE and extends past the edge of the lines, but it will do fine for smaller squares.
Now, the second masking tape line for the second purpose. This is the one that will help you make two plain squares into half square triangles without drawing a line on the back of one of the squares. For this piece of tape, place it to the left of the first piece of tape, with a 1/4" space between the two. Does that make sense so far?
Without a drawn line, it's all about lining up the fabric with the masking tape references to stitch a straight line. And to give you a little visual reference here, I've marked a little line where the stitching will end up--this is 1/4" to the right of midline. See how the corner of the square is at the edge of the left-hand tape and the line is at the edge of the right-hand tape? Although this photo doesn't show it, I've also lined up the top corner with the left side of my quarter inch sewing foot, so the needle will go into the fabric at a point that's 1/4" to the right of center. (You can see that a little better a couple photos down.)
Now I just keep feeding my squares through the machine, lined up as I've shown you--no need to take the time to draw lines on the backs of the squares.
Once I've stitched a bunch and am getting bored and fidgety, I turn the whole thing around and do it all over again on the other side of the imaginary center line. (In this photo, you can see where I position the top corner.)
Once I reach the end, I cut down the centers between the stitched lines and press the squares open. Ta-da! Half square triangles, the no-muss, no-fuss way! Now I just have to trim them to size.
Hey! Where'd THAT pile come from?! I thought I was done! Well, at least I don't have to draw those darn center lines!