Question on HST's
 

I'm making a scrappy quilt with 1280 half square triangles. I have all my squares cut, now my next step is to take that little ruler (there's a name for it but I don't know what it is) and put it down the diagonal of each square, then draw a line on each side of the ruler, then stitch on each line and then cut the square down the diagonal.

Question for you - it would be much faster if I could cut down the diagonal first and then chain piece a quarter of an inch from that cut edges on each of the pieces. The end result would be the same, wouldn't it? Any reason why I shouldn't do this?

I'm cutting each square a little bigger than it needs to be so after all of the above I still have to take each of the 1280 hsq's and cut them to size. This is turning out to be quite a project and I'm hoping to save a step here. Seems that step of drawing the line is kind of "extra" but I still new at this so maybe I'm missing something.

If you cut first, then plan to sew, you should pin and that is where you will lose time. It really is a time saver to draw a diagonal line, imho.

It won't be faster because you will be dealing with 4 pieces instead of 2.
Also, when you are sewing on the diagonal there is less risk of distortion
when you are sewing across the square than sewing on a bias edge.
Try it both ways and see for yourself.

As EasyPeezy suggests, do a timed trial for yourself to see what works. I find that I can cut out the line-drawing step if I use a simple tool called the easy-angler (or maybe it's the EZ angler). It's a piece of clear plastic with line markings that you align to your machine bed and then you can just guide your 2 squares along the lines of the tool rather than deal with markings.

You can also draw your line from corner to corner and stitch 1/4 inch on each side.

Right ... or place the 1/4" measurement on the center line then draw you're left line, turn the ruler and place 1/4" measurement on the center line and draw the opposite line. In short .. you really don't need to draw three lines.

As the others said though, cutting first and sewing second leaves a large chance that you will distort the pieces because you will have a raw bias edge.

You will still need to measure if you cut them and then sew. Actually, you will be making two at a time when you mark your line and then sew. For this I would mark one diagonal line then line up your foot and sew 1/4 inch from the line. Hopefully you have a 1/4 inch foot for this project. Trying to aim for accurate triangles would save you more time than having to cut down each one. (IMHO) Good luck on your project:)

I saved a lot of time on these by putting masking tape on my machine. No need to draw on the fabric.

http://www.craftsy.com/blog/2013/04/frog-tape-trick/

Thank you for your replies!! Here's my reasoning on the time saving thing.

If I go by the rules here is how it goes, I already have the squares cut up and put in pairs of light on top of dark -

I take each pair, place the Fons and Porter ruler on the diagonal, draw a line on each side of the ruler(each line is 1/4 of an inch away from center).
Stitch down each line (two lines of sewing for each square)
Cut each square on the diagonal.

And my short cut method
Cut each square on the diagonal so I am left with two triangles
Stitch 1/4" from each diagonal cut (I do have a 1/4" foot)

With the second method I save that entire first step which is a lot of time when I have 1000+ of these to do. But I know there is some flaw in my logic because I never, ever hear of it being done this way. A couple of you mentioned that the fabric may become distorted so I'm thinking that is the main reason it is not done this way. But on the other hand my squares are only about 3" - can they become distorted at this small size?

I've always done it the "long" way so in the end I will probably stick to it. The EZ angler - I don't think I've heard of this. Sounds like it eliminates the need to draw the lines, right? and instead it guides you as you stitch 1/4" from the center diagonal? If I understand it correctly sounds like it saves time. Best of two worlds, you don't have to draw lines but neither will the fabric become distorted.

I think this is the way Bonnie Hunter does it and she doesn't use pins.
Here is you-tube video about how to use the easy angle ruler.https://www.youtube.com/watch?v=nXN8M8cn1HQ