You really dont need a 90 degree ruler. you can use any ruler that has the 90 degree line on it.

You really don't need their fancy ruler. Most rulers have a 45 degree angle (all Omnigrids have it), which is what you need. You line the 45 degree mark on the edge of the fabric and the edge of the ruler now sits right where you need to mark. See the picture below. Use the angle marked on the ruler for your fist line and just use the ruler to mark the rest of the lines evenly spaced.

You are so smart I never thought about that. Oh well I did it the old fashion way. Thanks, I'll try and remember that the next time
You are all so helpful

In the "old days" they had ways of folding the fabric and cutting just by marking the fabric and cutting, didn't need a fancy ruler. Works too. I used to find it in some of the older quilt books.

Missoui Star Quilts has a tutorial. They sell a ruler. It is call the Bias Ruler. I have one. It works.

thank you so much for the link!

Maria, this is a great tip. I watched the video and now feel like I could do this. Thanks all for your suggestions.

Thanks will look into it.

I always use bias binding.....never straight. Why??? Have you ever seen those old quilts where the binding rips along the binding fold? That's because with straight binding, there is only one thread running up and down that fold. With bias binding you have hundreds of threads ..... like a million of x's...... more strength .... it won't rip along the fold.