Until now, all of my quilts have been designed with squares, strips, or rectangles. When working with triangles, my pieces don't lay flat. Comments, suggestions, TIPS

First off, do you starch your fabric? You're working with the bias, so starching heavily helps tremendously. Are you making the triangles the easy way, by cutting 2 squares, sewing diagonally on both sides of the line, then cutting? That's my 2 suggestions.

Welcome!

Welcome from Il. I fine taking one step at a time and press press press.

Hi and welcome from the sunny state of Florida!!!
It sounds like you're not sewing your seem straight. It takes practice. I just make a square & sew on both sides of the line & cut, voila, you have 2 HST's in one.

Thank you everyone. The concensus is to stitch before cutting, which I was not doing. I'll try that the next time. Plus for extra measure, I'll starch.

I realized I did not introduce myself. Top end of my youth at 60. I am a grammy to one 17 month old little boy, who is an only child of two only child(ren). They live just outside of Boston and we live in the Chicagoland area; so there are not a lot of visits.

I have always loved to sew and taught my daughter to sew. Poor kid growing up, mom made all of her dress/party clothes. But all of her friends envied the way it fit her torso. I digress...

I have many several baby quilts and have two more on the sketching board to construct between now and January. But I have to work on a big boy bed quilt first. I am very excited to be doing this quilt for him; lots of color and lots of trucks, cars and planes in the material. I am hoping this is going to be one that I photo and post.

DH has been encouraging about the quilting and the mess; but I'm sure he'd prefer it confined to 1 room not spread over the whole house. He has a hard time conceptualizing a block when I ask him to look at just the uncut material. But his eye is good when looking at the layout, helping with borders, quilting designs.

Welcome to the board from Southern California!!!

you have to plan a little bit to stitch your 1/2 square triangles, but if you cut 2-4" squares; place them right sides together, draw a diagnal line across the lightest one, stitch 1/4" on each side of the line, press flat to set the seams, cut on the line, press open;
when you trim you should have 2- 3 1/2" (1/2) square triangles...perfect & easy :)

Welcome from Ireland.

Hi and welcome.
The first thing that popped into my head was are your seams straight.