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# Thread: not so good with the math part!

1. I have some cut squares of nursery rhymes that are left overs from a panel. I would like to make a pinwheel block of the same size to make a baby quilt. The squares are 7 1/4" x 7 1/4" and that includes the 1/4 seam allowance. How big do I make the triangles to make a pinwheel block of equal size?

2. i would cut my squares 8" make the pin wheels then trim them to size.

3. Depends on how big you want your pinwheels. Two easy solutions are to cut out squares the same size you have. Put right sides together. Then you can either sew around the perimeter then cut the block twice from corner to corner. You will end up with 4 two-tone triangles that you can sew into pinwheels. Or, draw a line down the middle of one of the squares and sew a seam 1/4 inch on each side of the line. Then cut on the line to have two larger two-tone triangles. Repeat with another square and you will have 4 triangles that you can use for a pinwheel.

Hope that made some sense to you.

Rereading your question, I guess you don't want to use the squares you have in the pinwheels, so ignore what I wrote. The previous response was probably better. Make a bigger pinwheel and cut it down to the size you need.

4. Try a sample using 4-1/2 inch squares - you might need to trim up the finished block a bit - but not by much.

The reasoning behind that number:

7-1/4 inch block = 29/4

29/4 / 2 = 29/8 -> which is half the width of the block

29/8 + 1/4 (for the seam allowance on one side) + 3/8 (for the triangle point) =

29/8 + 2/8 + 3/8 = 34/8 = 4-2/8 = 4-1/4

Technically, a 4-1/4 inch square should work. I prefer to cut a bit larger and cut down the HST to size.

Your assembled HST squares should measure 3-7/8 inches before sewing them into the pinwheel units. (Assuming "perfect" 1/4 inch seams and other measurements)

5. Originally Posted by ckcowl
i would cut my squares 8" make the pin wheels then trim them to size.
Ditto

6. Originally Posted by Debbie B
I have some cut squares of nursery rhymes that are left overs from a panel. I would like to make a pinwheel block of the same size to make a baby quilt. The squares are 7 1/4" x 7 1/4" and that includes the 1/4 seam allowance. How big do I make the triangles to make a pinwheel block of equal size?

I would cut 2 of the background fabric and 2 of the pinwheel fabric into 4 3/4" squares, draw my line on the diagonal and sew 1/4" from either side then cut them down the center line that you drew. Each should end up at 3 7/8" and then when your pinwheel is together you would have the 7 1/4"

I always was told to add 7/8 to do a HST.

Does that help?

7. Will the "finished size" of your 7-1/4 inch squares be 6-3/4 inches?

Or another way of figuring it:

IF the finished size of the 7-1/4 inch squares will be 6-3/4 inches:

1/2 of 6-3/4 =

1/2 x 27/4 = 27/8 = 3-3/8 -> the finished size of the HST square unit

27/8 + 7/8 = 34/8 = 4-2/8 = 4-1/4 -> the theoretical size to cut the squares

8. double post

9. Thank you...going to try that.

Originally Posted by ckcowl
i would cut my squares 8" make the pin wheels then trim them to size.

10. Originally Posted by bearisgray
Try a sample using 4-1/2 inch squares - you might need to trim up the finished block a bit - but not by much.

The reasoning behind that number:

7-1/4 inch block = 29/4

29/4 / 2 = 29/8 -> which is half the width of the block

29/8 + 1/4 (for the seam allowance on one side) + 3/8 (for the triangle point) =

29/8 + 2/8 + 3/8 = 34/8 = 4-2/8 = 4-1/4

Technically, a 4-1/4 inch square should work. I prefer to cut a bit larger and cut down the HST to size.

Your assembled HST squares should measure 3-7/8 inches before sewing them into the pinwheel units. (Assuming "perfect" 1/4 inch seams and other measurements)

***********************************************

Will the "finished size" of your 7-1/4 inch squares be 6-3/4 inches?

Or another way of figuring it:

IF the finished size of the 7-1/4 inch squares will be 6-3/4 inches:

1/2 of 6-3/4 =

1/2 x 27/4 = 27/8 = 3-3/8 -> the finished size of the HST square unit

27/8 + 7/8 = 34/8 = 4-2/8 = 4-1/4 -> the theoretical size to cut the squares
YOU ARE ONE SCAREY LADY!!! I'm still counting on my fingers!

11. Gotta get some good out of all those remedial math classes I took!

I used quite a lot of scratch paper to try to get the same answer twice!

12. I found some documentation for HST's it says always add 7/8s to the size of the finished block that you want and you'll get the perfect HST.

13. Thank you, this sounds like a good formula.

Originally Posted by Ripped on Scotch
I found some documentation for HST's it says always add 7/8s to the size of the finished block that you want and you'll get the perfect HST.