Math no being my strong point.
 

I would like to make hour glass block to finish at 10.5". I also would like to make it the way Jenny Doan does on her tutorial with the layer cake. But being challenged in math can't quite figure it out. Any help would be appreciated.
Thanks in advance.
Connie

I can't figure out math either. Usually blocks don't finish in half inch increments. I haven't watch that particular video yet.

MQ2 thanks for bringing the finished size to my attention your are right 10 sq. finished. Sew 10.5 raw edge right?

Just some clarification. Do you want to make an hour glass block, or the disappearing hour glass block?
If it's just an hour glass block, you want the finished size (sewn into the quilt) to be 10.5", correct?
Same question about the disappearing hour glass block. you want it to be 10.5" when sewn into the quilt (that's what finished means: sewn into the quilt)

I tried to link but I believe you add 7/8" to your square then you will cut on the diagonal. Could try a piece of paper then fold back the center then sew 1/4" seam allowance from center line down both sides. Or use a scrap of fabric you don' like. So your square of fabric would be 11 3/8''. Could not get measurements and thought I had a chart bookmarked but can't find it.
Sorry!

yes I want to make just the hour glass block. ManiacQuilter2 pointed out to me that I want it finished at 10". Sorry for the confusion.

only mention Jenny had was a layer cake. Thought you wanted 10,5 finished. I have couple patterns that are to finish on .5 increments. sorry no help again. Anxious to see other comments.

No problem!
OK. So you want a 10" finished Hourglass block constructed using the HST method that Jenny Doan uses.
This link gives a chart and the formula:
http://www.blossomheartquilts.com/20...maths-formula/
Scroll down to Alternative HST method.
You want your block to finish at 10". The block is made up of 4 HST. So each one needs to be 5.5". When they are sewn together, the raw block is 10.5", which finishes at 10".
Using the info from the chart found at the link, you would cut your starting squares at 8.5", sew around the edge, cut diagonally both ways press, then trim the resultant triangles to 5.5".
PLEASE make a sample to verify the numbers!!!

Thanks PaperPrincess!
I will give it a try first thing in the morning.