I need help with cutting calculations
 

I'm making 12" finished blocks set on point so I need the calculations for making the setting triangles and cornerstones. BUT the setting triangles and cornerstones are made from a nine patch with a four-patch in each corner. Hope this makes sense, I don't have access to a scanner to show the actual block.

With a complicated design like this, I think we need a picture or link.
If you don't have a pattern, what I would do is make a full block for your first setting triangle & starch the heck out of it. Mark the diagonal, then sew a line of stay stitching just to one side of the diagonal. Then cut it. but NOT IN HALF, remember to add the 1/4" seam allowance past the diagonal line. Your setting triangle will have a bias edge, but with the stay stitching & careful handling you should be OK. Use this cut triangle as your pattern for the rest of the settings.

http://www.quiltingboard.com/attachm...d=497216&stc=1they would be something like the ones i made up.

Perhaps these graphics will help you visualize the process.

Jan in VA

I always hated trying to do the match so I bought one of those large acrylic triangle rulers that have the lines that coordinate with cutting the setting triangles. Good job with the written explanation Jan !!

jan, great explanation! your drawings are always so clear :thumbup:

Here's the block I'm trying to cut in half for the setting side triangles and in fourths for the corner triangles. The finished blocks are 12" set on point.

So aren't the point going to be cut off when you sew it if you cut this on the diagonal twice? Maybe I am not seeing it ...

OMG Jan how do you do this???? you need to move next to me in California :-)

Yes that's the problem. This is a quilt I'm doing from a shop and she gave us this pattern for the setting blocks and to use as the setting triangles. I saw on the shop sample the points were cut off and her response was no one would notice. I noticed it and anyone with any quilting knowledge would notice. I want to make them right.