Math help needed: reducing a block size
 

I have directions for a 15" block that uses lots of HST. I want to make it a 12" finished block. Simple proportions would be easy: 12/15 = 4/5= 80%, or reduce the block by 20%. However, since each piece has 1/4" seam allowances, I know there is more math involved.

Math and I stopped being friends in 4th grade.

Can someone please give me either a simple explanation on how to reduce such a block from 15 to 12" or a good link that explains it? One page I checked out did not account for HST.

Thank you to everyone whose brain works differently from mine .

THe block can be seen here:
https://blog.clothworks.com/tag/amer...december-2018/

The link had several quilts in it (a round one, the cover, and a twirl), I do have a subscription to that magazine so I may be able to look up the actual pattern -- is it the twirling one?

Going to find the magazine. It looks to me like it is a block divided in to 5 sections on point with a pieced sashing. I don't think 12 inches is going to be easy, 12.5 probably would be -- is that close enough? But people can be clever in how they design their blocks and I might be missing something.

So... reductions in general. I use graph paper, I have for 30+ years. Say you have a life sized block graphed out with 4 squares to an inch, well, you can reduce it by redrawing it using 3 squares as your "inch". You can use 5 square to an inch architectural graph paper instead for a small reduction, still using 4 squares on the smaller grid.

But the easiest thing to do is to take what you want over to an office store like Staples with a self service copier, or maybe your printer has easy controls to enlarge/reduce especially if you have scanning abilities. Libraries often have copiers as well.

And remember, while math may not be your friend, he isn't going to come over and beat you up because you ignore him :p

Good golly Miss Molly! Once I got the magazine I see that the Twirl pattern is indeed not what I thought it was! The block is "flat" not on point, it is not put together the way I would do it... I think your best bet is to draw it out with the measurements they list remembering to take of .5" for seam allowances (yikes, that will be painful) and then reduce it on a copier machine, don't forget to reduce the sashing units as well.

Basically 12 is 80% of 15. 15 * 80% (0.8) = 12

As an idea, the math for 12" means the orange squares in the sashing would be 1.2" finished instead of 1.5" finished (2" cut)

For example, the white print cutting instructions are
30 2-3/4" squares, so those would be 2.25
Then you get into 8ths....

Today is my small group day and I have to leave shortly. When I get back I can look at drawing the block up in EQ and then sizing it that way.

I think whatever you do the cutting will be painful and need to be precise. I think there are other ways to get the same look with easier cutting. That would be fairly easy to draw up but unfortunately I'm not willing to write up directions and cutting instructions for it.

PS: When I see how it is designed and the measurement used my brain tells me math is not my friend either... so I say go around it a different way!

It's a pretty block. Reducing a 3/4 square triangle can be a bit tricky but is certainly 'doable'.

Thanks. Yes, it is the "GIve it a Twirl" block. I was hoping to use it in my block swap after reducing it, but I see I could really be biting off a huge chunk of time and still mess it up royally

I think if you just want the block and not the sashing, it is doable in the 12" size, especially if we redraw it a bit.

It's rather clever the way the center square is made up of 4 triangles, if it was one piece and "set in" is that within your skill set or would you rather keep it the way it is? (If various people are making the blocks it is probably easier to do the way shown) I'd be making the triangles actual one piece triangles and not units that add up to a triangle.

If you divide the block into 4ths straight down the middle each way the construction would be a little different, you'd have to match the top part of the triangles onto the bases, but I think it would actually be pretty easy to put together.

Edit: So in fourths, each unit would finish at 6". You'd take a piece of blue that was 2" wide by 6.5" long. Add on a 2" white square on the end and sew through the diagonal. Then a yellow on the other side. The orange triangle would be 3" finished, for triangles you add 7/8ths instead of .5" for the seam allowance. Me, I would cut big at 4" and trim down.

Entirely doable that way at 12" but I gotta go!

Zozee, if you use your "proportion," be sure to do it with the finished sizes of the block, then add the quarter inch back on on all sides. This should theoretically work for curved seams also. Please let us see your result!

Linda in Missouri

Love that block but it sure looks complicated to make.

I tried drafting that block on graph paper. I got it to "work" on a l6 x 16 grid and on a 10 x 10 grid. Either way, the center square can be dealt with using the partial seam technique. I do not know how to get images from a Motorola phone onto the quilting board.

If the author made 15 inch finished blocks, I think she used a 10 x 10 grid with the blocks set on point.

Zozee, do you want all of it or only the twirly part in the middle?