Exploding Block Tutorial

I first read about how to make this block in a book but I then came across this video, Exploding Block,  by Jenny Doan from the Missouri Star Quilt Company. It’s fast and fun, however I use a different cutting technique that is easier for me so I thought I’d share.  Watch the video first, then you’ll understand the difference.

In the video to begin the block you sew two squares right sides facing, stitching all around the outer edges. After drawing diagonal lines on one of the squares you then pinch it up and cut it with scissors to fold it out for your first “exploding” layer.

Here’s my technique:  BEFORE I sew my first two squares together,  I mark the square that will be cut on it’s back side, drawing a line 1/4″ from the edges and then two diagonal lines from each corner, like below:

Tut 04

Using a rotary cutter and ruler, I cut on my diagonal lines starting and stopping a “scissor snip” length from the corners (about one inch), like so:

Tut 05

Then, I sew my two squares right sides together all around the edges.  Doing it this way requires only one short snip to be made before folding out the edges.   Less chance to accidentally cut through the front square or cut wonky, longer lines.

Tut 07Tut 08

Tut 09

For every additional “layer” I add, I cut this same way first, before sewing it face down to my other pieces and folding out.  If you decide to make blocks using the “exploding” technique I hope my cutting tip helps you out!

Exploding Pineapple Quilt Block


48 thoughts on “Exploding Block Tutorial

  1. Deanna Edgington

    I am sewing a block in block guilt right now
    I wish I would have seem your post earlier. Your idea would have saved soo mush time and
    Made perfect blocks . Will use your idea
    Next time. Thank you for sharing ‘ genius!!

  2. Sen

    I’m stunned this would even be put forth as a method. It’s mathematically doomed from the start, as evidenced by every single point being obliterated systematically. I can’t believe anyone would advocate such a time-wasting convoluted method to get such consistently poor results. Criminy! Just incredulous here! In order for the square that is cut into quarter-square triangles to actually produce points, it needs to be 1 1/4″ longer on the straight edge than the center square. Double-check any 7th grade geometry book, or pick up Donna Lynn Thomas’ book “Shortcuts, A Concise Guide to Rotary Cutting” and learn some basic math concepts. It’s extraordinarily disheartening to see “professionals” in the industry disseminate bad math and sloppy techniques in the name of speed. Take a little pride in your work; show some respect for the monetary investment as well as the skills of the quilters you are addressing.

    1. Sen

      To clarify measurements: if the finished center square is 3 inches then it’s cut size would be 3 1/2 inches (using a standard 1/4 inch seam. In order to take another square and cut it into quarter square triangles for use, with the longest edge of the triangle to also be finished at 3 inches, that square would have to be cut 4 1/4″ to accommodate the 5/8″ loss that comes at either long tip when using a 1/4 inch seam. Before you waste time on the bogus method put forth in this article; take the time to cut a 3 1/2″ center square, and to cut 4 quarter-square triangles from a 4 1/4″ square. Mark a quarter inch seam around all pieces and then join and press them. You’ll sew pretty little crisp points with a 1/4 margin all around them sew they can be sewn together without loss of the points.

    2. denmck Post author

      What a very interesting comment you’ve made. First, this block is NOT intended to have points. So for you to rant about how awful it is to have a block that sews together squares in this manner and does not produce points is very odd. The original designer of this block pattern had no desire for the block to end up with points. It’s a design decision that she made and shared with others. There are lots of other quilt block patterns that end up with nice, crisp points if one wants them. Don’t use this pattern if you don’t like the results but don’t criticize others that are happy with how their quilts turn out using this block pattern. There is no need to clarify measurements because obviously you are trying to make a different block. Did you watch the video link?

      1. Sen

        My apologies, it’s obvious you’re okay with selling the bastardization of the block as, “it’s meant to be that way.” Call me a purist. I’m okay with the Bob Ross “happy accidents” concept so long as it’s not being sold to newer folks as “no, really, it’s meant to be like that.” Guess I just have a thing about making points, eh? Feel free to delete the information in the name of pointless propaganda. The information is out there in enough other places. Happy pointless quilting! 😉

        1. denmck Post author

          To each their own. Any way that a quilter decides to design and make their own quilt blocks is fine with me. It’s called creative expression. I’m not going to censor the sharing of someone else’s ideas or methods because I may not want to do it that way. I’d rather be open to all the possibilities. It’s much more fun that way!

  3. Angie Bowling

    I agree with your version of cutting the one square before sewing them together. It is too easy to make a mistake and cut through and them ruining the square.

  4. Judy

    Thank you for this great idea. I have been wanting to make this block and now I will have more success thanks to you. 😊

  5. Lesley Gilbert

    I made a quilt top last year using something like this method, but not cutting the squares before sewing each block together – I shall try this method next time, thanks 🙂

    1. denmck Post author

      The block pictured ended up approx. 13 x 13 which includes the 2 1/2″ strip border. I believe I used a 4″center and another 4″ block for the first “layer”. After that was cut and folded out the block became about 5 1/4″. So I cut the next block to equal 5 1/4″ and after sewing, cutting, and folding out the block equaled about 6 3/4″. I added one more layer and ended with a total of about 8 3/4″ before adding my border.

    1. denmck Post author

      This block was designed to have blunt points. If you would prefer sharp points you may want to make a Square-in-Square, or Economy Block instead.

  6. Patti Cobbin

    OMG this could very well be my next quilt project….continue growing the one block until it’s large enough to be a quilt top! Thank you so much for sharing this wonderful tutorial! 😀

  7. betty frye

    I made a baby quilt using pastel solids.from the square in square block you cut from corner to corner to get squares in middle then you mix them all up and sew back together. Makes a beautiful colorful quil

  8. CraftALife

    Wouldn’t doing this mean you will always cut off your corners of the inside square when you sew the next pieces on!?

    1. denmck Post author

      If I understand the question, that is right. You don’t get “points” on your corners, they are blunted, which is the way this block was designed to be. A standard “square-in-square” block gives you a sharp corner. Like the examples I show on the Economy block comparison post from January, 2014.

  9. Joy

    I’ve just stumbled across your site (I love google meandering) and this tip you’ve shown is brilliant. I think this will be my next quilt fix!

  10. Anonymous

    Great idea! I just saw that tutorial and wanted to try it, wasn’t looking forward to the cutting like they did it! This makes it much easier!


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