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Thread: So much for my math ...

  1. #1
    Senior Member CompulsiveQuilter's Avatar
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    Converting a 12" block to a 6" ... divide in half and add 1/2", right. Easy peasy. WRONG. I still don't know what happened; too mad to mess with it right now.

  2. #2
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    Take a deep breath you will get it. Try, try and try again. BrendaK

  3. #3
    Senior Member yellowsnow55's Avatar
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    :oops: I would've done the same! Thanks for the warning.

  4. #4
    Junior Member PrettyCurious's Avatar
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    If you place a 6" square piece of paper on a 12" one, you will see you needed to divide it by 4, then add your 1/2" seem allowance

  5. #5
    Thusnelda's Avatar
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    Quote Originally Posted by PrettyCurious
    If you place a 6" square piece of paper on a 12" one, you will see you needed to divide it by 4, then add your 1/2" seem allowance
    Sorry to object, but you have to divide the length measurements by two otherwise you end up with a 3" block. CompulsiveQuilter seems to have done it correctly but somewhere a mistake must have snuck in. What kind of block was it and what size block did you end up with? Maybe we can work out the mistake when we know the details.

  6. #6
    dd
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    Super Member dd's Avatar
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    I can "see" divide it by 4 but it doesn't make sense in my head. Why does that work? Six is half of 12. This makes my brain hurt.lol

  7. #7
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    It is hard to give advice unless we see the block.
    Depends on if it is a square or a star.

  8. #8
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    Did you divide the original measurements for the 12" block, the ones that included the necessary seam allowances for the 12" block?

  9. #9
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    Are you trying to reduce/enlarge individual pieces or the whole block at one time?

  10. #10
    MTS
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    Quote Originally Posted by PrettyCurious
    If you place a 6" square piece of paper on a 12" one, you will see you needed to divide it by 4, then add your 1/2" seem allowance
    The op is talking about the individual pieces that make up the block.

    So if you have a four 6" finished blocks making up a 12" block, you do want to divide each piece by 2 and add the seam allowance.
    That will give you four 3.5" blocks, which will make a finished 6" 4-patch block.

    Your way would have four 1.5" blocks, with a finished block size of 3", which would be too small for what she wanted.

  11. #11
    Super Member GingerK's Avatar
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    Get out the graph paper and draw it out as a finished 6" block. Then measure the individual pieces and add your 1/4" seam allowances. Over the years I have found that true quarter inch graph paper is my best friend in the sewing room--well that and my seam ripper!

  12. #12
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    Quote Originally Posted by GingerK
    Get out the graph paper and draw it out as a finished 6" block. Then measure the individual pieces and add your 1/4" seam allowances. Over the years I have found that true quarter inch graph paper is my best friend in the sewing room--well that and my seam ripper!
    I LOVE graph paper.

    There is something about drawing the lines in oneself that is very enlightening. (Enlightening isn't exactly the word I want, but it's the best one I can come up with at the moment)

    Make sure your graph paper is "true" - some of them are off a little bit. Take any ruler and put it on top of the paper in both directions. The paper I'm using now lines up exactly with my ruler in the vertical direction - over an 8 inch width in the horizontal direction, it's accumulated about 1/16 inch variance.

  13. #13
    Senior Member laparshall's Avatar
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    Quote Originally Posted by GingerK
    Get out the graph paper and draw it out as a finished 6" block. Then measure the individual pieces and add your 1/4" seam allowances. Over the years I have found that true quarter inch graph paper is my best friend in the sewing room--well that and my seam ripper!
    I agree about the graph paper and the seam ripper.

  14. #14
    Power Poster QuiltE's Avatar
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    Quote Originally Posted by bearisgray
    Quote Originally Posted by GingerK
    Get out the graph paper and draw it out as a finished 6" block. Then measure the individual pieces and add your 1/4" seam allowances. Over the years I have found that true quarter inch graph paper is my best friend in the sewing room--well that and my seam ripper!
    I LOVE graph paper.

    There is something about drawing the lines in oneself that is very enlightening. (Enlightening isn't exactly the word I want, but it's the best one I can come up with at the moment)

    Make sure your graph paper is "true" - some of them are off a little bit. Take any ruler and put it on top of the paper in both directions. The paper I'm using now lines up exactly with my ruler in the vertical direction - over an 8 inch width in the horizontal direction, it's accumulated about 1/16 inch variance.
    <----- tossing the word empowering for Bear!!

  15. #15
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    empowering is a good word - thank you

    enhancing

    enabling

    envisioning - (I don't think that's a real word, but I like it!)

  16. #16
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    In the 12" sq , you have 12" in the length and 12" in the width. When you divided the 12 by 2 you go 6 , however you only divided one dimension. There are four 6' sq. in a 12" sq. Two across the top half and two across the bottom half.

  17. #17
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    I don't see any answer to any of the questions or suggestions raised. How can we give an informed answer without the facts.

  18. #18
    Super Member Greenheron's Avatar
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    Quote Originally Posted by bearisgray
    empowering is a good word - thank you

    enhancing

    enabling

    envisioning - (I don't think that's a real word, but I like it!)
    Of course envisioning is a real word. It's what we do when we look at fabric and SEE quilt.
    en·vi·sion (n-vzhn)
    tr.v. en·vi·sioned, en·vi·sion·ing, en·vi·sions
    To picture in the mind; imagine.
    The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
    :wink:

  19. #19
    Power Poster PaperPrincess's Avatar
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    And just to confuse things more, you need to remember to subtract the 1/2" seam allowance first, then divide by 2 then add the 1/2" back on...

  20. #20
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    this would have undoubtedly have happened to me :?:

  21. #21
    Super Member teacherbailey's Avatar
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    The formula for each piece is this: Subtract 1/2" from each dimension. Divide each dimension by 2. Add 1/2" to each dimension.

    Example: 8 1/2" x 4 1/2" rectangle to be made half size.

    8 1/2" - 1/2" = 8. Divide by 2 = 4. Add the 1/2" back = 4 1/2"

    4 1/2" - 1/2" = 4. Divide by 2 = 2. Add the 1/2" back = 2 1/2".

  22. #22
    Super Member CoventryUK's Avatar
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    Solution??? Try another pattern!!! T his is getting FAR too technical for me!!!!!!!!!!!!!!!!!!! :roll:

  23. #23
    Senior Member sarahrachel's Avatar
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    Oh I totally agree! me and algebra got along great most days, but basic math, not so much! I wanted to make a miller's crossing quilt, but I wanted 12 inch blocks, not 6 inch blocks, so instead of googling it to find the correct measurements, I just double everything. NOPE!! All my 9P on point pieces don't have points, and my pinwheel blocks have little borders on them. Good luck though, you may get it!

    here's half of it!
    Name:  Attachment-225014.jpe
Views: 50
Size:  80.6 KB

  24. #24
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    the 1/4" seam allowance also applies to each unit within the block.

    A finished 12" block which is not joined to other blocks is 12 1/2".

    Reduce finished 12" (not 12 1/2) to 6". But you have to add 1/4" to each component of the block and the outside seams.

    A triangle in a sqare would be plus 1/2" for the outside seams, no extra width-wise, but plus 3/8" plus 3/8" for both sides of the triangle height-wise. (triangle is pointing up or down)

    A pinwheel would be plus 1/2" outer SA plus 1/2" inner SA both directions, ditto a sq in a sq.

  25. #25
    Super Member sewwhat85's Avatar
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    i would have to agree with the subtract seam allowance divide by 2 then add seam allowance back .

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