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Fold calculation roman blind

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  • Fold calculation roman blind

    Help. I want to make a roman blind with folds which are an equal distance from one another (cascade I think it is called). I tried Merrick and Day cascade formula but it did not work out at all. The bottom hem/ batten section was too long, the next 3 folds were the same length and the top one too short. I measured carefully. I cannot work out what I did wrong.

    I have some which were made for me but cannot work out how to do it mathmatically.
    Does anyone know how to work out these measurements?

  • #2
    Re: Fold calculation roman blind

    Do you mean a roman where the folds pull up behind each other when raised? Have you checked this post which has details roman calculations.

    Could you post the dimensions of the blind you are working with?

    sigpic Simply Sewing


    • #3
      Re: Fold calculation roman blind

      I want the edge of the bottom hem and each fold to sit 2 or 3 cm below the next one up rather than having them stacked behind.
      I was working on a blind 133 w
      163.5 finished length.
      In the Merrick and Day there is a calculation for cascade fold which i thought I had followed but it didnt work out.
      The first time I did it the bottom hem (with batten) hung exactly behind the bottom fold and the top fold was too short.
      The second time I did a blind I re read the instructions realised I hadnt done it quite right ,made a different calculation but the folding was worse. The bottom hem is much too long and the next three folds sit exactly behind one another while the top fold sits much higher up.
      I took off 5 cm for wodden batten heading before I made fold calculations.
      I have just got a commission to make a blind using very expensive material and am in a total panic.


      • #4
        Re: Fold calculation roman blind

        Hello there

        I also had an awful job with Cascade Romans, it nearly drove me mad. Eventually, after hours of working and re-working the spaces, I read somewhere about using tapes. These are measured shorter than the space between the rods, and the way I worked it out was: Measure the tape to the actual length of the blind drop, and divided by the number of rod spaces to fit the unfinished length of your blind ie, the tapes govern the 'cascade ' of the blind so the longer the blind the deeper the cascade will be. I used clear tape, and stitched it to either side of the rod pockets, and it looks really neat from the wrong side.

        Make sure you do your final press before attaching the tapes as you will only be able to run a steamer over them after. This is a permanent cascade.

        I hope this helps, they really are infuriating.

        If you find a better method, please let us all know.

        Kind regards, Jessie
        I'd rather be sewing!


        • #5
          Re: Fold calculation roman blind

          Jessie, I think you are talking about hobbled blinds - blinds that have folds in when down - not cascade blinds which, when down are flat, but when raised, there is a space between each fold showing. Is that right?

          I'm sorry I can't help with the cascase blind as I've never made one.
          Kind regards
          Pen Harrison
          Colly Brook Fine Furnishings


          • #6
            Re: Fold calculation roman blind

            Dead right Pen!

            My inexperience is showing! I now need to know what a cascade blind looks like as I thought that they were one and the same, just the difference in American/English terminology.

            I really must read more......

            I'd rather be sewing!


            • #7
              Re: Fold calculation roman blind

              They are normal roman blinds flat when down and pulled up sit in flatish folds. how the folds sit is just the design. some stack up one under another and let in a lot of light but if you want more fabric showen the cascade method is good. Hope someone out there knows the answer!


              • #8
                Cascading blind



                [center:2kbe6jt7]This explanation does not allow for any seam allowance required for rod pockets[/center:2kbe6jt7]

                A section is the space between rod pockets. This calculation will give a 5cm cascade, 2.5cm stepping.

                Finished drop - 163.5cm I am assuming a head-rail of 9cm. Deduct this from the finished drop and calculate pleating as normal.

                163.5 minus 9 = 155.5cm.

                155.5 divide 9 = 17.3cm, this will give 4 folds (rod pockets) and 9 sections. Each full fold counts as 2 sections, the bottom section counts a 1 as it does not fold.

                You now need to decide the cascade - I have assumed a 5cm cascade. YOU DO NOT ADD A CASCADE AMOUNT TO THE TOP SECTION...

                9 sections, deduct 2 as we don't add to the top section, this leaves 7 sections.

                Cascade amount is 5cm multiply this by the 7 sections - This gives 35cm, this is the cascading amount. NB. Add a double cascade amount to the bottom. Making a total cascade figure of 40cm

                Finished drop 163.5cm minus 9cm head-rail minus 40cm cascade amount = 114.5cm divide this by the total sections which is 9 = 12.72cm.. Round up to 12.75cm

                All sections will be 2 x 12.75cm with the exception of the bottom section, this will be 12.75 as it does not have a fold. We now need to add the cascading amount back on.. Do not add to the top section.

                Top to bottom:

                Head rail: 9cm

                Top section 25.5cm (2 x 12.75)

                Second section 25cm plus 5 cascade = 30.5cm

                Third section 30cm plus 5cm cascade = 35.5cm

                Fourth section 35cm plus 5cm cascade = 40.5cm

                Bottom section, half the first section 12.75cm plus double cascade 10cm = 22.75cm

                This is not millimetre perfect and would need to be adjusted to suit the chosen head-rail - This calculation uses 163.75cm of fabric, I'll leave you to adjust if you want to. I'd suggest you make a sample first with a old piece of fabric.

                Hope this makes sense!

                MyDecozo Admin


                • #9
                  Re: Fold calculation roman blind

                  I have also seen this type of cascade blind called a staggered roman.

                  Just for reference, a hobbled roman has the same amount of extra fabric added to every pleat. This means that, even when the blind is completely lowered, the extra fabric falls into tailored folds covering the place where the horizontal rod pockets are. The tapes on the back hold the blind at the correct drop while leaving the excess fabric in even folds.

                  [attachment=0:u6qbflgb]hobbled roman.jpg[/attachment:u6qbflgb]

                  sigpic Simply Sewing


                  • #10
                    Re: Fold calculation roman blind

                    Many thanks. I just made it up with a piece of material and it worked.
                    Just so that I can use it in future not quite sure why each time you went from 25 -30-35. are you doubling and trebling the cascade?
                    I have also discovered that in the rotary chain kit the top ring is 2 cm the middle ones 1 cm and 2 cm.
                    I am working on a blind 142 finished length with 4 cm heading. This has thrown me.
                    Any idead how to calculate this. I am now brain


                    • #11
                      Re: Fold calculation roman blind

                      Each lower section has to be bigger than the one above in order to continue the stepping - If you add 5cm to the 1st section, the section below will need 10cm in order to continue the cascade down. With regards the header, I'd allow more than the deepest measurement of the track, this will allow for the rings and rod stacking as the blind is pulled up. 8/9cm is safe. Don't forget I didn't allow seam allowances for rod pockets.


                      I have also discovered that in the rotary chain kit the top ring is 2 cm the middle ones 1 cm and 2 cm. I am working on a blind 142 finished length with 4 cm heading. This has thrown me. Any idea how to calculate this. I am now brain
                      I'm not quite sure what you mean and will need more information.

                      Have you registered your business yet?


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