Ripstop nylon and goose down were made for each other. A Karo Step quilt is a perfect design for a quality made down comforter. Easy enough to make following these simple instructions.
The reward is worth the effort.
Calculating the down
This is how to calculate the amount of down needed for a quilt.
The warmth of the quilt is related to the “loft” or thickness of the quilt.
Loft is determined by the “fill power” of the down as well as the space it is in. Here are some generally accepted values for loft:
50°F = 1″; 40°F = 1-1/2″; 30°F = 2″; 20°F = 2 -1/2″; 10°F = 3″; 0°F = 3-1/2″ and -10°F = 4″.
For this ‘queen’ sized 90″ x 90″ quilt, we will use a 2-1/2″ baffle. That is a baffle 3″ wide x 6″ long, sewn in place with a 1/4″ margin both sides which will give a 2-1/2″ space for the down.
Using 700 fill down:
90″ x 90″ x 2-1/2″ = total cubic inches.
total cubic inches ÷ 700 cubic inches per ounce = total ounces.
20,250 cubic inches ÷ 700 = 28.9 oz.
28.9 oz ÷ 16 = 1.81 pounds.
The Karo Step design benefits from being 30% “overstuffed” which helps to keep the down from shifting:
20,250 cubic inches x 1.30 = 26,325 cubic inches.
26,325 ÷ 700 = 37.60 oz
37.60 ÷ 16 = 2.35 pounds
That is the correct amount of 700 fill for this quilt.
So that is the calculation. Change the size of the quilt, the thickness of the quilt or use a different “fill” down and you can calculate the result.
The drawing above is for a 90″x 90″ quilt with a 10/6 pattern. It has 144 baffles. The 10/6 pattern is the best for this type of quilt.
For material use .67, .9, 1.1, 1.6, or 1.9 oz per square yard ripstop nylon, the choice is yours. Make sure the ripstop is ‘breathable’ and ‘calendered’ which makes it ‘downproof’.
The amount needed will be 11 yards total, 12 yards total if you cut the baffles from the same material instead of using mesh material.
The finished size of the quilt is 90″ x 90″ but there needs to be extra for hems so the size needed is 93″ x 93″ which will allow for hemming on all four sides.
Ripstop does not come in widths wide enough so each side of the quilt must be made of two pieces.
(93″ ÷ 2) + 1/4″ for a hem = 46-3/4″.
That would be (4) pieces cut 46-3/4″ wide x 93″ long.
Work with the material folded in half for ease of handling.
Cut it off at 93″ long. You need to use two metal straight edges when using the hot knife or you’ll burn your work surface.
Layout the folded side 1/2 of the 46-3/4″ or 23-3/8″. Layout the baffle material in 3″ wide strips. Luckily we got two strips out of this material’s width this time.
Make your cuts and then do this three more times to get all the material cut.
Made this setup to cut the baffles quickly. Stacked two strips cutting 4 baffles each cut.
Definitely use a hot knife, as a Karo Step quilt is not something that is readily repairable if a baffle cuts loose at a later time. One reason against mesh in my opinion.
Before you start sewing, set your machine to avoid problems as you work through the project.
Check the upper thread tension, lower thread tension and foot pressure on test pieces until the stitching is perfect. Set the stitch length to 8 stitches per inch.
Sorry about the pictures – black on black with black thread. We are using Schmetz Microtex needles in 70/10 and Gutermann Tera 80 thread. Gutermann Sew-All thread would work fine also.
Sew two of the sides together with a 1/4″ hem. Layout for the baffles that fall along the seam at this time and pin them in place.
Stitch with a straight stitch first, then stitch one more time using your zig-zag setting and you’ll be amazed at how well that comes together as a bound edge.
It will look like this on the finished side. A nice tight seam.
Start the layout working out from the centerlines making a 10″ pattern in both directions. Notice the baffles in place on the seam in this picture.
Make a 4″ x 4″ template and use it to mark a pattern for the start/stop points of the baffles. Any hard plastic sheet or stiff cardboard would work well.
Mark the entire 93″ x 93″ side of the quilt using a washable fabric pencil.
Sew all the baffles on the one side first. Use no pins, you can just hold the baffle in place setting it 1/4″ over the line and stitch away.
When sewing just move from baffle to baffle and cut the threads after each run of rows. Lock stitch the beginning and end of each baffle.
Check the integrity of each row when clipping threads off as going back is not an option with this design.
It makes no difference which side of the line the lip of the baffle is on as far as it being ‘C’ shaped or ‘Z’ shaped in assembly. Doesn’t matter.
Completing the quilt
With all the baffles sewn on one side and everything checked it’s time to start stitching the other side on.
Layout the other side of the quilt with the 10″ x 10″ pattern starting from the centerlines and working out. Mark all of the start/stop points for the baffles. Make sure the center seams are running in the same direction before beginning to sew.
Very simply the baffles will be sewn on starting at one edge and working across the quilt in rows to the other side.
One row of inline baffles will be sewn in a row and the next set are sewn with the baffles at 90° to the last row.
Here’s the trick: when doing the 90° row slide the entire quilt onto the machine bed like a sausage maker pushes casings onto a stuffing horn. That way after a baffle is sewn in, it exits left and the next one is ready to be sewn. It will go very smoothly and you will not be stitching through layers of crowded material by mistake.
Finish that row then stitch the next straight row then stitch the next 90° row and repeat until all the baffles are stitched in place.
As before check the integrity of each row before moving on.
Now for hemming the sides. First hem the two sides parallel to the seam in the quilt.
Mark a line 2″ from the edge and mark a spot in the middle that will not be sewn.
Mark this opening 30″ wide. That opening is to stuff the quilt with the down later.
Fold the side in once and then twice to the 2″ line and pin making about an 11/16″ hem.
The arrow is for a bar tack, one on each side of the opening, so the quilt can be opened in the future and not have the whole side come apart.
Bar tack the two places.
Sew the hem up to the bar tacks from each corner with two rows of stitches. Pin the opening closed temporarily with safety pins. Do both sides.
Hem the remaining two sides full length like before using a 2″ guideline effectively making a drawstring sleeve.
Bar tack a loop of 3/8″ ribbon x 4″ long doubled over in the center at the seam.
String the sleeve with a piece of No. 36 nylon bank line for a drawstring. Tie stopper knots at each end and hand stitch the sleeve to restrict the knots from pulling into the sleeve. Do both sides.
The drawstring allows the quilt to be ‘drawn up’ at the bottom to make a foot box for the feet. An especially nice option in colder weather.
The bags of down came shrink wrapped with the down in a cloth bag about the size of a small pillow.
Tape down the opening to the table to help steady the quilt.
Basically holding the bag close to the quilt – grab fistfuls of down and push them gently into all the chambers you can reach.
It is really easy to do and very little got away after stuffing the whole bag. Gather up the escapees and stuff them in.
Pin the opening and stitch it closed. Do both sides.
After both sides are finished shake the quilt vigorously in every direction to distribute the down.
That is the beauty of the Karo Step design now and in the future. You can always redistribute the down by just shaking it up.