Differential baffles

[FreeTheWeasel]

Greetings,

I need a fourth quilt to round out my set. I currently own a No Sniveller, a 2" Red River Gorge, and a 3" Red River Gorge. Believe it or not, I actually enjoyed the long, agonizing process of making my two quilts and I'm ready to do it again.

I'd like to attempt a differential baffle quilt. In this thread Grizz and Schneiderlein went math crazy and the conclusion was that Schneiderlein decided to make each bottom pannel 2" wider than the top. Does that seem correct? All my current quilts have the baffles run side to side. Clearly, I couldn't add 2" to each baffle in the head-foot orientation. That would add an additional 1.6 feet of fabric! Side to side, yes, i could see it but is that enough? Does anyone have concise plans for a differential baffle design?

Secondly, what would you suggest be done with the no-seeum mesh inside? Does that need to be cut with a radius or can you simply cut it in a rectangle and let the mesh buckle on the inner, shorter stitch?

Thanks

FreeTheWeasel

[Just Jeff]

You could let the mesh buckle, but that means you're carrying extra weight.

If you don't want to cut the mesh rounded, like a radial, you could approximate it with two 45 degree corners on each side. For example, make the baffles going widthwise across the body. If you were laying under the quilt, on the far left side the baffle would go straight up (90 degree angle to the floor) for 4", then a 45 degree angle for another 4", then 34" across the top of your body, then 4" diagonal section and then the final 4" would be vertical. That would give you a 50" wide quilt that wouldn't allow the baffles to buckle, so the loft would be much more consistent throughout.

And the inside DWR panel would me much narrower than the outer panel...guesstimating ~8" narrower if the baffles are 2" high.

See if I can draw this...ignore the dots.

...._______
.../.______.\
././..........\.\
|.|...........|.|

[Youngblood]

Greetings,

I need a fourth quilt to round out my set. I currently own a No Sniveller, a 2" Red River Gorge, and a 3" Red River Gorge. Believe it or not, I actually enjoyed the long, agonizing process of making my two quilts and I'm ready to do it again.

I'd like to attempt a differential baffle quilt. In this thread Grizz and Schneiderlein went math crazy and the conclusion was that Schneiderlein decided to make each bottom pannel 2" wider than the top. Does that seem correct? All my current quilts have the baffles run side to side. Clearly, I couldn't add 2" to each baffle in the head-foot orientation. That would add an additional 1.6 feet of fabric! Side to side, yes, i could see it but is that enough? Does anyone have concise plans for a differential baffle design?

Secondly, what would you suggest be done with the no-seeum mesh inside? Does that need to be cut with a radius or can you simply cut it in a rectangle and let the mesh buckle on the inner, shorter stitch?

Thanks

FreeTheWeasel

Here are a couple of links where the fundamentals of differential quilts are discussed http://www.hammockforums.net/forum/s...tial#post54997 http://www.hammockforums.net/forum/s...tial#post50893 .

You can create a differential shape along the width, the length or both the length and the width. The two methods I've used are shaping the baffles themselves (cutting them on a curve or using multiple darts to simulate a curve) and using radially spaced baffles. To get differential shaping along both the length and width I use both techniques.

A properly differentially shaped underquilt with an adequate suspension system, like the SnugFit, will significantly out perform a flat underquilt.

[Peter_pan]

Greetings,

I need a fourth quilt to round out my set. I currently own a No Sniveller, a 2" Red River Gorge, and a 3" Red River Gorge. Believe it or not, I actually enjoyed the long, agonizing process of making my two quilts and I'm ready to do it again.

I'd like to attempt a differential baffle quilt. In this thread Grizz and Schneiderlein went math crazy and the conclusion was that Schneiderlein decided to make each bottom pannel 2" wider than the top. Does that seem correct? All my current quilts have the baffles run side to side. Clearly, I couldn't add 2" to each baffle in the head-foot orientation. That would add an additional 1.6 feet of fabric! Side to side, yes, i could see it but is that enough? Does anyone have concise plans for a differential baffle design?

Secondly, what would you suggest be done with the no-seeum mesh inside? Does that need to be cut with a radius or can you simply cut it in a rectangle and let the mesh buckle on the inner, shorter stitch?

Thanks

FreeTheWeasel

FTW,

Good luck with your project....

If you decide the "enjoyment of the project" is too much time and uncertainty.... the warmest differential cut quilt, the Mt Washington is currently on sale below $300... zero degree capability...http://www.jacksrbetter.com/index_fi...Washington.htm

Pan

[Schneiderlein]

Greetings,

I need a fourth quilt to round out my set. I currently own a No Sniveller, a 2" Red River Gorge, and a 3" Red River Gorge. Believe it or not, I actually enjoyed the long, agonizing process of making my two quilts and I'm ready to do it again.

I'd like to attempt a differential baffle quilt. In this thread Grizz and Schneiderlein went math crazy and the conclusion was that Schneiderlein decided to make each bottom pannel 2" wider than the top. Does that seem correct? All my current quilts have the baffles run side to side. Clearly, I couldn't add 2" to each baffle in the head-foot orientation. That would add an additional 1.6 feet of fabric! Side to side, yes, i could see it but is that enough? Does anyone have concise plans for a differential baffle design?

Secondly, what would you suggest be done with the no-seeum mesh inside? Does that need to be cut with a radius or can you simply cut it in a rectangle and let the mesh buckle on the inner, shorter stitch?

Thanks

FreeTheWeasel

The quilt I made is a 3/4-UQ with coffin-shaped panels. If you hold it up at two ends, it naturally takes on the shape of a hammock. I have a pdf file somewhere for how the panels are cut. I can dig it up when I return from Germany next week if you are interested.

The noseeum baffles are not just rectangles, they are curved.

I made this quilt mainly to satisfy my curiosity of whether I could shape a quilt using multiple panels. The quilt works great, but I am not sure if I would make another one like it. Using multiple panels adds quite a bit of weight in the seams. The next one I make will probably use two solid panels with the baffles running along the short direction of the quilt. The trickiest part in dealing with curved noseeum baffles is controlling the stretch while sewing them on. That's why I think the shorter you keep them, the better off you are.

If you need help figuring out the panel and baffle sizes, I wrote some small scripts when I made my quilt to ensure the seam lengths are equal. I'd be happy to dig them up and run the numbers for you.

[te-wa]

The two methods I've used are shaping the baffles themselves (cutting them on a curve or using multiple darts to simulate a curve) and using radially spaced baffles.

thanks for reinforcing my idea about shaped baffles... fwiw, I found that baffles running the length of the hammock suffer far less compression under body than that of "horizontal" ones. Of course, to keep down shift to a minimum, horizontal baffles with radial cut mesh is the ticket. my uq simply has an additional inch of fabric on the outer shell, per chamber. Then i folded and sewed the edges (head and foot ends, respectively) with darts to take up the slack. very little loss of loft this way. (much less than that of a flat baffle, forced to curve under your weight)

[warbonnetguy]

a hammock curves far more side to side than it does lengthwise. it makes sense to have the baffels running lengthwise and have the baffles differentially spaced on each shell. you could give them a slight curve lengthwise, but as long as the shells are differentially cut in bothy directions, i doubt a baffle that buckles slightly will have any ill effect (it's not going to cause air gaps in your quilt i don't think) you are looking at shaving a tiny bit of weight off of the netting by making it curved, but it's the differential cut of the shell that allows the down to fully loft, that is the main thing. now since the quilt curves so much from side to side, using a straight baffle that direction would indeed cause severe buckeling, and i'm not sure what that would do, but if you just go lengthwise with the baffles you can fit this severe curve simply by using a differential spacing of the baffle seams to make it curve.

youngblood,

would you say placing pleats/darts along an edge really only effects the edge?

it makes sense to me that doing this simply fits one larger perimeter to a smaller perimeter. and all the pleats that ive done in quilts flatten back out only a few inches into the interior of the quilt essentially making them act flat (not regarding the diff cut shells). the experience i have had shaping a flat ccf to the dual curve of a hammock has taught me that simply cutting out a triangle (or making a pleat if done to fabric) doesn't really give a 3d shape if it is done to just to the edge. in other words, to really make a ccf pad fully contour to the shape of the hammock, the cut needs to go all the way to the center of the pad, and to truly make a sheet of fabric contour the hammock without buckeling, you would have to stitch the darts flat all the way into the center of the quilt, least they just flatten out on their own and then the fabric buckles naturally like flat fabric curved in two directions does anyway.

i don't see how darts at the edge "contour" anything but the edge if they do not continue into the interior. does the sf have darts like the swt that are sewn all the way across or are they like pleats around the edge of the quilt to fit one shell to the other, i was under the impression that they were merely pleats alonmg the edge rather than darts like the swt has that are sewn all the way across.

also, are there pleats in the smaller shell piece of the sf or just in the larger piece?

[Youngblood]

thanks for reinforcing my idea about shaped baffles... fwiw, I found that baffles running the length of the hammock suffer far less compression under body than that of "horizontal" ones. Of course, to keep down shift to a minimum, horizontal baffles with radial cut mesh is the ticket. my uq simply has an additional inch of fabric on the outer shell, per chamber. Then i folded and sewed the edges (head and foot ends, respectively) with darts to take up the slack. very little loss of loft this way. (much less than that of a flat baffle, forced to curve under your weight)

Down shift is a little trickier with underquilts than with top quilts because underquilts can hang at extreme angles. I used what I called a zero down migration fill to handle that-- it is basically a calculated 'over fill'. It is calculated based on baffle height and baffle spacing.

When the underquilt is hanging freely on an unoccupied hammock that doesn't have some type of spreader bars or pullouts, there isn't anything forcing the baffled chambers into the basically rectangular cross section that it is designed to be. I look at it as the down is expanding outward in all directions, just like a pressurized air mat. The most efficient shape to maximize area for a given perimeter, or circumference, is a circle and that is what each chamber would go to if it was pressurized and didn't have constraints of adjacent chambers. When you look at it that way you understand better the importance of baffle spacing. Baffle spacing is extremely important is controlling down migration and in how tight a radius, or curve, you can follow when you use radial spaced baffles to create a differential shape.

Curved baffles are different in regards to how well they can follow a tight radius since they are continuous in nature instead of discrete. Radial spaced baffles have two design elements for its curvature: the radius it is designed for and the baffle spacing picked to achieve it. If the baffle spacing is too large in comparison to the radius of the curve it is trying to follow, it can't follow it well.

[Youngblood]

Brandon,

Working our differential shaping for sheet insulation is a little different than working out differential shaping for loose filled insulation. You have different constraints and different things to work with. In both cases you do have the situation where the inner surface is shorter or has less area than the outer surface and you do have to address that so that it all fits together. Pleats around the edges will do that for both cases as will curved baffles. And you can simulate a curve with enough well placed pleats.

The SnugFit is an unusually sophisticated design. It has variable height curved baffles that have variable radial spacing, lots of darts and a unique suspension system. It covers a large surface area to accommodate a wide range of sleeping positions. The large surface area and the desire to design out the typical troubling cold spot under the tush area lead to a lot of the sophistication.

[warbonnetguy]

youngblood,
I was mainly referring to how the "inner shell" fits to the hammock, this is the same no matter what hangs below it. In doing my design i would actually cut the inner shell (the one against the hammock) and add the suspension to that and hang it. This way i could directly see any spots that weren't snug. I found (for a torso shell) that the flat piece can fit perfectly snug to the user's underside (if shaped and tensioned properly), and the only slight looseness i was getting was along the top of the arms near the edge of the quilt where the user's body wasn't pressing against the hammock (kinda like how a ccf doesn't buckle under you, but only where it exits your body). A flat shape can definately fit flush and snug to the bottom of the hammock. Look at the bottom of an end gathered hammock itself, it's a flat shape, but there aren't even so much as wrinkles under the part where the torso,butt, and shoulders lie. The same can be done with a flat shape uq if the right shape and tensioning are used. This i think, is the key.

Now the air gap under the knee area ridge is a different story, maybe this is what you were referring to as the cold spot under the butt of a flat quilt.

You never answered my question about the darts in the sf. When you call them "darts" are you referring to darts as in the swt that are sewn across the width of the fabric, or are they like pleats just along the edge?

I don't see how a slightly buckled baffle (running end to end) will negatively effect performance of the uq if the inner shell (flat or contoured) is flush/snug to the bottom of the hammock AND the inside of the quilt is completely full of down and not compressed. Simply changing positions in the hammock can change the degree of curve of the bottom of the hammock, so i don't see how having baffles with a slight "fixed" curve can keep the baffles from buckeling, as the exact curveature of the bottom of the hammock is dependent on body position, weight of hammock fabric relative to body weight ect. Slightly buckled baffles or not, if the inner shell is snug to the bottom of the hammock and the there are no air pockets in the uq itself, there should be no loss of effiency, and i don't see a straight cut netting being forced into a slight curve and buckeling slightly in the process causing air gaps inside quilt, and certainly wouldn't effect how the shell fits to the hammock.