Jerry Quilt Idea

[Bill Townsend]

I made a 3/4 tapered Underquilt using Jerry's idea of half radius sewn through baffles.
The taper added a little challenge to things but I think will actually be a bonus in that the down cannot shift too much in the cone shaped tubes.

A little fussy getting it started but overall WAY easier and so far good results. Layout was easy after making a few "tests" on Google Sketch-up. A south facing patio door was a huge help as well in getting everything pinned together.

I went with a 2.5" design loft, so 5" baffles. I tapered them to 2.5" at the end but kept the same height, so the end baffles are more like 2/3rds of a circle.

I "lost" about 1" or so in length on each side to close the channels, the down tapers from full height to zero there. I just bunched the fabric evenly and sewed, I think this leads to more room than doing a true dart or tuck to gather the fabric.

Laying on a table there is about a 1" wide by 1" divot. As long as you keep baffles to towards the body though at worst you could say you have 1.5" of loft at the seams, realistically I think you are still trapping conditioned air there.

If you curve it at all (like it would be in an UQ or on your body) then these spaces close up- leaving you with a differential cut baffle with no headaches to calculate. No good way to measure it, but you may even pick up a little loft as well per the old eyeball tape.

Overstuff-
Actual overstuff is higher than design. I used the area of the quilt x loft /fill * 130% for overstuff. This worked out to 22.8 grams per baffle. I rounded to 24 for the hell of it, and with a bit of down floating around or sticking to my hands I measured 25 grams. Doesn't sound like much, but that little here and there turned my actual overstuff into 42% on this smaller quilt.

It was only tumbled for a bit, needs a bit more clump busting from stuffing.

How warm you want to call 2.5" of down is up to you. ;)

35 at head, 17.5 at calf- 56" long- 244 grams before final channels and attachments. Only 11 grams off calculations (1.5g times seven baffles is 10.5 of it though, not shabby)! Forgive my broken elbow.

Now to sort out how to attach this thing.

Thanks Jerry!

[JCH]

THAT looks damned sweet. I want!

[Daryl and Daryl]

The concept and your execution of same are very appealing. Really looking forward to your feedback when it hits the road.

[Jerry Adams]

Very nice!

Great – I suckered someone else into doing this : )

I have some fabric, down, and zipper. I'm making a vest.

[Sam Haraldson]

Beautiful work, Bill.

[Jerry Adams]

Couple questions

I assumed you used the down from your previous project? It looks like you've fixed the problem with baffles that have places with voids?

I assume you used Argon67 fabric? After a few nights it would be interesting to hear how much down leaked.

The top side fabric is 5 inch wide baffles?

The bottom side fabric is 7.85 inch (or 7 7/8 inch) wide baffles?

How much did the final quilt weigh? How much did the fabric weigh? If there's anything besides down and fabric, what did it weigh?

Is your quilt 35" wide by 56" long? Doesn't seem like 35" is wide enough. You could always just add some baffles and sew them on and it would be almost the same as if you had done it as one piece.

How much did the total down weigh? I think maybe it was 6 ounces. (That seems low?).

Now if you did 42% overstuff, and 30% is the actual optimum (which was a wag, but anyway…), then you did 12% extra overstuff. According to my interpretation of Richard and my data, if you overstuff, you lose half the warmth. Total down is 6 ounces. total down is 142% "stuff", 12% is exessive, so 12%/142% = 0.08. You only get half the warmth so half of that is "wasted". That would be 0.04. 0.04 of 6 ounces is 0.5 ounces. So, you have "squandered" half an ounce, but by being more overstuffed the baffles will be better filled in the case the down got a little damp or some leaked out over time or if you screwed up and accidentally put a little less down in a baffle or whatever… So, doing 42% overstuff instead of 30% sounds good to me.

[todd]

Jerry,

This quilt is an underquilt for a hammock, so the narrow width would go at the foot end. Many use a tapered design nowadays. Saves weight, of course. But ya better be a still sleeper!

Bill,

You did a great job!!! Thanks for good pics.

[Jerry Adams]

ahhh… I see now…

[Bill Townsend]

Yar, the down is recycled. As far as the full baffles-
I think I am onto something with the overstuff insights on fill area in traditional baffle shapes. I saved the first shell and may try re-stuffing it.

This baffle shape is already close enough to a circle anyway and the math was within 5% that it worked out pretty well on it's own.

DUHHH!- So, uhm, yeah… I was just using my regular 1g digital kitchen scale, likely a contributing factor. I bought a 1/10 gram scale for this project and eliminated that variable.

Argon 67- Yes.
Well, I wasn't concerned at all until you mentioned it in the other post. I haven't heard many complaints. I can see feathers poking through, but in 850+ they are very minimal to start. I haven't heard other complaints, but I am not a big down guy either.
FWIW- I use the old tennis ball trick to fluff. 4 clean tennis balls in a regular home dryer on air fluff. So far, in the dryer on and off for an hour or so. My four year old played with it for a half hour, and it's been dragged out for fitting a few times. Not a feather lost that I have noticed.

5" baffle- 7 7/8" top/head
2.5" baffle- 6 15/16" bottom/foot
I used a 1" seam allowance on everything, and pinned the whole thing together first. As you may guess- the two pieces are about a 1/2" difference in length when laid out.
I pinned the head and foot first, then the centers of each baffle, and smoothed out from there to "loose" the difference in the length.

Size- You are 100% right- It would be easy to add a baffle.
This is a top secret project for a new UQ design. Most hammock quilts are 40-50" wide and hung from the ends. The top secret part is how to attach mine effectively, it's so top secret I haven't figured it out.

However, even if that is a bust- my narrow bridge hammock is 36" at the shoulders and this will fit perfect on that. Attachment is likely as easy as a few inches of shock cord and four mitten hooks on the bridge.

Weight-
Nothing is added yet- I figured you'd ask so I stopped to check. I lost the shell weight I wrote down but I recall it being grams away from my estimate of 2.55oz.
Finished weight of the quilt- 244 grams. So almost dead on 6oz of fill.

Overstuff reality-
I used the insulated area of the base shell (not including seam allowance). 10.2 sf.
10.2 x 144 x 2.5 /850 fill * 1.3= 5.616oz
5.616 * 28.5 = 160.06 divided by seven baffles= 22.86g per baffle.

NOW- I should have just rounded to 23g. I rounded to 24 for no very good reason other than it's a few grams.

ALSO- with new scale handy I could clearly see how little down 1/2 a gram is. My stuffing operation actually went very well but figuring a few clingers or lost clumps in stuffing I WEIGHED 25 g.

So perfect 30% was 22.86.
I added 1.14g per baffle for no good reason
I added 1g per baffle for potential stuffing problems.
Now- 2.14 g per baffle times seven baffles is 15g
15g brings me up to 6 oz total fill and the 42% actual overstuff.

Hold your horses though-
This is a very small quilt. If this was one pound of fill, those 15 grams I used still seem like decent sense but would produce nowhere near the change in OS %. Adding a gram (pinch) of fill per baffle makes sense for stuffing error. For MYOG rounding up to the next gram makes some sense too I think- but just keep the 2g or so per baffle in perspective, deceptive result on this one.

That said, 40% on this design may be a safer number overall. Especially if you aren't chasing grams like me, that's an easy insurance policy as the design gets tinkered with. If for no other reason than the baffles are so long. I didn't try it, but your break in the middle idea doesn't seem too bad either, on this one, I figured the tapered baffle will help some to prevent shifting too much- but we'll see.

They are clearly full, but the baffles don't seem to be bursting at the seams either, so even for me, I think I will use 35% and the rounding/extra gram per baffle route if/when I scale this up. I really pack the down hard like a snowball, part of the reason I lost almost none- but it makes the clump busting process a bit slow. I'll have to let the down recover or beat it in the dryer more before I could say for sure. I may even run it on a few cycles just to see if any down pops on the argon too.

[Jerry Adams]

thanks, sorry so many engineer questions : ) I don't have that much experience with down either so profitting from your experience.

I just busted up wads by slapping with my hand. Held it up to light to see where any voids were….

The real question isn't so much how much down you lose in the dryer, but how much you lose in real use. Every morning I get up in my Nobul bag, there are maybe 100 down feathers. Now there are a zillion feathers in the bag total, so if it loses 100 per night, it will probably take forever for it to make any difference. Plus, after a year, it seems like there are fewer feathers leaking.

Maybe feathers leak more easily than down. So not really that big a deal.

Hmmm, maybe you take lower fill down, put it in Nobul bag, manipulate, you'll end up with higher fill down… I know, "quit thinking so much"

5 inch baffle, for semi-circle you want the other side to be 5 * pi/2 – very close to your 7 7/8". 2.5 inches – you did 6 15/16 inch but semicircle would be 3.9 inch. How did that work? I don't know that a semicircle is best…

[Bill Townsend]

Ask around here as I never got my hands on any, but I did hear of some issues with Nobul. Argon or M50 have generally been safe as far as I know. I do personally think that the higher fill downs loose less. In days past it's always been feathers (shafts) that have popped out for me.

My HS geometry is showing, I better pull my pants up.

I used sketchup, basically set the width at half- for an even taper, but kept the height at 2.5" to maintain the loft. Why it works, not sure, but seems to be working, talking it over with you likely less fabric could be used if you did a 1.25" radius and simply added the 1.25" to the sides? That would be 6 7/16" instead of 6 15/16" Not a ton different but 1/2" over seven baffles adds up.

It seems to be lofting almost dead level across the board. I also observe the same "flat side" deflection as you- 1/8" to a 1/4".

Since I calculated on area x loft- it likely didn't matter.
I considered calculating by cross section but I didn't like the results of that math very much. Likely I did it wrong- I just did area at each end and averaged it then multiplied by length. I am guessing there is more to that formula than my quick guess.

[Bill Townsend]

I jury rigged the quilt to my bridge-
You lose a little loft, but that's partially design related.

Otherwise- pretty windy nasty wet evening. Low 22, windchills in single digits. Beatup 15 degree down bag up top and foam pad at foot area. Hats and baselayer worn.

Quilt worked fine- had a few drafts when very windy that caused cold spots- but again- that's more a symptom of my jury rigged setup than the quilt itself.

Bottom line- the base premise is pretty good. I need to work on shape and perhaps even varied baffle thicknesses for an UQ. Maybe even a horizontal baffle at each end to close things up better.

I would not hesitate to continue to pursue this design. I think it's likely that a minor reduction in design loft should be accounted for, say design and build 2.25" to achieve 2" but this is no different than any other design.

I also think that as long as you design the "flat" side at the size you want, it eliminates any fiddling with differential cut calculations as well. So construction and design are simplified even further.

I'll be ordering up some down soon to make some more test shells/designs.

[todd]

Great to hear, Bill!

I think this will end up (thanks to you and Jerry doing so much of the legwork!) being the easiest UQ to construct.

An insulated draft tube (like you refer to) will do wonders.

[Steve Chan]

I was thinking about this idea and wondered about a modification to this. It would be heavier, but it might be worth it due to the ease of construction and the additional water resistance.

What if, for the side that has the semi-circular baffles, you used the .5oz no-seeum mesh that RBTR sells. It is fairly light, and it may actually do a good job of preventing down migration.

Then, you have another layer on top of the noseeum baffles for an outer shell that is only attached at the perimeter. This would create an air gap, to compensate somewhat for the sewn through baffles and also provide an outer shell without any sewn seams that need to be sealed for water resistance.

So you would have sewn through baffles on the inner shell, and a smooth, seamless outer shell that covers up the noseeum baffles underneath. If there is any down migration through the noseeum, it is all trapped between the noseeum and the outer shell anyway.

Its more work then the sewn through semi-circular baffles (but not much more work) but should provide some more water resistance. Does it make any sense to try this?

 

[Jerry Adams]

I think I see what you’re saying, I suppose that would work

If the semi circular baffles face your body, then the sewn through baffle space is enclosed by your body so you don’t need a fabric covering it.

Whether you have this design or conventional, the rows of stitching are not as waterproof or windproof as if it was just a smooth fabric like you’re saying which would be good

I wonder how this has worked for Bill after a year

A row of my stitching started to fail which I just re-sewed.  With a conventional design, one side is hidden so it’s difficult to re-sew a row of stitches.

My only problem is my fabric isn’t 100% down-proof, so I lose a lot of down, but it’s a tiny fraction so not a big deal.

 

[Steve Chan]

It occurs to me that the gap between the outer shell and the noseeum baffle material might cause water vapor to condense on the inner surface of the outer shell instead of inside the down. Not sure it would be a huge benefit since its still trapped inside the quilt and would tend to drip back onto the no-seeum.

[Author]

Posts