DIY Differential Cut UQ Calculator

[genixia]

I used Boston's modified Catsplat when building my quilt ( Look what just arrived ). It made my life so easy, thanks!

[Bushwhacker]

Thanks CatSplat!!!

I do have a few questions though - How would one determine what max Chamber height to use?

Also, what would be the optimal overstuff? Does that depend on fabric weight at all?

[CountryRoads]

Don't think CatSplat is following this thread anymore.

I'll start a thread of my own about this at some point, but I'm making this underquilt right now to the exact specs that the speadsheet is set to. I did some calculations on the amount of sewing involved: 56.7 yards, that's 170 ft, or 2,040 inches!!! Ridiculous!! I probably have 30 or so yards if stitching to do still. If I weren't this deep into it, I'd buy the darn UQ!

[Bushwhacker]

Don't think CatSplat is following this thread anymore.

I'll start a thread of my own about this at some point, but I'm making this underquilt right now to the exact specs that the speadsheet is set to. I did some calculations on the amount of sewing involved: 56.7 yards, that's 170 ft, or 2,040 inches!!! Ridiculous!! I probably have 30 or so yards if stitching to do still. If I weren't this deep into it, I'd buy the darn UQ!

Thanks for still hanging around (this thread - and responding)!
You don't have a sewing machine?

[CountryRoads]

Thanks for still hanging around (this thread - and responding)!
You don't have a sewing machine?

I think this thread is really valuable, so happy to keep it alive.

What gave you the idea that I don't have a sewing machine? I do. I've made most of my own gear. And I'm nearly half way through sewing the underquilt. I can't believe how much sewing it is!

[Boston]

Thanks CatSplat!!!

I do have a few questions though - How would one determine what max Chamber height to use?

Some advice you'll find on here says your chamber height should be 0.5" to 1" taller than baffle height. When I designed my UQ I worked around an estimated temp rating based on the Jardine formula. I made my baffles 0.5" shorter than chamber height.

What I've noticed is even hung unweighed, the chambers on the underside of the quilt are tight, while the sides are loose. Thus the bottom chamber are at design loft, or possibly slightly compressed, while the side chambers are actually showing MORE loft than design. So theoretically the side chambers are insulating more than the bottom chambers.

Playing with the calculator you can see the differential between liner fabric and shell fabric is mostly based on your ratio of baffle height to chamber height parameters. If they are the same, the differential is about 0.5". I am a cold sleeper, and right now I think my quilt doesn't quite hit my temp target, although I'm still testing.

The next quilt I make I am going to keep my baffle height 0.5" lower than desired loft (chamber height), but I'm going to adjust the differential. Right now I am thinking the 2 chamber's on each long edge will only have 0.5" differential, and the remaining 5 will have a 1" differential.

Also, what would be the optimal overstuff? Does that depend on fabric weight at all?

Usually 20-30%. I'd work within that range to make a nice even number for fill weight that you can easily measure.

[Bushwhacker]

I think this thread is really valuable, so happy to keep it alive.

What gave you the idea that I don't have a sewing machine? I do. I've made most of my own gear. And I'm nearly half way through sewing the underquilt. I can't believe how much sewing it is!

Well even at conservative speed of 1/2 yard per minute that should only take about 2 hours. Granted there are stops to attend to the fabric and such, but that's about 2 movies worth of sewing. You could watch gone with the wind and be done! Or any other classic you've seen a million times and has a great soundtrack. Of course I never sewed anything with feathers yet, so my timing may be inaccurate (and I sincerely apologise if that's the case), but I have far too many memories of sewing thick leather jackets by hand or even sewing t-shirts before I got a machine.

[CountryRoads]

I guess if you put it that way, it's not all that much sewing. I'd say the planning, measuring and cutting will take a lot longer than the actual sewing. The down stuffing will happen all at once at the end, so I'm not there yet, and I'm sure that is not going to be easy...

[Bushwhacker]

Some advice you'll find on here says your chamber height should be 0.5" to 1" taller than baffle height. When I designed my UQ I worked around an estimated temp rating based on the Jardine formula. I made my baffles 0.5" shorter than chamber height.

What I've noticed is even hung unweighed, the chambers on the underside of the quilt are tight, while the sides are loose. Thus the bottom chamber are at design loft, or possibly slightly compressed, while the side chambers are actually showing MORE loft than design. So theoretically the side chambers are insulating more than the bottom chambers.

Playing with the calculator you can see the differential between liner fabric and shell fabric is mostly based on your ratio of baffle height to chamber height parameters. If they are the same, the differential is about 0.5". I am a cold sleeper, and right now I think my quilt doesn't quite hit my temp target, although I'm still testing.

The next quilt I make I am going to keep my baffle height 0.5" lower than desired loft (chamber height), but I'm going to adjust the differential. Right now I am thinking the 2 chamber's on each long edge will only have 0.5" differential, and the remaining 5 will have a 1" differential.



Usually 20-30%. I'd work within that range to make a nice even number for fill weight that you can easily measure.

Thanks, that is very useful!

[Hayduke Deckard]

This is amazing. Thanks.