I’m curious if anybody knows how to calculate the differential difference between an inner and outer shell using cat splats calculator? It definitely shows that the outer shell needs to be wider than the inner shell but it does not calculate spacing.
Maybe I’m looking at this wrong, but if I use nine baffles according to the calculator that puts the spacing on the inner shell at about 5 7/8 inches in between baffles on the inner shell. The spacing looks almost too big as everything I can read. Seems to indicate you want your spacing somewhere between four and 5 inches ideally. It also looks like I want to achieve around an inch difference in between the height of the baffle and the top of the outer shell to achieve the correct calculated lofting of about 3-3.25”.
I just looked at it quickly but it seems to be correct? You need a wider outer shell to accommodate the longer curvature and give the down room to loft.
I'm not sure I follow what you're saying and I'm not an expert but I have used the calculator for the quilts I've made so far.
If you look under "Output" column in the middle there are values for IWB and OWB- those are your spacing values. In the image you've shared, those values show at 4.9 and 5.5 inches respectively. So if I was making that quilt, I would sew the baffle material each 4.9 inches on the inner material, and each 5.5 inches on the outer material- don't forget to account for the side/baffle height and seam allowance on the outside edges. So measuring from the outside long edge on the outer material, the first actual baffle material would be sewn in at 2.75+5.5+your seam allowance onto the outer material.
Also I'm not sure where you're getting the 5 7/8 value from. When I input your numbers into my copy of the spreadsheet I got different values in the "Fabric Calculator" area. Your image shows Each Baffle size 69/5.89inches, my copy of the sheet shows 69/3.8inches
The difference between the baffle spacing numbers is what allows for the difference between your baffle height and the full chamber height.
It's a lot of information to take in all at once when trying to get started.
One thing I saw mentioned somewhere- that I wish I'd done before going all in on my first underquilt, was to make a miniature version to practice. I think if I'd done that it would have let me understand with less pressure how the info in the calculator and tutorials I'd explored actually translated to the finished product.
If I was starting again, I think I'd go get some lightweight muslin and make a mockup, maybe even stuff it with something like milkweed fluff, to go through the process on something that I won't be heartbroken if I really mess something up. And if it came out well I could give to a friend with a cat or something. haha.
You can do it. Take your time, go slow- those slippery fabrics can be a bugger!
Oh, don’t get me wrong. This is not my first rodeo. I originally bought all the supplies I believe in 2020 and then chickened out. I have since made one synthetic -10° UQ, several tarps, bags, stuff sacks, one failed pack (poor design).
Ready to tackle my first projected 0° quilt in Black and Blue I am calling El Moretón
Yeah, I've seen you post some of what you've made, that's why I added that "You can do it" and realize it probably wasn't clear I had your other shares in mind. And the rest of it after was as much a reminder for myself and to others who might be reading. :)
I'm looking forward to seeing the end results if you decide to share.
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u/GilligansWorld 3d ago