CS Underquilt Confusion

[Codger]

I am preparing to make an Apex 3.6 UQ and have been scouring the forum and web for plans. There is much talk about differential cuts in order to enable complete lofting. This concept makes sense. Where it becomes confusing is where people speak of using a differential cut WITHOUT darting. To my logic, it would be impossible to sew together the perimeters of two different size pieces of fabric without in some way reducing the larger piece to the same diameter of the smaller (such as by darting). Is this correct thinking or am I having some sort of cranial/rectal inversion? As for not bothering with the differential cut, has the performance of these UQ's proven to be acceptable? With me, it seems, sometimes too much information is a bad thing. Please someone help me out here?

[Codger]

Maybe a simpler question would be - Has anyone noticed any significant difference in performance between a differential cut and non-differential cut underquilt?

[Ofemur]

From all that I have read, that with Climashield Apex you do not need any special measures like darts, pleats, etc. Just sandwich the layers together and sew the layers together around the perimeter. No need for quilting, baffles, or anything else. CS is made such that it stays in place. Unlike down which needs baffles or other synthetics which require pleats and/darts.

[james_e84]

'm no expert but I do recommend a differential cut, without darts. I wouldn't go to the trouble of sewing in darts for the 1 in loft of the 3.6 apex. I made my first two uq's this week, the first was two layers of 3.6, for it I added 4 inches for the outer shell. The second Uq was one layer of 3.6, I made the outer shell 2 inches larger(length and width). To take up the extra material I simply overlapped the extra length in two places a little off center.(I had 4 extra inches on the 7.2 apex, so two 1 inch folds/gathers took up the slack). For the 3.6 apex I two 1/2 inch folds to take up the extra 2 inches.

Hopefully I didn't just add to the confusion.

Here is a picture of one of the 1 inch folds that takes up 2 inches of material.
image.jpg

[Codger]

Ofemur,
i agree. I understand that CS doesn't really require baffles due to its construction. However, it does require loft to function correctly. As such, it makes sense in theory to use a differential cut to provide room. But life has also taught me that there are sometimes vast differences between theory and practice. So, I guess I'm asking if someone has disproven this theory?

[Codger]

James,
Thanks for that. I saw your post after I had posted the question. You didn't add to the confusion at all. Have you ever made a quilt without the differential?

That's a nice looking quilt btw. Profs for just pulling the trigger and doing it.

[TFC Rick]

I made a CS top quilt with no differential at all. The ripstop is not tight at all, and actually I'd prefer if it were a little more snug against the Apex. I think you'll be fine.

[latriper]

Have made 3 underquilts and a top quilt, all with 5.0 Climashield. I do not use the differential cut and they all preform great. Also, I do not think AHE uses a diff cut on their quilts and they are the authority of Climashield quilts..IMHO.

[james_e84]

I say add the differential, if I pull the quilt against my body from the inner layer it does not/can not compress the insulation, I'm glad I did mine that way, nice and fluffy...

[Jeff Myers]

It is very simple. If you really want the warmth from the $$$ you put into a UQ build you need to allow for loft. It will still work "fine" as long as you hang it perfectly or do not get to close to the true rating of the insulation. But why cut corners just because others do when you can maximize the efficiency of your build?
So look at the specs....
For example your 5.0 Apex is rated at 1.4 inches loft. So now look at your dimensions say for instance to are making a 46x68 UQ. Now back to grade school math class. Length (68)times width (46)times height (1.4) and you have 4,380 cubic inches of space needed for your insulation.

In this case you need 2.8 inches added to the length and width of the outer shell to let your Apex loft (and I will tell you from experience it loft out past 1.5 )

You wanna just stitch it tightly shut with two same size pieces? Or you wanna actually have the warmest UQ possible for the insulation you bought?

The radius of the outer shell needs to be larger because it is a minimum a 1.4 inch longer radius , so the larger outer shell needs the extra material towards the center of this circle. This is why pleats where the shells meet are the best way to add dual differential technology to you quilts

Boxing is okay too, but it uses all the excess material to make the boxes out at the corner where you really do not need loft.


SIDE NOTE: This applies to UQ as the OP asked about , so all you guys posting up how your did not use differential cuts on the top quilts...well that really does not apply here guys.