Proper way to build a footbox with a climashield quilt ??

hmmm. are you talking about having a sewn in footbox? i'm fairly certain the footbox on my quilt is a separate circular disc of insulation that is sewn to the rectangle of my quilt, then the bottom of the quilt is sewn up to around my knees.

if you sewed the circular disc onto the quilt (kind of like just putting on the cap of a pringles can) that the stitch line (which would be where you'd have a cold spot) would be hidden b/t both the sides and the cap of the insulation. i don't know if that makes any sense, but i have a picture of it in my mind…

I will probably (hopefully) figure it out when I get there fabrication wise.

IE my last method in basic terms was to lay everything out, inside out, 2 pieces of fabric on the bottom and the insulation on top then sew the perimeter then flip it inside and close the opening.

With a foot box I will need to attach the outer circle to the outer shell, then the inner circle to the inner shell first, I think, then sew the perimeter but I think I should leave the inner and outer footbox sections, and short closed section up the quilt unattached.

I am just having issues trying to figure out the exact procedure to sew everything together.

A drawstring footbox quilt is a lot easier to build.

When I made my climashield quilt (5oz), I made it tapered to save weight and I originally had a drawstring foot. Then tried a zipped and velcroed foot…
Then, I finally decided this was too tight for my size 13 feet, and retrofitted a circular panel.

Having tested the quilt, I also found that 40*F was a low as I'd be comfortable to use it, so I figured that by sewing the foot panel on afterwards having an almost 'stitched through' seam would not be too bad heat-loss wise. By stitching the already sewn edges together , it means that there is a sort of thicker multiple layer of seam allowance which acts as a 'baffle' at the join.

(Obviously, the Finished circumference of circle is same/close to as the length of end edge of main quilt)

To attach it, I pinned it, and started sewing at the centre of the quilt and worked both directions in turn around to the back, then sewed the long edge up some way to create a permanent foot box.

As I made the footbox fairly big, it's also worked out well as a good synthetic overquilt for a lighter down bag.

What temps now with a foot box.

My plan all along has been a shell I can open up and insert whatever insulation inside.

I think what I will do is leave the inner foot and outer foot section including the section that is sewn vert up the bag for 18" or so separate. I am going to sew on one layer of 2.5 xp to the round foot section and a short piece around the feet maybe 12" up.

Then when I open it up I will basically have two separate foot ends. One will be an inner and one an outer.

I will make liners that are mummy shaped so when the shell is inside out the foot area of the liner will slip over the M90 inner section. Sort of like a bag inside a bag. Will probably need a couple of pieces of velcro here and there.

The liners will be either fully covered with silk or just one one side to help stabilize it.

It will basically be sort of like a Silk 5MM covered quilt with a M90 shell Cover.

Think I will build the 5mm Silk quilt first for practice.