Summer Quilt Project – To sew trhough or baffle?

You would be safe to sew-thru at 1.75".
The more loft you have the closer each chamber will be pushed together making the cold spot not much of a deal.

Your biggest worry will be the shrinkage involved from that fabric being pushed together.
You can expect to loose 6-8" (maybe even 10 with the 1.75' of thickness), of length and if you don't account for it and pull the fabric taunt, you will just compress the down, spread it out and get cold spots.

If you don't want to worry about the shrinkage, you can use vertical baffles and add about 4" on the top and 3" on the bottom.

Baffle direction won't determine any difference in warmth because each chamber is more taunt than with a baffle so you won't have to worry about the down shifting to the sides.

Part of my hesitation with sewing in netting to create 4 sided chambers – in addition to the time in measuring, cutting, and pinning/taping – is how to make a seam along the edges of the quilt.

How would I properly make a seam joining the two shell pieces with the end of the netting baffles? In other words, does the netting have to be sewn into the seam to close the end of the chamber?

Here you go.

http://www.backpackinglight.com/cgi-bin/backpackinglight/sewing_primer_straight_and_top_stitch.html#.Uo_5jCjWf6s

I asked a similar question to this a while back when I was contemplating sewing my own down bag. Basically what I was told was that you have two options.

1) you can run your baffle fabric all the way to the outer seam and sew it into the seam, sort of squishing the end of your baffles. The gives you fully separate baffles and keeps the down where you put it.

2) you can stop your baffle short of the outside seam and then just sew your shell fabrics up together. This way you end up with a channel connecting the ends of all of the baffles. Some people like this because it allows them to move the down around after its all sewn up.

The tl;dr version, if you want your down locked down you need to seal up both ends of your baffles. If you're ok with down movement, you can leave them open.

On a summer quilt, it probably wont make much difference between the two methods.

I started making an oversized sewn through quilt a while ago. Good thing I started making it oversized because I cut off the two sewn through baffles I made and have decided to go full baffles.

I found it really difficult to work in the middle of two large pieces of fabric. I tend not to pin, tape, or affix my fabric together. This normally works just fine for me. But when sewing two large pieces of very slick fabric together I couldn't keep them aligned, they bunched under the seam, and one piece tended to run through the presser foot faster than the other.

Sewn through may be seemingly more work, but for me I think the extra work will be worth it. Not only will I end up with a more professional well made product, but I won't stress as much while I'm making it.

Anthony

P.S.
If going full baffles saves you from pinning your fabric it may save you time, work, stress, and putting holes in your fabric