What are the best sewing machine needles? What size is the best for piecing quilts? How often do you change them?

For piecing, I like Sharps 80-12 and change needle after each major project. Fav brand is Klasse`.

Schmetz, no question. I piece with 70/10 sharps and quilt with 75/11, 80/12 or 90/14, depending on the thread. I change them often, at least every project and sometimes halfway through if I'm using poly batting or batiks which wear the needle more quickly. An old needle can strain the motor on your machine and a new needle is a darn sight cheaper than a new machine. :-D

"Superior threads" they have excellent info and videos on threads and needles. it is under the "education" tab.

http://www.superiorthreads.com/education/

great video on needles!
http://www.superiorthreads.com/video...titch-needles/

For my first quilt I used Superior's 'titanium coated topstitch 80/12' needles for quilting my sandwich. Pricy yes, but along with using quality thread had not one itty-bitty problem with the process. I like that. Definitely like/love these needles, although I will be looking into the Klasse`.
For piecing the batiks, I used either a Singer or Dritz ball point 75/11; have a lot on hand (from years of garment construction) and get no snagging of fabric threads with the ball points.
Goes without saying, new project/new needle.

you should change your needle between each project or after 8 hours of sewing time -- sometimes more often- some fabrics dull a needle faster than others- if you are sewing along- and find your stitch quality is no longer good (skipping stitches-uneven stitches-and even thread breakage) the reason is usually a dull needle

same here!

I learn so much here!!!

Like Watterstide I use Superior Threads titanium needles 80/12, unless I'm working on lawn cotton or silk - then I use their 70/10.
Based on Bob Purcell's advice I now use the 70/10 when I'm using his Bottom Line thread in the needle.

I've already said this on a different thread - October 2009 is the last time I put a new 80/12 in, and my Bernina is sewing like it did when the needle first went in.

http://www.superiorthreads.com

I use 10's, 11's or 12's for piecing, depending upon the size of the thread.

I use Organ Brand mostly - I can buy them on eBay for as little as $12 per 100 and they're really nice needles.

I recently bought Orange Brand to try them out - again, about $12 per 100 and they supposedly use German engineering and quality control in the manufacture, so I think they're going to be fine.

I've never had any problem at all with the Organ brand, but I do change the needle quite frequently no matter which brand I'm using or what machine I'm sewing with. When embroidering or FMQ, I only put about four hours on each needle and I change it before any problems start showing up. For regular sewing and piecing, I usually change the needle after six or eight hours.

I also like Klasse' and Schmetz brands - they cost a lot more, but they make a lot of specialty styles.