I think it's really important to experiment with the heights you use. I hunch if I use a machine that's shorter (like a featherweight) even if my elbows are at 90 degrees. I cut way higher than most people say you should, but I can go at least a half day without pain, even with 2 bulged disks in my back. Use 2x4s to raise tables and such to see if you want it higher and give it a good test, not 5 mins and decide no. To "lower" for testing, I leave my table at its default height and raise my chair and put my pedal on a raised block or something. I wrote about some of the ergonomics here: http://www.archaicarcane.com/high-en...r-sewing-room/ - There's cutting table stuff below the LA stuff. One thing I said in the post and something I will always stand by is "Your tools must conform to your needs, not the other way around."

Silly me, I said 45', 90' is correct.

I only stand to cut or iron. I would like to teach myself to stand also. Don't want to move a machine to do it.
I have a fold up table from Joanns and it is the right height for me. I'm 5'-7".

I just raised my sewing desk to the height of my cutting table. That's up 7" from what it was. Because the machine is recessed, it's probably just below standing height. I use the same chair now for cutting, sewing and quilting - a saddle stool. I've only had about 30 minutes of sewing at the desk, but so far I love it. I raised it by using some of the stacking wood stab jack thingies we use for our trailer. Will try to post a pic later if anyone's confused by my extremely excellent description ;) or wants to see them anyway.