70" x 56"
I lost count after winding the eighth bobbin and changing the needle 3 times but I went through a s--t load of thread and had to scrabble around to find new needles.
Things I have learnt quilting this spiral:
(1) Quilting around and around in circles is fun for the first hour and then.....nuh...
(2) I can rest my forehead on the sewing machine and weep quietly periodically and feel a lot better for it.
(3) After stopping every so often to wind a new bobbin over the first few days it suddenly dawned on me that it was advisable to wind several bobbins at once! derrr!
(4) No matter that the stitching line width is the exact width of my walking foot...I still can't stay on a line to save myself.
(5) My Juki and its high harp space is "the bomb" and laughs at large spirals.
(6) Stop every couple of rounds and check your backing for creases and folds that you will have otherwise sewn into at least 18 rounds of stitching.
(7) Don't start to unpick 18 sections of stitching while you're still angry about having to unpick 18 sections of stitching.
8. A quilt with that much stitching in it is very heavy and hard to manouever around in a circle and going faster will not improve things at all.
(9) My pedal foot goes numb after an hour or so, and a scotch doesn't help.
(10) Spirals and curves start to look flat and straight after an hour or so.....resist the urge to freehand correct...it will not end well.
(11) It's best to make sure you have ample reels of the same colour thread before the shop closes on a Sunday afternoon.