I've started machine stitching my blocks and I'm pretty pleased with them so far. I love the colours and the petals are going together quite neatly although I'll have to try to make the outside ones fit a little more carefully I think.
For the first one I used YLI fine silk thread on top and a YLI soft touch cotton thread in the bobbin. I used two shades of the silk as i tried to match the petal colours as closely as I could. This wasn't too bad but I thought the stitching showed a little around the edges of the petals so I tried invisible thread on the next one. I used YLI 'Smoke' coloured invisible thread on top and Soft Touch (white) in the bobbin. I don't think the stitching shows as much with this combination but putting the two side by side at arms length it is difficult to tell them apart! The photo shows the one stitched with invisible thread on the left.
I have used stitch number 3 on my Bernina 440 - this makes 2 straight stitches then one zig zag. I adjusted the width of the stitch right down to 0.5 so it just catches the edge ot the petal as I sew very close to the edge on the background fabric. I have to go quite slowly and concentrate but perhaps I'll get quicker by the time I make the 49th block! I was thinking I might try making a video to show how I do the stitching - would you like to see it demonstrated?