Originally Posted by
ghostrider
I won't even set mine down below 2.0 for paper piecing because it messes up the block size too much. For regular piecing I use 2.5 (a bit over 10 stitches per inch).
Here's how to convert back and forth easily between the settings and stitches per inch.
The basics:
The metric machine settings are the length of the stitches in millimeters. Example, a 2.5 machine setting means the stitches are each 2.5 mm long.
There are 25.4 millimeters per inch.
To get how many stitches per inch that setting equals...
25.4 ÷ 2.5 = 10.16 stitches per inch.
Dividing 25.4 by the machine setting gives you the stitches per inch.
If you want to get the setting to sew 8 stitches per inch, you go the other way...
25.4 ÷ 8 = 3.06 (round to 3.0) machine setting.
Dividing 25.4 by the stitches per inch you want gives you the machine setting you need.
Easy, yes?
Yes, easy! But, being empirically oriented, I had to go and measure. And my machine is not conforming in its actual stitch lengths to the mm/in conversion. 2.2 on my machine is 14 stitches to the inch, whereas the conversion formula result for 14 stitches to the inch is 1.8 (25.4 / 14). I should double-check the settings from top to bottom using a millimeter rule, which should be easier to interpolate.
Why my machine is so out of whack, I don't know, but as long as I measure each setting I should be able to work properly.
Thanks for the conversion formulas!