I started out quilting, years ago, on a Bernina Artista with my older elna as backup. That's when I discovered 1/4" on one isn't necessarily a 1/4" on all. Unfortunately . . .even using two different brands of quilting rulers can throw off a project as well. I think the problem could be the measurement system. In the US, we use imperial measurements while the rest of the world uses metrics. So when making feet, the imperial measurements can be off.