Check Your Seam Width Between Machines
I took my Featherweight to my sewing social group and made up 30 4-at-a-time flying geese. They all came out exactly 2 1/2 x 4 1/2. Perfect.
I came home and did the other 70 on my Janome...and they are all just a bit too small. I didn't bother to check them because the others all came out right and it didn't occur to me that it might be that the machines 1/4" foot might measure differently...
So, don't learn the hard way like me. Check your pieces for sizing every time when you start a new block.
Watson