Hi Mike
I suspect it's because you don't have the jumpers installed that tell your drivers what micro stepping mode you are using. If you have A4988 drivers and have set your steps per mm in Marlin to use 1/16 micro steps you need all three jumpers populated on the Sainsmart board. I believe they ship without them.
Or you have your homing federate set too high. Default in most Marlin forks is 200*60 changing hat to 100*60 for x,y and z may help
Andy
I suspect it's because you don't have the jumpers installed that tell your drivers what micro stepping mode you are using. If you have A4988 drivers and have set your steps per mm in Marlin to use 1/16 micro steps you need all three jumpers populated on the Sainsmart board. I believe they ship without them.
Or you have your homing federate set too high. Default in most Marlin forks is 200*60 changing hat to 100*60 for x,y and z may help
Andy