most of the Samsung front loader I deal with do have a serious shake near the start of the spin cycle. This is really tends to be amplified on units that are not on a good level or on 2nd story or weak floors. IF the shake does not go away relatively quickly then you do have a problem. A couple of other things to check: have all the shipping bolts been removed ( I know sounds stupid but I had one that the homeowner did not remove the shipping device on). Also make sure that all the feet are firmly on the floor, as the unit starts to spin and shake feel around the feet sometimes a perfectly level unit will have one foot that has loosened and although it is touching the floor it is not actually supporting any weight.