I also have the Dremmel brand, however, they now make them to actually "fit" your hand--kind of curved shaped. I do not recommend this type, as it is very difficult to use at the correct angle.
When using the Dremmel, you should also know that you can not sit there and "grind" on your dogs nail for a long period of time. The Dremmel causes friction and heat on the dogs nail, which in turn, helps retract the quick. However, you can cause pain if held on the nail too long. After you do it for a good amount of time, you will become a Dremmel master
And yes, it will take some time for your dog to get used to it. The biggest thing is the vibration. Take it slow, have patience, and reward.