Jim's clam clamps are really nice - you won't regret it. You can actually move the assembly to your door or window opening still in the clamps and install it still in the clamps. I remove them after I've nailed-off the outside edges of the casing.
Edit - See that 'NW' has posted again. I agree, clamping is crucial to a strong joint. If you're pre-measuring everything and doing a production run of all the casings in a house at one time, you'd need a number of sets of clamps in order to be efficient.
A home owner renovating a room or two at a time would be fine with one pair of clam clamps though. Pieces like this really only need to be in the clamps for about 30 minutes.
Edit - See that 'NW' has posted again. I agree, clamping is crucial to a strong joint. If you're pre-measuring everything and doing a production run of all the casings in a house at one time, you'd need a number of sets of clamps in order to be efficient.
A home owner renovating a room or two at a time would be fine with one pair of clam clamps though. Pieces like this really only need to be in the clamps for about 30 minutes.