I've read your book and I'm looking to purchase the hardware kit with DVD as well as an electronics kit. I would like my machine to have a working area of at least 24" wide by 48" long. Can I just m

Considering enlarging the machine, might have its down sides do to the structural integrity of the scratch build machine. Primarily by making the width longer it will start to sag in the center, which will lead to having to redesign the gantry to be more structurally rigid to support the added length. Which then will increase the weight and height of your gantry to support the add size, which will always end up to creating a larger CNC. We usually do not recommend modifying the scratch build CNC, due to the very limited capabilities, and the structural design of the scratch build. We also do not recommend using longer than 48" ACME screw/leadscrew due to the increasing chance of warping and bending in the ACME screws/leadscrew in the given length. We do recommend modifying the CNC machines we sell to accommodate the added requests that some of our customers desire, but you will be limited to the width of the gantry with our machines.