There's one problem, the line that goes from SP to 45ºVP doesn't make a 45º Angle with the vertical line that goes from the CVP to the bottom. Accuracy is very important when making grids (specially because you're going to use some of them later in C.06 as underlays), so I'd recommend - in case you don't have / are not familiar with a program that allows for more precise drawing - to do the exercises on A4 paper with a straight edge, protractor and compass.