[Hammer1]

Why don't you try what you have without magnetizing. I doubt you'll have any problems. Make sure to unplug the saw first. When you place the dado set, push the first outside cutter tight to the arbor flange and hold it with one hand, then progressively add chippers and shims as needed, keeping each one tight to the other. The shims don't have to be distributed between all the chippers unless the sum is larger than the overlap of the carbide teeth. You may be able to make small adjustments by just removing the outside cutter and changing the shim between that and the first chipper. As you place each cutter, position them so they balance evenly around the arbor and no teeth hit each other or the plates. Lay out your dado set in order ahead of time so you are ready to go and not fumbling for things. You can feel and see if things are fitting nice and flat to each other. Since the arbor threads spiral, the shims don't just drop into the groove easily, you might catch one once in a while but it shouldn't be frequently if you take a little care placing everything. Don't crank on the arbor nut, just lightly firm with any blade.

 

[Hammer1]

Many pros do what is often called a "story pole" for planing projects. It's nothing but a stick of wood and you use it to layout each dimension, height, width, depth. You can use either the back and front of the stick or use more than one stick for each dimension. Using your shelf measurements, you would square two lines across the stick 13.25" apart. Next you measure the thickness of the shelf material. If you want three shelves evenly spaced, you take the sum of the thickness of three pieces, exactly. If they are 23/32" that's what you use, don't round up to 3/4". The unit will have four spaces between three shelves. From each mark at 13.25" either measure or use a scrap of the shelf material held on each line, then mark the stick accordingly. This marks the top and bottoms of the unit. Take a measurement between these two new marks. Subtract the sum of the number of shelves from that measurement. Divide the result by four for the four spaces. Measure down that number from the mark you made for the thickness of the top. Then use a scrap of the shelf material to mark the location of that shelf, repeat by measuring the same distance from the bottom mark of that first shelf, etc. You have to use a sharp pencil since any slight error will multiply by the number of spaces. Once you have the story pole marked correctly, you can use that to mark the work pieces.

If you have other issues with width or depth, you use a separate stick or surface to do the same. If you were dadoing the shelves into the sides, after marking the thickness of the sides, you then mark the depth of the dadoes or any other joinery you may be using. The story pole will give you all the measurements you need, your cutting list. Learning to use story poles means you will not need any plans for anything you want to build. It's just a matter of knowing the overall dimensions and filling in all the details. Since this is done in full actual size, the story pole can be used to directly check or mark out your work.