Doug Fattic 

Agree and I would add this fourth measurement using dropout alignment tools to make sure the dropout faces are parallel to each other. It is necessary to go through the other steps 1st because it is possible that the cups match but that the fork is still not in alignment. It is a bit tricky to get all 4 right because as Tom says when you move one it changes another. It is necessary to clear all 4 checks before the fork is really right. Some other observations:

1. I never use a bending assistance tool (except gloves) because I get a better feel for how much to move. It is really easy to over bend. The reality is that a blade won't seem to budge with moderate force and then suddenly with just a little more effort, it gives way and moves a lot.

2. Don't assume any fork or frame was aligned within a millimeter of straight when it was new. The "no hands" test is effected by the frame's alignment too. The best aligned steel frames to come into my shop for painting where Japanese frames, followed by Italian frames after frame making equipment from companies like Bike Machinery became more common (mid to late 80's?). The classic era British frames can often be way out (although a few were spot on).

3. How much a customer noticed the ride improved after an alignment varied on the person. I've aligned hundreds of frames and often asked the owners if they could tell the difference. Some said a lot of difference and some said they couldn't tell at all. I think some are just more sensitive to how their frame feels.

4. Park dropout alignment tools are not accurate enough for me and I recommend to my framebuilding class students not to buy them. The reason is that instead of using washer like spacers for different dropout widths, the cups are threaded to their handles and the slop in the threads are too much variance for me.

5. There should be a little space between the cups otherwise the dropouts might catch on the axle nuts.

noglider 

4. @Doug Fattic, thanks. I left out the dropouts. I have the Park tool, which is unusual for a non-professional mechanic, but I use them a fair bit working on my bikes and my friends' bikes. Interesting point about the misalignment possible. If I ever need to buy another set, I'll get a kind that is not subject to that problem. DIY ones might work. I remember using the Campagnolo ones, and they did feel more precise but also less versatile, i.e. fitting fewer sizes.

Doug Fattic 

I shouldn't sound too snobbish about framebuilding tools. I do expect both myself and my students to make frames to the highest standards so good tools can really help. We use the Park tools in our workshop in Ukraine where we both make frames and assemble them into bicycles. Park donates a certain amount of tools to charities and back 15 years ago I applied and was given BB taps and fork crown reamer and a few other of their goodies. Of course I was extremely grateful for their gift and try to support them as much as possible. Here is a picture of part of our framebuilding tools wall that includes their dropout alignment tools.