This is a portion of my CNC motion control board assembly documentation.

CNC Controller Motion Board Transformer Installation (Rev. D)

The transformer is Jameco 221410 and it is installed in the following steps:

Using an ordinary piece of paper (taken from the printer paper tray), the transformer is positioned into one corner. Using a pencil, the transformer feet are outlined along with the slotted holes.
Remove the transformer and touch up the traces so that they look acceptable.
Using ordinary scissors, the outpaper is trimmed to size.
Using ordinary tape, the outline is taped to the desired transformer location. I did not worry about making a mirror image of the template, since the transformer holes are symetric.
I temporarily put the two box pieces together to make the box stiff. Using a sharp metal awl, I dimpled four starter holes where I wanted the holes to be drilled. I want the drilled screws as close into the transformer as possible, since lip inteference is going to be a problem.
The hole is lined up on the drill press for holes for #10-24 hardwarae.
The first hole is drilled
The remaining three holes are drilled.
The hardware for each hole consists of 1/2" #10-24 round head screw, three #10 washers, a #10 lock washer, and a #10-24 hex nut. The picture only shows 2 washers per hole, but when I finally put the transformer in, I wound up using three #10 washers.
The paper template is no longer needed and it is removed.
For each hole, I insert the 1/2" #10 round head screw through the hole from the outside. Next, on the inside, I put two #10 washers, followed by the transformer leg, another #10 washer, a #10 lock washer and top it off with a #10-24 hex nut. When all four screws are mounted there is a little play in the transformer left to move it around a little. After it is positioned "just right", all four screws are tightned down hard.
Afterwards the transformer is not going anywhere.
Next I put the other box piece on and notice that the washers interfere with the box lips. I knew that was coming.
Using a nibbling tool, I start removing metal in all the places where the washers are hitting the box lip.
When I am done, there are three notches in the box lip -- one in the corner, one in the middle of the top edge, and one in the bottom side.
When the box is put together, everything fits just fine.

	Using an ordinary piece of paper (taken from the printer paper tray), the transformer is positioned into one corner. Using a pencil, the transformer feet are outlined along with the slotted holes.
	Remove the transformer and touch up the traces so that they look acceptable.
	Using ordinary scissors, the outpaper is trimmed to size.
	Using ordinary tape, the outline is taped to the desired transformer location. I did not worry about making a mirror image of the template, since the transformer holes are symetric.
	I temporarily put the two box pieces together to make the box stiff. Using a sharp metal awl, I dimpled four starter holes where I wanted the holes to be drilled. I want the drilled screws as close into the transformer as possible, since lip inteference is going to be a problem.
	The hole is lined up on the drill press for holes for #10-24 hardwarae.
	The first hole is drilled
	The remaining three holes are drilled.
	The hardware for each hole consists of 1/2" #10-24 round head screw, three #10 washers, a #10 lock washer, and a #10-24 hex nut. The picture only shows 2 washers per hole, but when I finally put the transformer in, I wound up using three #10 washers.
	The paper template is no longer needed and it is removed.
	For each hole, I insert the 1/2" #10 round head screw through the hole from the outside. Next, on the inside, I put two #10 washers, followed by the transformer leg, another #10 washer, a #10 lock washer and top it off with a #10-24 hex nut. When all four screws are mounted there is a little play in the transformer left to move it around a little. After it is positioned "just right", all four screws are tightned down hard.
	Afterwards the transformer is not going anywhere.
	Next I put the other box piece on and notice that the washers interfere with the box lips. I knew that was coming.
	Using a nibbling tool, I start removing metal in all the places where the washers are hitting the box lip.
	When I am done, there are three notches in the box lip -- one in the corner, one in the middle of the top edge, and one in the bottom side.
	When the box is put together, everything fits just fine.