[EvolutionArmory]

For the purposes of this thread we will be using the Yavapai slide jig due to it being easily purchased through a few outlets.

First, set your slide in the jig and indicate the bottom of the slide so it is straight. Next, use an edge finder to set Y axis zero. Find your edge and subtract half of the diameter of your tool.

Your spindle is now centered directly over the slide edge. I cut my ports so the bottom of the port is .475 from the bottom of the slide and use a half inch cutter so now I move Y .250 and the cutter will line up with the edge of the slide perfectly. Then I move Y .475 and now I know where to stop.

Next you will edge find the front of the existing port to find out where the stop for the X axis is in the same manner you did Y. Once you center the spindle on your X move X .250 so your cutter will stop there and zero your machine.

Now that you have your stop points it's time to cut. I start from the rear and work forward. I set my cutter in the existing port and walk X in until I make contact. Once you make contact machine Y until your port stops .475 from the edge. Once you are at your .475 point machine X until you hit the X zero you set previously. I also machine a live round relief so I go about .045 past X zero and then go back.

It should look like this at this point.

 

[EvolutionArmory]

Next we machine the flair. Tilt your jig 30 degrees and make sure the fixture is VERY secure in the vise. For this step I use a 3/4 ball end mill.

To set up the ball mill I lower the tool into the port and walk it in until the tool just barely misses the bottom of the port we just cut (Y axis). Not exactly precision measuring but it works for my purposes. Now we set Z zero when the cutter makes contact with the side of the slide. We will be making several .010 passes til we make the flair about .090 deep.

 

[EvolutionArmory]

Next we flair the inside of the port. For this I use a 3/8 ball end mill. Set the jig up like pictured, touch the end mill to bottom of the port and zero Z. Move Z .100 and cut in your bevel. Use your best judgement how deep or long you want to make it.