Fitting ferrules. The male ferrule is machined a generous 0.001 inch larger than the inside diameter of the female ferrule. The rodmaker makes them fit.
First, some measurements. I take three readings, one at the tip, one in the middle and one at the back.
As can be seen both of our ferrules have higher readings as we move away from the tip. This is very common. While my micrometer reads to 5 decimals I do not work to that level of precision. This gives me situational awareness and I will account for the dimensional variations when taking material off. I will start reducing the back end and slowly move towards the tip to even out the dimensions all along the barrel. Then I will take material off across the barrel all at once in many small steps.
I also measure the inside of the female ferrule using a small hole gauge to see how much I need to reduce the males - about 0.0015.
Interestingly if I turn the gauge 90 degrees inside the female ferrule the gauge starts rubbing tightly on the walls and I need to adjust the gauge to get the proper reading.
and nothing I can do about it. We will still get a very good fit as the difference is so small.