When trying to get the correct fit of my arrow nock to my string, I have usually resorted to using sandpaper or a real small file.  I've also tried the hot water trick.
I recently came up with a new trick. I found an arrow with a good fitting nock and then started going through my drill bit index until I found a bit that slid snuggly into the nock.  I chucked the bit into my drill press, started it up and then took my arrows with new nocks and slowly pushed the nock into the cutting part of the rotating bit.
Worked like a charm.

That really does make a lot of sense for those of us who have a drill press...thanks

DDave

I imagine it would work with a hand drill as well, just secure either the arrow or the drill and basically do the same thing?

IMO that's playing Russian roulette.  You are weakening the nock when you do that, and likely you won't get the groove centered.

To get a proper nock fit, use the right size serving.  It's that simple.  Might cost a few bucks up front, but in the long run it's way cheaper than a damaged bow or damaged archer.

You're probably right Chad, but I'm not talking about nocks that are way off to begin with,  they are usually pretty close and I'm just fine tuning. If I was removing a lot of material then I would get a nock with a wider throat or do as you say, get my string served differently.

I prefer to serve my strings to fit my nocks,there are so many different serving diameters and string material diameters.I like to have my serving end up around .108 to .110,I measure with my calipers.My nocks are Easton 3D Super nocks for most carbons and standard uni-bushing and large groove G-nocks,they both have a .098 throat and gives me a light snap.

You don't need a drill press . I have done the same thing with a vice grip and use the drill by just pushing and pulling . One or two times and you have it .

Never modify the Nocks...apply the correct diameter serving. If the Nock fails on launch real bad things will happen.

Nocks can be carefully filed to fit without creating safety concerns, provided it's done carefully.  A small (thin) mill file works fine and allows more control than would a fast-spinning power drill bit.  Slower is definately better for this.  After 30 years of doing it I've had no issues yet with this method.  OTOH, using hot/boiling water to 'spread' nocks apart can definately stress/weaken them.

I use two Emory boards and lightly drag them thru the Nock....

Most of my bows are in the mid-40's and I can pretty much shoot all of my arrows from each of them.I have all the same nocks on my arrows - standard GTs - and I have my strings built to fit the standard GT nocks. An old man really likes simplicity.