An end plate or end ring for a raised pillar reel has many details, so many things can go wrong. One preventable error is failing to center a counter bore on a drilled hole.
When I started the raised pillar effort, I was making counterbores with an ordinary end mill. This quickly proved to be a bad idea. The solution is to use a real counterbore which has a pilot that ensures centering.
There are two problems in obtaining these tools. First, they can be expensive. Second, you cannot find the combination of pilot and cutting diameters that you want.
My solution to the first problem is to buy the tools on Ebay. I now have one counterbore from Israel and one from Croatia, but they cut just fine.
My solution to the second problem is to buy “replaceable pilot” counterbores and then make my own pilots from mild steel.
Update 13 Dec 2014: At the time of the original post, I made my own pilots for 7/32 and 3/16 counterbores. While I was making aluminum frame reels, the pillar screws were 4-40 and the 7/32 counterbore worked OK. Now that I started making frames of bronze, I have switched to 3-48 screws, and the 3/16 counterbore for those is not satisfactory. The problem with it is that the diameter of the pilot (which I made) is a little less than the minor diameter swept by the cutting edges. It does not make a flat bottom hole. So I am back to using a 3/16 end mill to form the counterbore. Working carefully on angular positions, I am getting satisfactory results.