Originally Posted by
TMToronto
I had never seen that type of end mill before, but I can see how it helps the O ring or round gasket material spread out below the surface - I imagine that helps with proper compression as well as avoiding pinching at the mating surfaces. From what I have read the geometry also helps to keep the O ring securely in place, which might be an added benefit for vacuum fixtures. I watched a few videos showing them milling their slot. Am I correct in that they require a hole to be drilled first to allow them to lower to the correct Z depth before they start milling the slot? I think I saw that in a few videos.
Originally I was going to purchase the one from Pierson - see below - but perhaps I may give the O ring cutter a try as well. Pierson sells them for 1/16" and 1/8" gaskets, and these cut a square bottom and chamfer at the same time. I purchased extra aluminum stock to practice on both for feeds and speeds but also to experiment with the correct DOC. I found some resources for O ring groove design/sizing that are informative, but geared more for industry users and applications, but still interesting to read through.