I was asked how I cut the clean holes on the tangent of the swirl pot. While I do have access to Abe’s tube notcher, this was simple because the holes were drilled at 90 degrees. I used a bi-metal hole saw that I purchased at Home Depot (sharp tools make clean cuts). I dropped a scrap piece of tube into a vice on the mill so that when I dropped the quill it would just miss the end of the tube. This allowed me to see where the saw would plunge and to move the Y-axis until it looked like I had everything lined up perfectly (i.e. the outer edge of the cut was just inside of the ID of the tube at the middle point). I then slid the tube under the hole saw, put some oil on it and cut away… nope, I was off a little so I tweaked the Y-axis and did another test cut…. bingo, it was spot on.
In went the real piece, I aligned the x-axis so that the middle of the saw was aligned with the sharpie mark (see on first hole above) and the hole came out perfect. I moved the X-axis and drilled the second hole. The inside was cleaned up with a deburring tool similar to the one shown below and the outside was cleaned up with the tube finisher discussed in a previous post.
This could have been done almost as easily using a drill press and a drill press vice. I would orient the vice so that the fixed jaw was closest to column, clamp a piece of scrap and eyeball alignment the same way as described above. Since you can’t tweak the X-axis on a drill press, I’d cheat the fixed jaw a little closer to the column so that shims could be used to tweak the position. I keep scraps of every thickness in a box to use as shims when mocking or machining parts. If you don’t have a cache, just order a bunch of small pieces of various thicknesses from McMaster. I’d then clamp the vice to the table, do a test cut, and shim as needed. The only trick would be to not rotate the tube when drilling the second hole.