Dave,
It seems we basically agree; "mag bases are the way forward".
In ten years heavy boiler work I have never used a drilling pillar; I have watched others wasting their time wrestling with them and getting fair to poor results; but get the job done eventually. Air drills not really that good for drilling; in the same way that ratchet drills before them weren't either but I can manage the big air drills free hand if I need to (but more for bridge reaming or c/sinking than drilling) and the medium ones are useless as they (or at least the ones we have) spin too fast for even a 1/2inch drill which an decent electric pistol drill will handle anyway.
I also do the ratchet strap fixing for a mag base thing and have made a ratchet strap fixed mag base base specifically for barrels using about 15" of large channel about 8"x3" cutting ratchet strap shaped slots in the flanges of the channel towards each end so the channel device can be strapped to the barrel "legs" down and the mag base sat on the web. I have also made one with odd length legs for when working around a doubling plate so longer leg sits on the barrel and the other sits on the doubling plate but the part where the drill sits is still generally tangential to the barrel.
|