08-31-2015, 02:36 PM
I had a similar mill/drill. I also found the head pinch to be completely inadequate. The first problem was that the pinch bolts were made from really terrible steel and literally wore out. $55 over at Fastenal for suitable replacements -- grade 8 SAE fine thread and matching nuts -- and that particular problem went away.
Then the head casting cracked. The strange thing is that the head still locked up on the column perfectly well.
I looked it over and decided that if I were serious about keeping the thing (I wasn't locked into continued ownership of a smaller machine), I would consider fabricating a replacement head out of steel as a welded construction, with a few upgrades, mostly a split-collet head fixing solution, and maybe an extra inch or two of throat depth.
Before you go shaking your head, mumbling "that Roadracer, he's crazy".... think about it: it's just a box with a couple of cylinders inside it. There are three precision holes in the box: the quill, the column, and the downfeed. Heck, the downfeed isn't even all that high precision. Then after that, there are a bunch of tapped holes.
I'd build it entirely out of mild steel plate, maybe 3/8". The quill and column holes would start as tubing, and should be rough bored .15" undersize to allow for possible weld distortion, then finished on a knee mill after welding. The two holes which matter most (quill & column) can be bored in one setup.
What would be super cool would be to design it in CAD so it can be laser or waterjet cut with interlocking tabs and slots to ensure correct alignment when assembled. I'm sure if you reached out to some US-based members that they would be happy to help you get this service -- I have a very good waterjet vendor, and I can help, but I'm in CA... shipping would be a killer. Perhaps someone on the East Coast can git'r'dun.
Then the head casting cracked. The strange thing is that the head still locked up on the column perfectly well.
I looked it over and decided that if I were serious about keeping the thing (I wasn't locked into continued ownership of a smaller machine), I would consider fabricating a replacement head out of steel as a welded construction, with a few upgrades, mostly a split-collet head fixing solution, and maybe an extra inch or two of throat depth.
Before you go shaking your head, mumbling "that Roadracer, he's crazy".... think about it: it's just a box with a couple of cylinders inside it. There are three precision holes in the box: the quill, the column, and the downfeed. Heck, the downfeed isn't even all that high precision. Then after that, there are a bunch of tapped holes.
I'd build it entirely out of mild steel plate, maybe 3/8". The quill and column holes would start as tubing, and should be rough bored .15" undersize to allow for possible weld distortion, then finished on a knee mill after welding. The two holes which matter most (quill & column) can be bored in one setup.
What would be super cool would be to design it in CAD so it can be laser or waterjet cut with interlocking tabs and slots to ensure correct alignment when assembled. I'm sure if you reached out to some US-based members that they would be happy to help you get this service -- I have a very good waterjet vendor, and I can help, but I'm in CA... shipping would be a killer. Perhaps someone on the East Coast can git'r'dun.