I was going to post a question about making a large washer -- 2.625 OD, 1.06 ID, about .375 thick -- until I realized I could buy almost exactly what I needed from Fastenal .. problem solved. The tolerances are pretty loose in this whole problem -- 2.5" or 2.75" OD would be OK, as would a 1.125" ID, or .400 thickness, etc.
But since I was going to ask about this sort of thing anyhow, I might as well proceed.
My plan was to make this from some flat stock: Mark a center and a 2.625" circle, drill a 1" hole using the milling machine, cut that out roughly with the bandsaw, put the piece on a mandrel and chuck it in the lathe, and then make it a bit more properly round (which probably means doing an interrupted cut, since my bandsaw work will probably end up making something like a 16-sided polygon rather than a circle), press out the mandrel, re-chuck the piece in the 3-jaw chuck, and bore it out a tiny bit larger (or use a 1 1/16" drill, which is close enough).
Alternatively, I could have gone back to the milling machine to drill that last hole, and that's where my question arises:
When you've got a relatively small, relatively thin, piece of material that you want to work on using the milling machine (imaging that I want to make the center circle into an oval, say), how do you hold onto it? Or is this just a bad idea, and I'm supposed to do something entirely different? This problem, in various forms -- small pieces that I can't seem to hold well -- keeps arising, and I figure someone must have solved it. My only thought so far was to make a "sandwich" with my piece between two slabs of aluminum, with through-bolts to clamp the aluminum pieces together. Of course, that means I can't see the workpiece any more...but at least it'd be held fairly securely.
Any suggestions for an amateur like me? (My general approach is to give up, because I'm really scared by what can happen to pieces that get loose...)
But since I was going to ask about this sort of thing anyhow, I might as well proceed.
My plan was to make this from some flat stock: Mark a center and a 2.625" circle, drill a 1" hole using the milling machine, cut that out roughly with the bandsaw, put the piece on a mandrel and chuck it in the lathe, and then make it a bit more properly round (which probably means doing an interrupted cut, since my bandsaw work will probably end up making something like a 16-sided polygon rather than a circle), press out the mandrel, re-chuck the piece in the 3-jaw chuck, and bore it out a tiny bit larger (or use a 1 1/16" drill, which is close enough).
Alternatively, I could have gone back to the milling machine to drill that last hole, and that's where my question arises:
When you've got a relatively small, relatively thin, piece of material that you want to work on using the milling machine (imaging that I want to make the center circle into an oval, say), how do you hold onto it? Or is this just a bad idea, and I'm supposed to do something entirely different? This problem, in various forms -- small pieces that I can't seem to hold well -- keeps arising, and I figure someone must have solved it. My only thought so far was to make a "sandwich" with my piece between two slabs of aluminum, with through-bolts to clamp the aluminum pieces together. Of course, that means I can't see the workpiece any more...but at least it'd be held fairly securely.
Any suggestions for an amateur like me? (My general approach is to give up, because I'm really scared by what can happen to pieces that get loose...)