Tuesday, February 17, 2009

Turning on a...

Ok, this might be exciting if it was the first thing that I ever turned on a lathe, but it isn’t. I don’t own a lathe…

_It is_ the first thing that I’ve ever turned on the Bridgeport mill. Basically I set it up with an R-8 arbor mounted 4” lathe chuck, and then clamped a lathe carbide tool in the vice and used the quill downfeed to feed it past the lathe bit, the setup looks like this:

FWIW, that finish was the result of a .027” depth of cut. I intended to do another clean up cut, but when I measured the piece that it was supposed to press into I made the mistake of measuring a scrap of the pipe that was cut off next to a weld so it measured smaller than a new piece of the pipe (for those of you that don't know, welding ‘shrinks’ the piece), so I ended up with the fit that I wanted without the clean up cut that I thought I was going to make. Otherwise, it was done with the Bridgeport head pulleyed all the way up (2850rpm), but with the VFD set at 10hz, making it roughly 475rpm (the heavy cut was interesting because you noticed the torque management on the VFD kick in as it hit the heavy part of the cut to maintain the set speed).

What’s really neat about about this setup is that since the Bridgeport table has a DRO on it, I can quickly cut identical diameter parts just by zeroing the X axis and feeding the table over (effectively, feeding the cutter in) till the DRO shows .0000”. I can also cut any angle relative to it that I want by rocking the Bridgeport head over to the angle I want to cut and using the table Z axis feed to make the cut.

If anyone is wondering what it is, I couldn’t find black iron threaded caps big enough to cap the ends of some pipes, and the store couldn’t thread that pipe size either, so instead I found caps that almost fit inside the pipe and am going to press them into the end of the pipe with the press and then weld them in to seal them up. That will look a lot neater than threading on caps anyway. When they’re done they’ll get a couple of fittings welded to them and a valve added to the bottom and be used as moisture separators/drains for my air lines.