Friday, February 18, 2011

Finishing the Generator Cover

I managed to stay late and squeeze in some more machining to finish up the generator cover.  After ending the last post with the first setup finished I then machined a simple fixture plate to locate on the interior features of the part.  it used the stator mounting bolts and a couple of mounting holes with dowel pins to keep the part accurately aligned with the previous operation.

Second operation fixture plate:


Loaded in the mill with a part installed:


After rough machining:

With it's brothers:



I gave one a light glass bead blasting to reduce the reflectivity of all the shiny machined surfaces.  The result looked great:


The round cap part has M50x1.25 metric threads that were made on a lathe with a normal threading cycle, like most externally threaded parts.  The cover part then needed an internal M50x1.25 thread which would need a special M50x1.25 tap, which would be very expensive, or I could make the thread using a thread mill, which is the option we used.  Thread milling uses a 60 degree V-shaped cutter that is moved in a helical path that corresponds to the thread profile.  If everything is done properly you end up with a very clean and accurate thread without the need for a tap.

Here's a video of the thread milling operation.  It is done 3-4 times with an incrementing depth of cut and a small finish path.
video

These parts are now finished and the next step is to make the gerotor pump and bearing shaft cover.  Look for a post sometime next week for more.

Until next time.

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