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Re: Machining G10, machinist opinion
Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
When your machinist does the rotor, have him punch a center point,
and draw an outer diameter from this point using a trammel/circle
marker. This center point is the reference for everything. You can
then rough cut the disc using a bandsaw and drill the center hole of
the correct size for mounting on to the motor shaft with a tight
fit. This tight fit will properly locate the rotor with respect to
the motor shaft. The mounting holes to mount the rotor to the arbor
only hold the rotor in place and should not be used to center the rotor.
The rotor can then be mounted on a rotary table using this center
hole as a reference (may need to get an appropriately sized
bushing). The rotary table is mounted to the mill's XY table and the
table positioned for the correct rotor radius. Have him use a TIN
coated cobalt four flute end mill to machine the G10. The rotary
table can then be slowly turned as the mill trues up the outer
diameter of the rotor. Have him use a conventional cut and NOT a
climbing cut. The same setup can be used to drill the holes for the
tungsten. The rotary table will insure that each hole is at the same
radius from the reference center hole and can be used to get the
angles between each hole exact. He will probably need to start with
a small drill bit first and progress up the the actual diameter of
the hole needed otherwise excessive grabbing will occur. I used HSS
drill bits for this operation and they are now all dull. You may also
want to use TIN coated cobalt drill bits.
Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
I have a 18"x 18" x 5/8" of G10 I took to my machinist who can make
about anything. I could use some feed back on machining techniques to pass on.
My first one was (12" x1/2") I made myself. Cutting this is the
first. This one is much more massive and will have 1/2 " tungsten x
2.3 (12) pressed in. The feedback I got earlier was to make the
holes .001 smaller and press the tapered tungsten in. How far from
the edge would be wise? The set screw method directly into the G10
will hold them in place (I hope).
This will be on a variable asrg gap maybe up to 400 bps or > than or so.