On Sep 15, 3:30 pm, "DoN. Nichols" wrote:
On 2008-09-15, trg-s338 wrote:

Newbie here with perhaps a basic basic question. Need to grove a
circle in a custom aluminum mounting plate for a C-face motor with a
protruding locating ring cast into the motor face. Don't have a mill
to do coordinate locating so I've drilled an exact sized hole for the
motor shaft and hope to mark the motor ring onto my mounting plate
directly with some sort of transfer ink such as that of a rubber stamp
pad but I don't know of such a compound to use.

To mark, take a wide point blue Magic Marker (or similar) and
color the whole zone near where you expect the groove to be and past.

Then put the motor in until the ring is in contact, and rotate
the motor a turn or two to rub off the marking where the groove should
be.

I then plan on using
my small rotary table and heavy duty drill press to grove the mark on
the plate (a depth of about an eigth of an inch) with an endmill I
purchased that corresponds to the the motor face ring in size. Does
this approach make sense,

No! Attempting to mill with a drill press is dangerous. The
chuck is normally mounted via a taper -- which is great for axial forces
like those encountered in drilling, but very bad with lateral forces
such as encountered in milling. What is likely to happen is that the
chuck will disconnect from the taper while still spinning at high speed
(the size of the mill is pretty small I think, from what else you have
said, which would call for high speeds). That spinning chuck with the
sharp milling cutter will then bounce all over the shop, perhaps chasing
you around the shop -- except that it will move faster than you can.

You say that you don't have a mill. Do you have a lathe? One
large enough to mount the motor mount plate onto a faceplate (or to hold
it in a 4-jaw chuck) and *turn* the groove -- with a bit ground for
trepaning.

or is there another way. Is there such a
transfer compound or prussian blue with some viscuosity to effect a
good transfer mark? I suppose I could use a compass but I need it to
be precisely right on.

You also need a better tool than a milling cutter in a drill
press to do this.

Any suggestions? Thanks.

Find someone with a milling machine or a lathe to help you.

Good Luck,
DoN.

--
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Thanks for reiterating the risk in using the drill press as a mill. I
agree that doing this can be clearly dangerous. I just thought that
since the grove I'm trying to cut is only about a sixteenth of an inch
wide and perhaps less than an eighth deep, the stresses involve might
be acceptable. Your ideas about spinning the C-face onto the "blued"
plate to make the mark is self-evident although I don't know why I
didn't think of it. Dohh!

I suppose I could also just chuck a lathe tool bit of the appropriate
ground to width and lock the drill spindle and just carefully rotate
the rotary table while feeding lightly and incrementally until I
achieve the proper depth. I do have a lathe but it is non-operational
right now until I get it located and hooked up to my RPC in the garage
to power it up. In the meanwhile, I am looking for the easiest,
cheapest, and safe way to do this one time job with minimal fuss.
Thanks for all your input, you might have saved me from an endmill in
the eye scenario.

Manny
trg-s338