"Pete C." wrote in message
ster.com...
Bob La Londe wrote:
"Pete C." wrote in message
ster.com...
"Pete C." wrote:
Bob La Londe wrote:
Mostly my mill has been used for engraving, although I've used it to
shape a
few custom pieces. Recently I ran into a problem though. I
starting
cutting some stencils with it. I found milling off a block of wood
flat,
and then securing my sheet to that worked fairly well, but when
working
with
metal I've had a hard time figuring out how to secure the pieces I
want
to
remove. They tend to shift, bind the cutter, and it goes SNAP. On
light
stuff or small jobs I can sit there and watch for it to get close to
going
through and then take a couple tungsten scribes and use them to hold
the
waste piece down until the cutter is done and clear. Still it seems
like
there should be a better way to do that. On a detailed stencil or a
piece
of aluminum sheet I can find myself standing there for quite a
while.
I had
considered pocketing the entire waste piece, but that would really
increase
the time to do a job. Also, Lazy Cam really throws in a lot of
strange
artifacts that need to be manually edited out before you can get a
final
piece. Not horrible if you are doing twenty of something, but the
time
to
get a good piece can be pretty horrible when doing just one of
something.
My latest project is to try and make some commemorative coins for a
local
event among friends, and pocketing out the entire coin is obviously
not
the
best option. LOL. I have pretty much decided to finish one surface
of
the
coin, cut it out, and then drop it into a pocket in my wood block to
do
the
other side. My problem seems to be in finding a way to cut it out
without
having it slide and bind as soon as it starts to come loose from the
stock.
Make an aluminum clamping fixture to hold the coin blank by clamping
the
circumference, i.e. pocket out the hole to size, do a horizontal hole
for a clamping bolt and cut a relief slot so you can tighten it. Cut
the
blanks via another method, like sizing and parting on a lathe. Then
drop
a blank into your fixture, clamp, engrave one side, unclamp, flip,
reclamp and engrave the other side.
Don't forget to include a couple access notches in the fixture to allow
the coin to be removed easily.
When I engraved plates I drilled a hole through the fixture where it
hangs
off the table allowing me to push it up out of the socket with a pencil
eraser.
Yep, or access notches would allow use of tweezers or just a probe to
flip the coin out.
Since I do not have a lathe I am trying to consider other ways to
do this however.
Sounds like an excuse to get one 
Its on my maybe someday list.
You can even use a knurling tool to
put fancy edges on your coins.
That would be cool.
I had certainly considered cutting ing out my coins first.
Atleast that way if one binds and gets damaged atleast I won't have
wasted
all the time on surfacing and engraving.
Find a cheap punch press?
I suppose that is a possibility. Know of anything that will punch a 2" disc
out of sheet aluminum easily and cheaply? I do have a 12 ton hydralic press
with an air operated jack already for other projects. I've got .090 amd
..125 aluminum scraps laying around to play with.
P.S. For another project I engraved a punch of metal core plastic coated
poker chips and it worked out pretty good.
Nifty.