I have a drill press with speeds ranging from fast to escape velocity. I've given up on
hole saws, and admit that I've gone back to drilling several 3/8" holes around the
periphery, joining them with a jigsaw, and finishing up with a file.
The last picture on my 4CX100A amp page
<http://www.qsl.net/k2vco/4CX1000A/K2VCO%204CX1000A%20Amplifier.html>
shows a panel with some meter holes made with this method.
On 9/13/2013 5:24 AM, Jim Garland wrote:
My least favorite part of homebrewing an amplifier is making the meter
cutouts and tube socket holes. Last evening I cut three 2.90 holes for
GU-74Bs and survived the experience. I have a set of hole saws, but not
metric ones for Russian tubes, and therefore had to use a fly-cutter. IMHO,
fly-cutters are the most dangerous tool in a workshop. I hate the things. I
securely clamped the sheet aluminum stockl to the bed of a large
(floor-mounted) drill press, set the drill press on its slowest speed, and
used aluminum cutting fluid. One has to advance the fly-cutter VERY slowly
to prevent the cutting tool from grabbing the aluminum. If that happens, the
sheet aluminum is likely to go flying around in a big circle like a sythe.
The other danger is absent-mindedness, which can lead the drill press
operator to reach in with his fingers to remove a piece of aluminum debris.
Fly-cutters should never be used with a hand drill, as I stupidly tried once
as a teen-ager. They absolutely require a large floor-mounted drill press
with a sizeable bed.
73,
Jim Garland W8ZR
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Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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