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You may actually want to go to a less
aggressive cutter unless you are really hogging out heavy sections. Those open,
low helix aluminum cutters are intended for gouging out hunks of welds and
castings, not shaping sheet metal. The nearly straight cutting edges tend to
bounce around a lot unless you are REALLY getting on it... hard enough to limit
speed with loading while holding the throttle wide open. They make finer toothed
versions that are also suitable for aluminum.
As for speed, run it wide open. The
drilling surface speed for aluminum is about 350ft/min, but milling speeds of
1000ft/min are common with multi-flute cutters. You can easily double that with
carbide. It's only too fast if it burns up the cutter (which isn't going to
happen). In drilling, the heat is concentrated by the surrounding material...
not a factor with a die grinder.
Feed against the rotation. Feeding with the
rotation is just begging it to grab and run.
Try to get your hand as stable as possible,
because what you are experiencing is the same as chatter in a machine tool,
caused by too much slop or a flexible setup (doesn't get much more flexible than
a hand held die grinder). If all else fails, get one of these "Super Cut" vixen
files (they make both flat and half-round). I have found them to be as fast as a
die grinder in many situations. They don't jump, are quiet, and are far more
controllable. Mike C.
----- Original Message -----
Sent: Monday, February 23, 2004 4:31
PM
Subject: [FlyRotary] die grinders
despite already building a -6a I still have
problems with the die grinder. I have yet to figure out what makes it
jump around and what makes it cut nicely. I am using the very open tooth
die that won't clog up when cutting AL. what is the correct feed
direction, speed, etc... I should be trying?
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