"Karl Townsend" wrote in message
...
I was using the radial arm drill this afternoon to drill a couple 3/4
holes in 1/2 inch plate. I needed to copy the hole spacing on a part
I'd ruined so I clamped it to the plate with a couple vice grips. Then
in the drill vice and drill the hole in one shot. The drill grabbed
right when busting through and the part pulled right out of the vice
and turned into a helicopter.

I'm glad the vice was as high as it was, I just got a nasty bruise on
my belly. If it had been a few inches lower, I'd be a soprano right
now.



Make sure the edges you are clamping in the vise are parallel to each other,
mill one or both of them, if needed--most vises, especially the Kurt style,
don't clamp securely for instance to bandsawn edges, where basically you
only end up putting pressure onto one end of the part...

Also, it's oftentimes hard enough to "let up on the handle" in order keep
the drill from "grabbing" when it starts to break through as it is; this
situation gets severely compounded if your workpiece deflects downward from
quill thrust, because when the drill finally does break through, the
workpiece wants to spring back upwards at about the same time which only
worsens the situation...

For this reason, whenever drilling plate or sheet materials, it's also good
idea to put some sort of support underneath, at a point near to where you
are drilling the actual hole.

Thankfully, things didn't turn out worse...