You can spend a lot of money on hole saws and still come out with a crude,
over size hole in sheet metal. The problem is the arbor they come with.
Too much slop.

I found a solution if you have a lathe.
Screw in a 5/8th fine thread bolt and nut.
Turn it around and chuck the hole saw itself. Then turn the
5/8th bolt threads down to make it run true.

Paul Lamar

I nearly broke a wrist and an ankle the other day trying to cut a 2"
diameter in the side of a 6" well casing, 6' underground (I was crammed
down into the bottom of a trench when trying to cut the hole).

I started out with a Morse hole-saw. It looked good but was a piece of
crap. I drilled a pilot hole first, then broke 5 pilot-bits trying to
get the a decent start on the 2" hole.  I finally switched to an old
somewhat dull Milwaukee hole-saw I had around and managed to get the job
mostly done.  Once I had the hole almost finished I switched back to the
much sharper Morse.  The saw jumped out of the hole, wrapped up my
shoe-laces in the drill, tried redesigning my arm so the elbow pointed
upward, and then ripped up the canvas shoe I was wearing.  That was two
weeks ago and I still have a big welt/bruise on my ankle.
I am picking up some Milwaukee blades first chance I get.  If Hilti
makes hole saws, I suspect they'd be great too.

RBerglund

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