Charlie,
The proposed "move the hole 0.25"" application of a hole saw would have
it cutting only on one circular segment of the work, so the center stub
on the hole saw is undergoing a +/- something stress reversal of bending
every rotation. In my segment sawing try the hub fatigued and broke,
which was a very logical result in retrospect. I was using a high
quality US brand bi-metal saw about 3" in diameter. For a smaller
diameter saw the peak to peak stress cycle would be less so the saw hub
might not fail from fatigue. For a full circle cut, there should be no
bending of the hub when using a drill press.
Another way to manage the chip buildup in a 360 degree hole saw slot is
to drill 2 to 4 thru holes just inside the od of the saw kerf so the
chips can be pushed out to the backside of the work, so it needs to be
clear. For sawing a segment that is not needed as the swarf will mostly
clear itself.
Grant KZ1W
On 9/8/2015 16:35 PM, n0tt1@juno.com wrote:
Grant,
A "hole saw" would be useless in 3/4" thick steel plate and without a
pilot drill center just wouldn't work no matter how rigid the setup.
I don't agree with all of that. I had no trouble sawing through 5/8" hot
rolled
steel and could have easily sawed though a thicker piece if I needed
to. It took about 15-20 minutes per hole.
Yes, a center pilot is needed *or* at least
have another "thick" piece of metal pre-drilled to use as a guide.
Use plenty of oil, remove chips as they accumulate and don't
"push it". Let the hole saw do the work. Use a drill press! Use
a sharp bi-metal hole saw....no cheap stuff!!
73,
Charlie, N0TT
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|