[TowerTalk] [Bulk] Re: [Bulk] Re: Grinding hole in thick steel plate?

Grant Saviers grants2 at pacbell.net
Wed Sep 9 12:19:08 EDT 2015


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 at 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
>


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