Using a hole saw in a magnetic drilling machine

[Christopher Tidy]

Hi all,

I talked to a guy this morning who suggested using a hole saw in a
magnetic drilling machine. I need to cut some round holes between 2" and
3" diameter in 1/4" mild steel plate. The guy said I should be okay
buying a smaller drilling machine with a broach capacity of 32 mm and
using a hole saw to cut larger holes in 1/4" plate, rather than spending
more on a big machine. I assume the saw arbor is held in a Jacob's chuck
adaptor. Does anyone have experience of doing this? Does it work okay?
Thoughts would be appreciated...

Best wishes,

Chris

[Robert Swinney]

Hole saws come in all sizes up to around 4 or 5 inches. They are held in a
Jacob's chuck. Run the saw at a slow speed; chosing speed to suit diameter
from a single-point (lathe) speed chart. The saw will choke on it's chips,
therefore it is necessary to frequently lift the saw to evacuate chips. Use
cutting oil, liberally. I recently cut a 4-1/2 diameter hole with a hole
saw in a piece of 3/4 inch mild steel. It took a long time; upwards to 30
minutes as I recall. A lot of the time was "wasted" in chip removal. It
cut a nice hole. The chip removal problem can be alleviated, somewhat, by
drilling 2 or 3 relief holes, say 1/4 inch, around the path of the hole saw
at the edges to allow the chips to fall through.

Bob Swinney

"Christopher Tidy" > wrote in message
...
> Hi all,
>
> I talked to a guy this morning who suggested using a hole saw in a
> magnetic drilling machine. I need to cut some round holes between 2" and
> 3" diameter in 1/4" mild steel plate. The guy said I should be okay buying
> a smaller drilling machine with a broach capacity of 32 mm and using a
> hole saw to cut larger holes in 1/4" plate, rather than spending more on a
> big machine. I assume the saw arbor is held in a Jacob's chuck adaptor.
> Does anyone have experience of doing this? Does it work okay? Thoughts
> would be appreciated...
>
> Best wishes,
>
> Chris
>

[Karl Townsend]

"Robert Swinney" > wrote in message

....

Good from Robert advice here.

I prefer using lots of water soluable coolant to oil, just because I hate
the oil mess. Oil probably is better for the cutting edges though. I'll add
that a hole saw tends to give a rough edge and be oversized. If you need a
good accurate hole with nice finish, look at rotabroach.

Karl

[Christopher Tidy]

Karl Townsend wrote:
> "Robert Swinney" > wrote in message
>
> ...
>
> Good from Robert advice here.
>
> I prefer using lots of water soluable coolant to oil, just because I hate
> the oil mess. Oil probably is better for the cutting edges though. I'll add
> that a hole saw tends to give a rough edge and be oversized. If you need a
> good accurate hole with nice finish, look at rotabroach.
>
> Karl

Thanks for the advice. The holes are for dials and switches, so they
don't need to be extremely precise - it sounds like a hole saw would do
the job. But for maximum flexibility I might be better looking for a
magnetic drill with, say, a 50 mm broach capacity. The selection on eBay
is pretty poor, and I'm always reluctant to buy more expensive items on
eBay anyway. Sadly eBay won't provide you with a member's address
anymore, even when you've conducted a transaction with them in the past,
and I think that shelters bad sellers. Keep on looking I guess...

Chris