Using a hole saw in a magnetic drilling machine

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

Best wishes,

Chris

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

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

I have used a 1 1/2" diameter bimetal hole saw in a drill press to cut hundreds of lightening holes in 1x2x1/16" wall rectangular aluminum tubing. Makes noise and chips like you wouldn't believe, but it's faster and cheaper than a fly cutter or just about any other metal. Another aspect not mentioned above is that as the cutter heats up from friction it will expand and bind in the hole. It is necessary to keep the cutter fairly cool to prevent this from happening. I had another person squirting oil and compressed air on the cutter to remove chips and help hold the long piece of tubing while I aligned the hole saw for each hole and ran the drill press. The compressed air helped cool the tubing and remove chips.

I've cut a few 4" conduit holes in industrial control boxes with a Starrett hole saw in a large Milwaukee D-handle drill. The holes were in side walls so chip clearance was no problem. I had to wedge myself against the opposite wall of the enclosure to get enough force on the hole saw to make it cut well, and whenever the saw grabbed the handles were guaranteed to make a quarter revolution while the motor coasted to a stop, regardless of which part of me was in the way.

jw

...

LOL, Been there, Done that.

Karl