I need to make a 5" round hole in the back of a brand new table saw cabinet. I don't have a regular hole saw,but have one of those adjusable ones that has a 1/8" tool bit in the end of the arm. The metal that I am cutting through is about 1/16" steel. I have a jigsaw but figured this might cut a neater hole? any input? keith
Suggest you lay tablesaw in such a manner that surface you want hole in is horizontal, then drill couple of 1/4 inch diameter holes on inside periphery of your desired hole, and have at it with jig saw. Take your time, and be prepared to go through a couple of blades. I like to glue a piece of paper on surface, then scribe circle with regular compass.
Carefully staying on inside (or outside) of scribed circle will give pretty neat hole. Smooth it up with a sanding drum in your hand drill.
A variable speed jigsaw set to the lowest speed is going to be a lot safer than a 5" hole saw and incredibly safer than a fly-cutter. An alternative, if you know an electrician with a really good set of punches would be a 5" chassis punch.
I installed my own 3 phase service in the shop, including mounting the CT can and cutting needed holes for TA fittings in various steel cabinets, which I gather would be much like your saw cabinet. Considering I had nothing but the type cutter you describe, and a ½" VSR drill motor to accomplish the task, I ground what would best be described as a somewhat narrow parting tool, short, with a lead on the cutting edge such that it cut deeper at the outside edge so it would not leave anything in the hole when the center come out.
As long as you can keep a portion of the shank in the ¼" drilled center hole, you'll be pleasantly surprised that you can fly cut the holes with little difficulty. Run your drill quite slowly, don't apply too much pressure, and more or less let the setup sort of pivot about center. Keep an eye on where you need to cut, for it will likely break through on one place, so you sort of have to encourage it to cut where there is more material and ignore places that have cut through. When you break through in various places, I found it was smart to stop and simply break out the remainder of the piece with a hammer. By then it comes out very easily, and prevents you from breaking the tool when the center comes out.
I have flycut several holes in this manner with outstanding success. You may have to regrind a tool or two because you get heavy handed and break them, but otherwise it works very well. Far better than a hole saw, which generally cuts almost any sized hole but the one you want.
I don't know of many electricians with a 5" KO punch ... even if you got hold of on it would be about 5.5" because that's about the OD of 5" conduit. I never ran anything over 4" but if you punch anything over 2" you need a hydraulic set. If you tried to pull a 5" using a wrench it would have to be at least 20" long ... then you would turn the band saw over the first turn you made. Spend the money and buy the Hole saw ... if it's to much then rent it
We don't know how thick the metal is -- or what metal (though steel is pretty likely, and I suspect something like perhaps 20 ga -- unless it is structural as well.
And I've punched 3"+ holes in the bottom of a relay rack cabinet with a knockout punch and a 1/2" drive ratchet wrench set. Not fun, but it can be done. This was with the ball thrust bearing drive screw, not the plain bolt, which made it a bit easier.
And the rack had only two PCs in it -- plus about twenty very small (U.S. Robotics) modems, so there wasn't much mass there.
If the hole is in a vertical panel (as I believe was the case), a ratchet would do the job -- just orient it to apply force downward and you are unlikely to topple the bandsaw. With an open-end or a box wrench you would have to keep taking it off and repositioning it to keep the handle close to horizontal, but with a ratchet, you are fine.
Granted, hydraulics are nicer -- but they are not absolutely necessary.
I go with what Harold said, except substitute the center drill for a piece of round stock to run in a pre-drilled hole. This works better on either a fly cutter or on a hole saw. It helps prevent side wandering. Wear ear plugs, the screeching is hell.
Yep, what RJ said. That's why I suggested that at least a portion of the shank of the drill be used in the hole. A piece of stock in place of the drill shank guarantees success. To insure longevity, a dowel pin or piece of drill blank is even better.