Need to cut a nice round 4" diameter hole in the end of steel barrels.

[PILOON]

Hole saw works just fine BUT after the 1/4" pilot hole is drilled replace the bit with a plain 1/4" rod as otherwise the pilot hole will grow and you will end up with a very messy 4" hole with sharp jagged edges.

 

[medic0648]

Plasma cutter or torch with a circle attachment works great also.

 

[cisco]

Yup, hole saw is an economical option that cuts a nicely shaped circle if, as noted above, one changes out the drill for the pilot hole with a plain rod once the metal is penetrated. However, also as noted it makes a major racket (use hearing protectors) and oil helps (so it's also messy). I recently made a "trailer septic" for my small travel trailer that spends the hunting season at a club (drum with 2 holes, one for inlet and other outlet to 4" peanut-expanded, wrapped drainage tubing). Yeah, I used thick plastic 55 gal drums, but the principle, and the hole saw, is the same.

 

[Birdhunter1]

Lenox 4" hole saw on a heavy duty low speed drill works well. Like others have said keep it oiled. I have a 1 1/4" Lenox that you'd be hard pressed to tell it had cut anything but 1/4" paneling and I've probably used it for 50 holes in 1/4" mild steel.

 

[CurlyDave]

Hole saw works just fine BUT after the 1/4" pilot hole is drilled replace the bit with a plain 1/4" rod as otherwise the pilot hole will grow and you will end up with a very messy 4" hole with sharp jagged edges.

This is actually the way any good machinist will use a hole saw, and is in the directions for the higher quality saws.

To make it even easier, I recognized long ago that there is no need for the pilot hole to be drilled by a drill bit mounted in the center of the hole saw. I use a plain old 1/4" drill bit to drill the pilot hole and then switch to my hole saw which has a permanently mounted 1/4" solid rod in the center.

 

[EddieWalker]

Lenox 4" hole saw on a heavy duty low speed drill works well. Like others have said keep it oiled. I have a 1 1/4" Lenox that you'd be hard pressed to tell it had cut anything but 1/4" paneling and I've probably used it for 50 holes in 1/4" mild steel.

I also recommend going with Lennox, which is sold at Lowes. I have a 4 inch that I use for light fixtures all the time, but we ruined it drilling 4 inch holes in Hardi siding. It's a miserable tool to work with because of how it randomly binds up and wants to twist the drill out of your hand. I have a half inch corded drill with a ton of power, but I'm afraid to use it for drilling with the hole saw because of the binding issues. I use my Makita cordless drill for this with the handle on it and even with that, it's still a battle.

If this is something you do all the time, that hole punch might be a worthwhile expense.

Eddie

 

[PRF]

Plasma cutter would be so fast if you have access to one.

 

[CurlyDave]

I also recommend going with Lennox, which is sold at Lowes. I have a 4 inch that I use for light fixtures all the time, but we ruined it drilling 4 inch holes in Hardi siding. It's a miserable tool to work with because of how it randomly binds up and wants to twist the drill out of your hand. I have a half inch corded drill with a ton of power, but I'm afraid to use it for drilling with the hole saw because of the binding issues. I use my Makita cordless drill for this with the handle on it and even with that, it's still a battle.

If this is something you do all the time, that hole punch might be a worthwhile expense.

Eddie

The right tool for large hole saws is a Milwaukee HoleHawg. Not cheap, but I have never had anything try to rip the drill out of my hand.

 

[Brad_Blazer]

Hydraulic Punch Driver w/ 5 Hydraulic Punches & Dies
You'll have to add the 4" punch.

 

[SPIKER]

I've had some Milwaukee's ripped out of my hands more than once, heck probably 50+ times... TOO much power most of the times, using big hole saws I prefer a 3/8" old B&D or Dewalt something with enough power but not enough to twist your wrist off your arms.

M