Found a good deal on a heavy steel cabinet. Aprox 7 foot tall, 3 wide and 2 deep. With shelves for cuttings. I plan on having 4 inch vents for fans and/or future hood vents.

Can anyone share tips on cutting the holes? How did you cut yours? A Greenlee hydrolic knockout is $45 to rent, more than I paid for the cabinet but probably the best option for an easy clean circle. Has anyone tried a hole saw? A jig/sawzall? should I just rent the knockout? Also any advice on the hole size is appreciated. Am I right in thinking 4 inch?

Thank You!

So your asking how to cut a hole into a wood box? lol if you are, im sure you can find some tools around to get it in a hole-ish shape

No I'm asking how to best cut a 4 inch hole in a STEEL, AND if 4 inch would be the way to go. 4 inch may be overkill for a cabinet of this size. Currently it will house CFL's but I would like to upgrade to HID in the future and it appears the smallest vent fittings are all 4 inch.

Only someone who is concerned with quality and has successfully cut a 4 inch hole (a perfect circle) in steel will appreciate this question. I don't see it as a breeze myself and I don't want it to look like shit when it's done.

Steel cabs are a pain in the ass, thats what I have and I wish it was wood lol, Ive been needing to fix my vent holes making them bigger but its such a pain to cut the damn holes I have left them the way they are for over two years now.
I use a dremmel tool and cut square holes last time, I have no idea how you would cut a circle hole in steel, Im sure there is a way and ill love to know as well, good post.

You can buy 4 inch hole drill bits at the depot, I bought one to drill through a fridge, not exactly the same but it did work

Nice and clean

They're called hole saws...you can get them up to 6" diameter. If you've never seen or heard of them before just go to home depot and ask for a hole saw for steel. Fuck even one for wood would cut through sheet metal but it won't last very long...

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"If it fucks, floats or flys. Its cheaper to rent it!!"

instead of cutting one large hole, mark out the area and drill lotsa little holes. or drill them all close together round marked out circumfrence and knock it out. doh! lol

Dura72 good idea with drilling little holes, I hadn't thought of that.

Yes I've used holesaws, just nothing close to 4 inch and never in steel. Also I don't know what happens when the holesaw is almost finished with the cut and binds up. This has happened to me before with large drill bits and its a show stopper for sure. If the panel of the cabinet came off I would use a drill press but it doesn't. Home Depot wants $33 for the holesaw and the pilot bit for it. Can I cut 3 or 4 holes in steel with one saw or will it wear out after the first cut? Anyone who has used a knockout knows how slick these work. I think I will rent a knockout set instead. I will be able to make as many 4 inch holes as I need without running into any mishaps and the same kit can punch out my smaller holes for the electric also.

Thanks everyone for your advice.

id ay jus get the knockout if u want it perfect

circular hole-saw £7 from argos i use the 102mm one for a passive in take at the bottom and a 4"in_line fan to the out take at the top, there are 5 sizes in the kit its made by a crap make 'challange but for 2 holes it works perfectly