How to cut a 10" round hole in 5mm mild steel?

Apr 22, 2023 Last reply: 3 years ago 66 Replies

I thought a fly cutter was a multi carbide-tipped tool for surfacing using a milling machine, rather than for making holes?

I've got a sort-of tank cutter for making holes in plasterboard ceilings to fit recessed lights (i.e. bigger than downlighters) even that is a bit sketchy to use.

A fly cutter is simply a single cutter on an adjustable radius arm. You can use it to mill or drill

A tank cutter is the same as a hole saw, but generally for metal

Gonna piggyback upthread here...

When using a jigsaw, a piece of wood under the jigsaw base plate can help: with

5mm steel, and the usual jigsaw stroke, there's only a bit of the jigsaw blade being used. Pack a spacer under the jigsaw, perhaps with a slot to guide the blade. This allows using fresh teeth further on down on the blade, so you get more cut length out of one blade before it is dull...

Thomas Prufer

I'm not sure that's worth the effort?

The stroke of the jig-saw will be far more than 5mm (say 15mm stroke?) so the proportion of blade having been used will still be quite high. While you might get a clean few mm of blade after using removing a shim, you'll then be overlapping the heavily used part of the blade too.

I think I would buy an extra blade!

5 mm steel + 15 mm stroke leaves plenty on a blade that has at least 40 mm usable length.

The blade does get more wobbly towards the tip -- and this is a tip for when you don't have an unlimited supply of extra blades.

Thomas Prufer

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