Home howto - fine cutting sheet steel but not from the edge

[Rich Jordan]

If I have a plate of sheet steel, probably 16 or 18 gauge (for computer bracketry), is there a good home shop mechanic way to cut patterns in the steel away from the edges? I need relatively fine cuts (minimum kerf) so I can bend up mounting tabs that have room for one or more mounting holes, about 1-1/2 inches in from the plate edge. No water jet, no plasma cutter, and the metal plate needs to stay flat.

What I'm trying to do is make one of these but with the tabs and mount holes exactly where I need them (which is not where the manufacturers put them). I can use my vise and/or shop press as a brake to bend up the sides, but how to cut the mounting tabs cleanly elude me.

I did try a cutting wheel in a Dremel, but they _suck_ for cutting into flat steel (it takes forever and burns up the disks quickly).

I could actually work with one of these that I have, just flip it around and there's enough meat to cut and fold up a new set of tabs, side bends already in place. Saves making the bends and the sides will help stiffen the flat at least in the one direction.

Thanks!

[Denis]

I would get a nice flat piece of MDF or OSB board and use spray-can adhesive (double-sided sticky tape might also work) to attach the sheet metal to it. Pierce a hole somewhere convenient with a drill. Starting from that hole, use an electric jigsaw with a slightly coarse metalwork blade (or a metal/wood blade) to cut out the shapes you want. For really fiddly shapes, use a manual jigsaw or a jeweller's saw. The board will stiffen the metal enough so it doesn't flop around. Afterwards, heat the metal with a heat-gun or a gas torch to release the adhesive and separate the part from the wood backing.

[Netpackrat]

What Denis said is very close to what I would do, and have done.

[Catbird]

+1

The above suggestion is your best bet without investing in specialty tools. Your only other options are to job it out to a shop equiped with an appropriate water/laser/plasma cutter or get yourself a nibbler: air powered or electric.

[McClarkus]

Does it need to be pretty? Harbor freight sells an angle grinder / cutter for 15 bucks.

[Catbird]

Another way to do it is to carefully lay out where you want your cutouts, set the inside radius of your corners with a chassis punch, and connect the outside diameters of the holes with a dremel cut-off wheel. Clean up the edges with a file.