Drilling ~1mm thick steel case metal

[lost eden]

Thanks for all the advice guys. My power drill is very old (the chuck says 'Made in West Germany') so it only has 1 speed & isn't particularly useful for anything that doesn't want full speed (I end up 'pulsing' it on & off for certain materials). It was okay with the aluminium, drilling through a drop of water to keep the bit cool & stop the shavings from going everywhere.

Originally Posted by nigelwright7557

I tend towards switches jack plugs etc that require round holes then buy sheet metal punches. This is will give a good finish without any sharp edges.

Yep, I was already planning on only using circular parts, even going so far as having a hardwired mains cable (with strain relief grommet etc.) rather than trying to make a rectangular hole for an IEC socket. I haven't come across sheet metal punches before, how easily will one go through 1mm SECC? If I do it right I can get away with just buying 1 size.

I've asked my university's physics department if one of their workshop technicians would be willing to drill for me (health & safety won't let me use their equipment) but if they come back negative I think I'll look at getting a punch. Seems less likely to go wrong!

The case is completely dismantleable (it came flat-pack) so a good working position isn't an issue.

[ODougbo]

Punch or step drill, a fellow at work found out the hard way using a standard twist drill bit. The metal caught, jumped up and cut his hand (not seriously).

[overtheairbroadcast]

Originally Posted by lost eden

I've just bought a nice big 3U rackmount case to mount a pair of LM3886 monoblocks in & I need advice in how to make some holes in the case for sockets/switches/etc.

As far as I can tell the metal is 1mm thick steel. I have a set of 'high speed steel twist' drillbits & an old 350W 3100rpm power drill. This combination worked nicely for drilling the thick aluminium you see in the picture but I'm not certain how well it will work against steel, particularly so thin. Do I stand a chance or will the drill completely mess up the enclosure?

I also have a Dremel, which can't take thick enough bits but probably runs slower than 3100rpm at its lowest setting so might be useful for making pilot holes?

Any advice? I don't want to mess up a case I just spent £65 on...

Wow, a thread I can actually give advice on! As a newbie here, this is neat...

Anyway, I have drilled a lot of holes into a lot of different metals (sadly, not a hobby). Stainless steel sinks, aluminum plate (6061 T6), copper plate, sheet metal, and mild steel plate. And tubing and pipes.

The one thing that I learned early on is that even with a good punch, twist bits tend to "skate" all over the place (scratches = no good) and to make matters worse they "bounce" around in the hole giving you an oblong hole.

This is what you need.

Unibit Step Drills - Drill Bits - Tools - IRWIN TOOLS

Step drills. I bought a set of three on sale ($20 CND when it was 66% off) and bought one very good one for $27 for aluminum and copper. The steel tends to wear them fast. I have used them in a drill press on the odd occassion, but most of the time I use them in a portable drill driver. I also use cutting oil and go slowly to start, but never go full blast on it (wear on the bit). Slow like a 45 rpm record (yeah no kidding) actually works nicely. I still use a punch, but only to make a small dimple.

The great thing is that each step is a defined width listed on the flat side of the drill bit. I mark which one I want with a marker mark if I am do a lot of the same sized hole. Good practice is soft backing like solid styrofoam or scrap wood, clamping down good and hard with non marring clamps, and go to the races.

Trust me, this is the best round hole maker you can get with a drill. And you can try it on scrap.

Enjoy!

[doctordata]

Place a small piece of polishing cloth or old Tshirt soaked in oil water mix under the drill and you get perfect round holes .

Rens

[jitter]

Originally Posted by lost eden

As far as I can tell the metal is 1mm thick steel. I have a set of 'high speed steel twist' drillbits & an old 350W 3100rpm power drill. This combination worked nicely for drilling the thick aluminium you see in the picture but I'm not certain how well it will work against steel, particularly so thin. Do I stand a chance or will the drill completely mess up the enclosure?

Any advice? I don't want to mess up a case I just spent £65 on...

Then spend some more on good tools first.

Of the advice given so far, the step drill would be my favourite, esp. when limited to using a handheld drill. I use a taper drill for holes bigger than 10 mm.
But you will have to buy a drill with viarable speed first as these step or taper drills need to be used at low revs.

For rectangular holes: a fretsaw (with lots of spare fine teethed blades, these things break easily) and files. I use the fretsaw to roughly saw out the big part first and then file the rest down to get a reasonably rectangular shape. Doesn't need to be perfect as the bezel will cover it.