Can somebody give me some advice here?
I have two left hands and I need to drill a 12cm diameter hole in a steel plate about 1mm thick (the top cover of a computer case).
The top of the case has black enamel laquer and it would be nice if I could do it with minimum damage to that and as neatly as possible.
What would the experts do here, and what tools do I need? Are there maybe even places that do things like that for you for a small fee?
TIA, David
clamp the job between 2 bits of ply and drill it with a 12mm drill, remove plywood, finish off with a rat tail file, job done
RT
That'd work fine for a 12 /mm/ hole...
For the OP - a bimetal hole saw will do a pretty good job:
You'll get a better finish if you clamp ply both sides as per the above suggestion.
=============== I do mine with a jigsaw with metal cutting blade. I use masking tape to hold thin card around the cutting area to prevent scratching. If you can't do it yourself ask your friendly DIY neighbour to do it for you. It's only a 5 minute job and it's really not difficult. Alternatively since you've asked in a DIY group why not take the plunge and buy your own jigsaw so that you'll be ready to do the job next time you need to do it?
Cic.
A 120mm artillery piece is what you need. One bang, job done.
persons of a certain age used to use sheet metal hole cutters for radio chassis:
However, it's harder to screw up. Take a nail and hammer. Punch the case at the point you want each 10mm (or so) hole. Drill a 3mm hole. Repeat with a 10mm drill. Now, go around the edge with wiresnips, snipping the bits off, then file. If you use the file in the right way (only press down when it's cutting down past the varnish, you may not even flake any off.
When I wanted a fan hole in a case (I was upgrading for a friend and he wanted to keep the original desktop case, as he had had shelving built specially to fit it), I used 15" G clamps to hold the case onto a thick block of wood on the table of a pillar drill. I then cut the hole with a fly cutter at 300 rpm.
Ear defenders are recommended (it screeches a lot, even with lubrication). High impact eye protection is essential when using a fly cutter, even at low speed.
Colin Bignell
Why not just use aviation tinsnips?
ahem..... erm ... Jigsaw, I meant Jigsaw :p
RT
The normal way of 'drilling' a large hole in such thin plate like thi
is to use a die, this come in two pieces that are clamped togethe slowly with a screw thread.
Phone round some sheet metal engineering places to see if they hav such a die, if they do they may be able to help. Obviously, the di needs to be the right diameter.
I think most laser cutting places can only work with flat sheet, bu its worth a ring round, if they can cut a formed piece, then all the need is a drawing.
The same goes for CNC punches.
If you want to go more DIY, then mark out your hole with a pencil, the drill a series of small holes round it with a good drill bit, do thi well inside of the line. Then use a hacksaw blade to join the hole up. Buy what is called a nibbler - you can get air, electric or han ones, these bite tiny slithers of metal in thin sheet. Use this t get as close to the line as you dare.
Then finish the job carefully with a reasonably fine file.
If you drag the file along the edge as you finish, it will remove an burrs.
If before starting the job you cover the rest of the shell i insulation tape, masking tape or sticky plastic film, you'll preven any accidental scratches.
That is unless you plan to spray paint it once its complete.
I would argue, though, for the cost of a PC case, can't you get a ne one that has the holes in the right place? It would probably cost les than any machining and/or tools.
Regards, Jason
-- the-moog
No expert me, but I'd try a nibbler, like this:
Your steel might be a bit thick, I don't know.
You need to drill a 10mm hole to start with, near the edge of your eventual hole, but not so close that you risk marking past the edge of the hole. Cover the area with masking tape first, to protect the surface and make it easy to draw your guide line on.
You'll find those nibblers handy for cutting all sorts of shapes in sheet metal and plastic.
Mike Barnes wrote :-
You can also get a power version that fits in an electric drill, got mine from Machine Mart about £15 iirc, it cuts car body panels so should do pc cases.
Regards Jeff
I doubt the OP has them.
Take it to an electrical panel builders and ask them to punch the size of the hole you require. They have hydraulic punches that will do the job in 'jig' time. They can punch holes up to 3mm in steel, 1.5mm in stainless. They will probably charge you a nominal amount. Alternatively a commercial kitchen fabricator would be able to do it for you.
For small holes like B7G and B9A yes, but for anything larger I couldn't afford Q-max punches and used to use my dad's old tank cutter - the type you used in a hand brace. Slow, but it produced nice neat round holes requiring a minimum of de-burring.
A quick Google shows that adjustable tank cutters are still available, so there's another option for the OP (if you can find one that adjusts-up big enough). Use of the Abrafile is another possibility.
Put two or three layers of masking tape on the case to prevent scratching. Mark out the hole with a compass, and drill a small hole inside the circle large enough to pass a jigsaw blade through. Then carefully cut round the inside of the line using a jigsaw fitted with a metal cutting blade. Finish off with a half round file then remove the masking tape.
I wouldn't try doing it with a fly cutter as this can be very dangerous unless you know exactly what you are doing.
Probably quicker and/or cheaper to go out and buy some than use some of the methods that people are recommending. At least I don't think anyone's mentioned Dremels yet.
Works well. Carbide router bit, MDF guide.
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