I'm working on a case design. There is rectangular switch. I am trying to open a rectangular hole on the metallic case to fix it in there. I'm not doing a good job, if it goes on like this it looks like I'm going to ruin the case at all.
How do I open this hole?
Picture #1
Picture #2
Dimensions of the rectangle is 20.0mm x 25.4mm.
There is the tool exactly for this, named nibbler. They sell it for $10 in Radioshack.
Specialized hole punch for specific shapes:
For most advanced holes there is a special drill even
You are doing fine. If you don't have an expensive punch, or even a nibbler, you can do a perfectly acceptable job with a drill and file. I have done many cutouts like this.
The secret is patience. Start each dilled hole in an indentation made by a pin punch so that the drill bit does not wander, and don't try to drill right up to your line. One of the first exercises I did as an apprentice machinist was to file something to within 0.001 inch tolerance. It's not as hard as you may think, but it can't be rushed. Use a good file and clean it from time to time with a file card. Aluminum in particular, being soft, will tend to gum it up.
You'll note that the switch has a flanged edge. Any slight imperfections in your hole (perhaps up to 1 mm, but you can do MUCH better than that) will be covered by this if your original layout lines are good and you are careful not to make the hole any larger than it needs to be.
I installed a very similar switch (single not dual) into an Altoids tin. I used a Dremel with a cutoff wheel. Very easy, it took two minutes.
As always, it's all about having the right tool for the job. Without tools it's impossible, and with better and better tools, it becomes easier and easier.
You're not doing badly so far, but you seem to have drilled some of the holes quite far from the line. That didn't help.
Option 1. Keep drilling, preferably with holes nearer the line. Use side cutters to damage the metal between the holes, then man-handle the metal out with a screwdriver and / or hammer.
Clamp your panel upright in a vice, and use a coarse file to square up the hole.
Option 2. Drill a large hole at two opposite corners, and use a small saw blade to cut each edge. Then file it to shape.
Option 3. Use a dremel with circular cutting disc, then file to shape.
Option 4. If you want to spend some money on tools, you can do a lovely job with a hand operated milling machine. You can get nice little ones on eBay for a few hundred bucks.
Depending on how perfectionist you are, this way it will take somewhere between a long time and a very long time.
I would have my front panel made by a service like Front Panel Express. With hobbyist tools you can't get the same quality and accuracy. (I noticed your fixing hole is off center.) They can work with aluminium up to 10 mm thick, or acrylic or a custom material. You can download a front panel designer software from their site to create your design.
(Disclaimer: I'm not affiliated with FPE)
I agree that a jig saw is the best method if the panel allows the frame to swing, and I recommend the type in the picture, with an adjustable frame, rather than one that has to be squeezed to tension the blade -- I find that type very difficult to control. This one is easy as you can undo the wing nut and shorten the frame, loosen the clamp screws and insert and clamp the blade, then extend the frame and tighten the screw.
Drill a small hole, just big enough for the blade, in each corner, so that you can turn the blade easily for the next side.
I would have went for:
good luck and enjoy it!
