Front Panel Design/Work

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Front Panel Design/Work

Post by jsteinhilper » Tue Apr 30, 2013 12:12 pm

There's a couple tips I would offer on front panel design, or work. (most work, since I can't design squat)

When you're drilling holes, use a "step drill" like "Unibit" or maybe Greenlee. I can attest to the Unibit type, but haven't used the Greenlee bits. With Unibit, you get a nice round, already "de-burred" hole.

Regular twist drill bits, tend to drill holes that are not quite round. The larger the hole, the more pronounced this is. But the Unibits, keep the drill bit centered all the time, so the hole is nice and round. Plus, the taper from going from step size to step size, tends to de-burr the hole. (these are actual step sizes, not a continuously variable drill bit, which looks more like a reamer than a drill bit. The ones I'm talking about have specific step sizes)

Plus, you can drill larger holes than your drill may be capable of holding. Also, if you stop as soon as you get to the hole size you need, then drill from the back side, you get a nicely de-burred hole on both sides.

One of the best drilling inventions ever. I have two Unibits, and they're about the only drill bits I need for front panels, besides one for drilling a pilot hole.

For drilling plastic, the problem with twist drill bits, is their "bite". If you were to look at the material you're drilling, as completely horizontal, the drill bit has a cutting edge, something like 32 degrees to the horizontal. It's also normally very sharp, like a knife edge. Once that edge, catches the plastic, it "bites" into it. Normally, this will rip the plastic out of your hands, or with brittle plastic, just snap it, and you have to start over (or in some cases, bandage your hand).

The fix for this, is oddly enough, a dull drill bit. A guy in the machine shop at AT&T showed this trick to me when I worked there in one of the labs. The only problem is, it's hard to describe.

If you look at the drill bit as having a line down the length of it in the center, that being the vertical line (being perpendicular) to the work piece (the front panel). This being the center axis.

Take your drill bit, and flatten that sharp edge, along the center axis. This flat edge, would also be perfectly perpendicular to the work piece, 90 degrees. So what you end up with is, instead of a "cutting edge" like a knife, you have a perfectly flat surface, scraping around in a circle, 90 degrees to the workpiece. This 90 degree edge, is what "scrapes" the hole in the plastic.

(you can flatten that edge, with a bench grinder, or a Dremel, or similar too. Just be sure to hold the drill bit, perfectly parallel to the grinding tool. It doesn't take much)

Of course, your drill bit isn't worth anything for drilling anything else after that, but who cares, you now have a plastic only bit. Buy some cheap drill bits for this. You "could" sharpen them again, but that's a lot of work when you can get cheap bits. I have one set just for plastic.

This works almost every time. They don't work so well in soft plastic, the harder the plastic, like Plexiglass, the better.

Unibits also work well for the plastics. But you have to be careful, and drill slow or it'll bite. And lubricate, lubricate, lubricate.

I wish I had more information on this, but I saw a guy in the lab at AT&T printing front panel items on a LASER printer, then transferring them to the panel. Like a decal. But I don't think he had anything special for doing it. I don't remember any special decal paper for that at the time. Maybe somebody here has an idea. It's possible, he used regular Elmer's white glue. let it dry, print on it, then get the paper off the back, so you're left with just the glue. I just don't remember exactly how he did it (the problem with not paying attention).

I do know they have special decal paper for that now (this was many years ago). So you can print on the LASER printer, then soak it in water, then transfer the toner "plastic" right to the front panel. Spray a protective coating on it, and presto-change-o! Terrific looking front panels.

The people that make the decal paper stuff, are the same people that make the iron on transfer stuff for PCB's. Like, when you the toner transfer for your silk screen on the PCB, you iron on the white plastic stuff to make the silk screen white instead of black (or several other colors). Those people. You can also use that iron on colored sheets, to change the color of the stuff on your front panel (if you used the LASER printer method).

Sorry, don't have their names in front of me, but you can probably find them. Or I could look it up if anybody needs it.

Something else I have done in the past, if it's worth the effort. Is salvage old remote control buttons. You can print the patterns you need on a PCB to duplicate the patters on the original remote PCB. Then using a "gold wash", low voltage electro-plating kit (you can find on the internet), plate those patterns so they don't oxidize.

This can give you the up/down/left/right/enter/numbers etc.... buttons so many devices has now. Basically, a customized rubber push button type panel. I've been saving old remote controls, and you can find them pretty cheap now. Heck, you can buy a new, no-contract phone or something, just for the keypad, for a couple bucks at Walmart. And sometimes even get a nice graphics LCD you can use. So buttons like that are easy to obtain. Old toys....

And doing this gives your project a professional look and feel to it. The gold wash/elector-plating kids is obviously a bit more expensive than they used to be. The kit I'm talking about, uses something like two AA batteries. But without the gold wash, the PCB copper will oxidize pretty quickly, rendering the buttons worthless. If you can come up with another way to keep the copper from oxidizing, that would work too.

The hardest problem with that project, was cutting the holes for the buttons. I tried to file the metal down into nice and neat little holes. But I ended up just cutting out a section, and filled it in with plastic that was cut to fit. Easier to cut than the metal.

I'd also recommend a "jewelers saw" for cutting small, odd shapes. These are the small saws that look like a "coping saw", they used to use them years ago, to cut out the background on coins. So, like on a Quarter, just the eagle would be there, with a ring around it. Very fine cutting saws. But they're sharp, cut through just about anything. great for odd shape holes.

I've got tons of tips in general. But this is about all I can think of right now, and am willing to type. Any questions just let me know and I'll try to be more helpful.

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