PCB milling hell sunday extra


I’ve spent about 18 of the last 24 hours working on milling a PC board for my upcoming how-to. So far I’ve murdered several copper clad boards, built a hold down table, redesigned the board in eagle at least five times and snapped off a $15 half round engraving bit.

If you’re wondering, my new board milling table is a piece of MDF that I laser etched a .25″ grid onto, then added some aluminum strips to act as hold-downs. On the side of the strip opposite the board, I put thin slices of PC board to level out the hold downs. As usual, I’m building the board in eagle. To turn the board into something the mill can handle, I’m using pcb-gcode, a nice little g-code generation tool for eagle. I may switch methods later, but if I can get the settings tweaked, it’ll make my design to board milling process very fast.

[Scott] sent in the beginning of his attempt to build a frequency detector. He’s started out with just simple LCD matrix. Nothing intensely interesting just yet, but I like it when people send in stuff they’re working on.
If you haven’t checked out the Arduino yet, do it. It’s the easiest micro controller dev platform I’ve seen. If you’ve got one, now you can hook up a Wii-Nunchuck to it. If you like smaller and cheaper, check out [ladyada]‘s boarduino.

[eliot] wanted me to mention this video on hacking drive through speakers. It’s a bit cheesy – and all I could think of was Thunder Run – where the geek character swapped the crystals in the CB radios. (Warning, The FCC might have some expensive words for you if you get caught.) Update: this is what you get if you don’t watch the entire video and catch the joke about taking apart toasters.

Tomorrow I should be picking out some winners for my laser etched laptop (or whatever) offer. You can still win some free etching time! Just send in a tip! The winners are selected from the ones that get published on Hack-A-Day.

Comments

  1. Adam says:

    wow. that cb to fast food hack seems very tempting… but verrry bad.

  2. Dev says:

    Dude! I used to mill PCBs all the time (before i graduated to proper acid-etching them, the tech department at my school would let the juniors near the acid)… anyway – you don’t need to have a hold down table as such, just stick down your copper clad board with a few strips of double sided tape, then use a ruler or whatever to pry it of afterwards. works like a charm

  3. Tim Cooijmans says:

    Why don’t you use your laser etcher for routing PCBs? Is it not powerful enough to burn throug copper?

  4. jason says:

    you may want to check into a vacuum clamp for a table. woodworkers use ‘em for routing sometimes. they look fairly easy to make, and assuming you’ve got a sufficiently large air compressor handy it shouldn’t break the bank too badly to add a vacuum pump.

  5. srilyk says:

    Heh… I watched that CB video… it looked pretty amusing.

    That’s actually kind of frightening though, if someone creepy got a hold of that info (and their victim didn’t).

    What would be rather fun to do with that hack, though, is add a switch to the CB (or wire to an existing switch if it’s available) and put both crystals in the radio. Voila, now you have regular CB frequencies and the FF frequencies with just the flick of a switch. (I’m assuming the spike from switching across them wouldn’t be too harmful).

  6. FRKJ says:

    At Jim:

    The problem with that is that copper is such a good thermal conductor it will simply dissipate the heat and not burn through it. Would be nice though..

  7. Liam says:

    Re: the video -
    Someone explain this to me (I’m not an electrical engineer). CBs operate around 27 MHz. The crystal inside is 1.73 MHz according to them. The new crystal is 6.5536, which, when divided by 1.73, yields 3.788. 3.788 * 27 = 102 MHz. Does this mean that, for some reason, the circuit is nonlinear? Also, why are the leads of the crystal in the toaster so huge? Would the filters in the CB work at all in that frequency range?

    There seem to be a lot of problems with this, but I’m really hoping it’s true.

  8. What says:
  9. jayell says:

    I knew something was up when they said you couldn’t buy the crystals (see: Digikey) and had to get them from toasters.

    I take it that even if you had the right crystal, putting it in a CB wouldn’t work either? I was really hoping to be able to do this (and feel bad for all the suckers who took their toasters apart).

  10. jayell says:

    kindly disregard my last post. I’ve been had.
    there are easier (and more expensive) ways to do this, but they’re all still illegal.

    good prank, though.

  11. ... says:

    good luck trying to get to get your CB to transmit at any reasonable amount of power at 3 times the frequency it was designed for… Or finding a 6.53MHz crystal in ‘any appliance with a heater’…

    Also, I am somewhat surprised that there isn’t more of an outrage about people doing this and ‘giving hacking a bad name’–hey lets see if we can get some poor kid fired by putting words in his mouth!

  12. chr0n1c says:

    yo, if you can send me a dxf of the pcb i’ll do a mastercam toolpath for you in generic fanuc g-codes… it (the resulting code) works great in my emc2 machine controls.

  13. DCFluX says:

    Wow, and I thought I was nerdy when I bought a copy of Thunder run from region 2 just because it was on DVD.

    But in my defense it was filmed in the area where I live, whats your excuse?

  14. DCFluX says:

    Oh and arent CB’s AM and Drive Throughs FM?

  15. Ken_S. says:

    On “Field Day” (an annual Ham Radio Event) about two years ago, the president of the club was telling us he did that many years ago… he said “Would you like a muff-burger with that?” then it suddenly dawned on him how much trouble he could get in and has never done it since.

  16. rmrubin says:

    !!! WARNING PCB-GCODE USER !!!
    it ignores Z feed rates for plunges in traces milling. Thats right, you just plunged that $40 tool into copper and glass at lateral feed speeds. this is possibly only try when set to EMC mode.

    G01 Z-0.00500 F8.00000

    W T F has been posted to the pcb-gcode yahoo group.

    Also, its drill file formatting errors out for a couple reasons.

    But yeah besides that its awesome. use find and replace in the gcode files, ninjas.

  17. James Jarvis says:

    Since you have a laser cutter, there is a relatively easy way to make boards. Spray your copper clad board with a decent spray paint. Then use your laser to burn off the spray paintin areas where you want your board etched. Then etch as normal. To make drilling easier you can even put little tiny pin points in the center of your through hole holes. You’ll get a little depression in the copper and it will be perfect for giding your hand held dremel tool in to the center of the pad.

  18. Kyle says:

    Getting a boarduino would require a separate programmer…

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