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Build Your Own PCB Milling Machine
mwandel writes "It used to be that one off amateur printed circuit boards were all etched in acid. A lot of companies nowadays use a special form of milling machine to mill them out of solid copper clad circuit boards. This guy Jonathan Westhues built his own PCB milling machine out of various parts, with a laminate trimmer as the milling head. Lots of other neat hacks on his Webpage as well."
More people need to be able to make their own parts out of steel and plastic. The problem is cost. It's curious that a country that is inventive as ours doesn't have some type of affordable CNC(computer numeric computation) milling machine.
Affordable metal cutting lathes are expensive too.
Good article for those that don't already have access to PCB milling equipment. There really is no reason to do the old-school etching method anymore, in fact, I don't even know any hobbyists that do that anymore. Milling equipment can be found, borrowed, or made pretty easily these days. I've even seen a working setup made from Lego Mindstorms and a cordless Dremel! Hey, it works and beats the heck outta the mask-and-acid roll of the dice method.
The best thing about this milling machine is that it built itself. The first version was controled by electronics on a breadboard. The second version uses much more sophisticated electronics on a PCB that had been milled by the first version of the machine. That is unbelievably elegant.
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Over here, (in school at least) we just print out the circuit diagram onto a transparency sheet (inkjet printer of course) and then just use a UV light to destroy the appropriate parts of the circuit.
Use some chemicals (stored in a safe location and brewable in your own home) and you've got a nice PCB for you to use.
As one of the members of the younger crowd of which you speak, I'd like to express my own (personal) opinion.
I'm certainly curious, and the multiple articles about home-made tools for dabbling with electronics certainly contribute to my curiosity. The problem, however, is two-fold. One, some of this is rather daunting for most beginners. I see some of the talk about people on here building their own circuitboards and such, and I'm a little intimidated, frankly. Two, I wouldn't know why to dabble in electronics, and the lack of an interesting and simple project just means that I won't get the basics that would let me move on to more advanced projects.
www.nutsandvolts.com certainly looks like an interesting resource, but I'm not sure it's as good for complete newbies such as myself. I'm going to sign up for a sample issue to better evaluate it, but I'm still afraid I'll miss a lot of critical background information.
You zap the moderators with a wand of humor! The moderators resist!
Milling machines are not an overkill or a solution for amateurs, they are a very good solution for inexpensive prototypes or production needed in small-mid volume.
:)
Acid etching produces a functional board, but it simply does not look good, and you can't make 100 boards that are exactly alike. The lines are almost straight, the edges are not perfect, and if you are on a contract to deliver a product, this is not an option. Examples of where a milling machine is one of the best solutions: a university lab where the researchers are under government/industry contract and are supposed to deliver a working prototype or a small business with a military contract (small volume products).
I worked for a startup company for a while, and part of my job was to work on a QuickCircuit milling machine, and that thing had milling bits that were 4 mils thick (comparable to hair). You can hardly reach this precision with acid etching. I also adapted the machine to dice wafers, which replaced the company's practice of using an exactoknife
If you are in the IC design business, testing cheaply is of primary importance. You can get a full setup for producing boards for less than $10K. How's that compared to billions of $$$ for setting up an IC production plant? And if you are in the RF design business, you need the precision so that a crappy board does not screw up your high-frequency measurements.
Of course, milling is no option for producing high-volume PCBs with many layers, but don't think that ASUS spent months to design such a board to test their new motherboard design. First they have to verify that design works, which is done with a cheap PCB design, one that would hook up the ICs. Only after that stage can the final PCB design begin.
As long as the Z80 or 68K processors are still in use, simple PCBs will be here, and we need a cheap and fast way to design and make them.
Scanners are essentially a flatbed plotter with only one axis of travel - cheap USB scanners can be had for under $30.00, buy a couple to get a two axis system, third axis could be a simple solinoid config. There would still be a lot of work left to do to get it all to go together, but it could be done (whether you stuck with the USB stuff, or just kept the stepper motor and drivers, then added you own custom interface). Also, back in the early 1980's there was a BYTE magazine article on building your own plotter (not that difficult)...
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On the contrary, large flatbed plotters are pretty popular for sign cutting, routing, etc. I used to work at a large custom print company, and we had a couple WILD plotters hooked up to a Xenix server.
At the time I left, they had 2 Zund tables, complete with conveyors, automatic sheet feeders, roll feeders, with a nifty camera hooked up to the cutting head that would track 1/4" dots on the media and compensate for stretching/shrinking that is common with the 3M vinyl that we used.
A while back I was looking through the Zund catalog, and they have all sorts of heads for their plotters, such as routers with z axis, laser, etc.
When we bought the Zunds, we sold the WILD tables to someone else (though I'm not sure why anyone would bother, they were known for their controller board problems.) I doubt that any functioning table would be trashed so readily.
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The most serious problem comes in from the really high-end etching systems. Photoresist is fine with ferric chloride, but when you start using something like an acid-peroxide etchant, it will actually eat many "resist" inks. The resist pens become TOTALLY useless, for example.
And so this is where the old technique of serigraphy comes in. This is the "screen-printing" that makes the name Printed Circuit Boards. The resist ink used on the actual board is usually just some form of lacquer, which holds up well to even the harshest etchants. A stencil is prepared on a screen, usually through a photographic process. Since the screen resist doesn't have to deal with the same harsh chemicals, it is generally much more environmentally conscious and cheaper than PC-Board photoresist.
I actually set up to do this method myself, in a semi-hobby context. I had some previous experience with serigraphy, and the acid/peroxide system was cheaper, far more effective, and much easier to dispose of than the ferric chloride. On the flip-side, it will eat virtually anything metallic and smells aweful (it isn't much of a health hazard except in the sulphuric/peroxide system, but should be ventilated nonetheless), so it's not for the faint of heart.
Hardware, software, and blinking lights!
But I used one of such machines. Nowadays they are absolutely, unconditionally useless.
Not true. I have also used such machines. They are actually very useful. Yeah you can't make a new motherboard for your PC with them, but for making quick prototypes they are great. You get your board the same day, and if you made any mistakes, you can fix them the same day and make another board, you don't have to spend time waiting for someone else to do things, the mail, etc.
As far as SMT goes, they can handle everything but the smallest of SMT parts. I built a prototype that had one such part, and afterwards I had to sit there under a stereomicroscope with an exacto knife cutting the traces in a half dozen places, but it really wasn't that bad. No one said my prototype had to use parts in packages that small anyways.
They are also killer for making quick interface boards, extender boards, etc. No you can't make anything you want with them, but just because they didn't work for your application doesn't mean they're useless. You're not getting four-layer boards with silkscreening for $30 anyways. If you want a board with a few connectors and minimal circuitry on it, you can have the finished thing in your hand by the end of the day and go back to doing your tests.
Since I've been able to get some use from one, they are clearly not "absolutely, unconditionally useless." Hell, there are still companies out there that use through-hole parts and phenolic PCBs in their final products. You don't need that dense of a circuit board when all you're doing is controlling a toaster.
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I could not agree more with what you said.
I would bet you in five years time, that DOS system will *still* be chugging along just fine.
I work with systems like this all the time in the robotics world. You do not have to be a gigahertz machine to spin steppers! There is *nothing* to be gained once you can process faster than the physics of mass and energy will allow.
Now, *most* (not all) of my clients are in business to make money. They want to set up a machine to crank out something, and do it for years. I often work with multi-millionaires who have quite "obsolete" machines toiling 24 hours a day making product. The machines, long since paid for, are working far better than the day they came out of the box, as by now, we have found the bugs and have the system tuned to repeatedly make perfect product.
I mentioned not all of my clients thought this way - there are some who just have to have the absolute cutting-edge stuff. Yes, they are the same guys who spend money they don't have, drive really fancy cars, live in fancy homes, and we spend our days raising money and debugging, then after a while, we have to explain why the money is gone and there is no product. Its not a skill I care to develop.
With one paradigm, continuous reliable production supports an almost perpetual research effort into making more product lines and the company tends to grow exponentially. With the other paradigm, our length of employment tends to approximate the total amount of funding received divided by the "burn rate".
Maybe this is flamebait - but I have been involved in both. And I have developed an intense distaste for the latter. There is something in me that writhes in acid when I have to face investors with nothing to show. I know the business books are full of advice on using "other people's money", but I would rather lose my own than take down all those other people with me.
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