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Idea's on a cheap, nice CNC project

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  • EVguru
    replied
    Take a look on http://www.milinst.co.uk/

    Their three axis machine is just about as simple as you can get. I think you may be able to download the plans.

    I used their code as a base, be re-wrote it entirely for the PCB drill at work (now mine!). We made our boards by photo etching, then drilled them. Double sided was usual and we made boards up to A4 in size.

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  • Stern
    replied
    From what I have gathered so far, the "milling bits" are actually special for PCB work, and look like a spade bit. Have used all forms of "prototyping" and breadboard is still my favorite (lends well to changes). Basically, the only boards I WILL make ore one-of or prototypes, and with the stuff I do, nothing beats having a "real board". I DONT use SMD as the cost is too high and you need special equip to do it right, especially when you get tight. I stick with DIP and discrete parts, and they can get very tight.
    Since working on a project that has tight dimensional restraints can mean making 8 boards for one project, making them myself is the only option.

    Contemplating using a motor spindle in place of my dremmel, but at $200-$1K they are way too stupidly priced for my budget. Will still kick the idea around a bit, and maybe if all goes will using a dremmel I can swap it out for a real spindle down the road.

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  • vincemulhollon
    replied
    Originally posted by Stern View Post
    Anyway, what I want is a small CNC type machine that will process small board (max size would be 12" x 24")
    Dremel will be too wiggly. Guess it depends on your precision. I've been using my mill. Copper cutting results are usually awful, but sometimes usable.

    As for all the "$50 is cheap" posts this is things like MMIC amplifiers using microstriplines, where the "pcb" is pretty much two very precise passes of the endmill to make perfect width traces, then chop gaps by hand for the MMICs themselves and DC blocking caps and everything else can be Manhattan style or dead bug style. I would hesitate to mill something complicated. So anyway WRT $50 is cheap, I'm doing things with $2 MMICs and fifty cents worth of chip caps, so no $50 is not cheap in comparison. Of course you can Manhattan microstripline easier than you can etch/mill it although soldering heat tends to screw up every glue I've tried. So I started sweating copper pads, and occasionally setting the boards on fire, its a craft or art more than a science.

    I've found thin PCB material to be a challenge to work-hold because its thin and flexy and nothing grabs and tears quite like copper. Nothing more frustrating than setting up the perfect trace accurate to a thousandth and the mill grabs and tears the thing clean off the board.

    The first time I tried this I was so unhappy with the result I swore it off, but ugly as it is, it actually works well enough. So I mill copper PCBs occasionally.

    This is microwave RF stuff, haven't used thru-hole for that stuff since before the 80s, so I'm all/mostly SMD so I have no assistance to provide WRT drilling thru holes. I've been told PCB fiberglass is super abrasive to drill so you need amazing, expensive drills which wear out very fast, or so they say.

    If I had the money, I imagine one of those 30K RPM air spindles would be really nice for PCB cutting.

    Cutters are not free, so there is likely some tradeoff point where its financially cheaper to just order out PCBs.

    I'd never one-off a PCB, I'd Manhattan or dead bug it, so there's a pretty narrow window where its too many to just grind it out by hand, but not enough for commercial production. My guess would be something like 5 to 20, where less than 5 just wire by hand, and more than 20 its hard to not come out ahead with commercial production.

    If you cut into the surface of the fiberglass, I've seen it behave like cold rolled, so it'll pretzel a little due to relieved stresses. Not all the time and not all materials, but it happens.

    The mill sometimes shoves little bits of swarf literally into the board, another annoyance.

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  • Jaakko Fagerlund
    replied
    Originally posted by Stern View Post
    Well, not sure how you came up with that figure, but when I entered data for a cheap board 45 mm x 50 mm double sided 1 oz I get $495 + $5 shipping ????

    This is ONE reason why I want to make my own, second is ONE mistake and the board is crap, and you just blew $500+ I can walk into a place here and get a prototype run of 10 for $400, which is STILL too much
    The figure is right from that page. When you scroll down a little, you see multiple options that you can add to your cart. That 50 x 50 mm double sided is the second from the top, costs 9.90 USD. Click on "add to cart" and it then asks you for board thickness, coating, E-testing, (color), and what else was there and shows the amount of money that some options cost extra.

    The last time i ordered I got 50 x 100 mm PCB's, 10 pieces, all E-tested and together with shipping I paid about 25 EUR. So at 2.5 EUR per ready made PCB with all the silk screens etc., just having to wait 1-3 weeks, it just isn't worth it doing at home anymore.

    Added: I calculated that your 16 x 6 inches board would be 286.82 USD plus shipping, this includes 5 PCB's, all tested.
    Last edited by Jaakko Fagerlund; 01-14-2014, 02:41 PM.

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  • Stern
    replied
    Originally posted by MotorradMike View Post
    If I want it shipped from Canada I go to Alberta printed circuits.
    They will make 2 double sided boards 5cm x 5cm for 51.50 in 3 days.

    I prefer an outfit in California but find it difficult to get electronic stuff across the border.
    Again, 5cm x 5cm is smaller than anything I would uses (4" x 4" would be small, 16" x 6" would be common) and when its all said and done, I end up paying a fortune for a prototype board that has a 95% chance of changing at LEAST 5 times lol.

    Anyway, this is really about the "project", not PC boards. For me to pay $2K-$5K for a CNC router is not going to happen.... EVER. For me to make one as a project .... far different story. I can take 300 years if I want to, spend money ONLY when I have it to spend, and more importantly .... have fun making it. After all, this is a HS forum, where people MAKE things for the joy of making them.


    Anyway, thanks to dp I found the CNC section of this site (seems any search I do just sits there and never ever stops ?) and have been able to look through some posts and try to learn some more about CNC

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  • MotorradMike
    replied
    If I want it shipped from Canada I go to Alberta printed circuits.
    They will make 2 double sided boards 5cm x 5cm for 51.50 in 3 days.

    I prefer an outfit in California but find it difficult to get electronic stuff across the border.

    Leave a comment:


  • Stern
    replied
    Originally posted by Jaakko Fagerlund View Post
    For cheap PCB's, check out http://imall.iteadstudio.com/open-pc...ototyping.html

    An example, 50x50 mm, 2 layer board, 10 pieces, 9.90 USD.
    Well, not sure how you came up with that figure, but when I entered data for a cheap board 45 mm x 50 mm double sided 1 oz I get $495 + $5 shipping ????

    This is ONE reason why I want to make my own, second is ONE mistake and the board is crap, and you just blew $500+ I can walk into a place here and get a prototype run of 10 for $400, which is STILL too much

    Leave a comment:


  • Jaakko Fagerlund
    replied
    For cheap PCB's, check out http://imall.iteadstudio.com/open-pc...ototyping.html

    An example, 50x50 mm, 2 layer board, 10 pieces, 9.90 USD.

    Leave a comment:


  • Stern
    replied
    duplicate
    Last edited by Stern; 01-14-2014, 11:10 AM. Reason: dupilcate

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  • Stern
    replied
    I have done a lot of surfing (and still at it) and actually never realized we have a section here (search didnt work for me). I have no desire to make PBC for a living or anything, but I DO have a need to make them time to time with projects I work on (like gauge clusters for my bike etc). ( have looked at lits and while they are probably great, I dont have $2K to drop on something like this (plus all the other stuff needed to run it).
    I am sure getting the resolution will be a challenge, but isnt that part of the fun of making something yourself (I could have bought a mill and press thats better than what I made myself, but really whats the point, its a hobby for me?)

    As for OSHPark and other "use our free software and we make the board for you" places, most are NOT cheap, most are size limited and almost all are in the US (nice shipping and duty fee's). Back in the day I had a PCB place make 10 block prototype runs for me all the time, now its freaking expensive for anything other than a final run. Used to do prototypes myself, but the lack of good materials now make it almost impossible.

    Anyway, figure this will be a good project for me to learn how to get my accuracy a lot tighter, even using the non professional equipment I have. My big headache is finding and putting the NON hardware into place (motors, drivers, software). I could make driver boards .... DONT want to. Would prefer pre made ones with software thats "plug and play" on windows and comparable with Design Spark (which I think generates G code, cant remember). Im sure an auto tool changer would be nice, but I would be happy with a dremmel used as the spindle.

    Anyway, going to check out the link dp, thanks a lot, the site search never seems to work well for me

    Leave a comment:


  • lwalker
    replied
    If you want to make a CNC machine for the fun of it, go ahead. But doing it for making PC boards is likely never going to be cost-effective. PCBs are simply too cheap. OSHPark etc., will make you 3 high quality boards for $5/sq. in total.

    I guess if you absolutely, positively need boards in hours/minutes instead of overnight or in a few weeks, a CNC mill might be a good idea, but only if you don't put a dollar value on your time.

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  • jlevie
    replied
    It would take a very precise (expensive) machine to make fine traces. A CAD package and a flat bed ink-jet resist printer would be more affordable. Or just use the services of one of the on-line prototype board makers.

    Leave a comment:


  • doorknob
    replied
    How about a Shapeoko 2?

    Plenty of people are using them to mill PC board traces.

    I started building a Shapeoko version 1 for that purpose, and just bought a 400-watt spindle on eBay to use with it.

    See https://www.inventables.com/technolo...kit-shapeoko-2

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  • outback
    replied
    From a builder of a number of CNC projects I can tell you that you don't need any kits. Just decide what you want for ways and spindle. From experience I can say dovetail ways can't be beat when it comes to rigid.

    For electronics all you need is a computer and software like Mach3. You will need to make a DC power supply usinga tororidal transformer, a breakout board and a driver board for each axis. For driver boards you can use Gecko drivers or use Chinese drivers board available on Ebay. I use Geckos for my industrial duty machines and the Chinese drivers for my prototype projects.

    Then you will need either stepper motors or servo motors to run your project.
    Jim

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  • dp
    replied
    You might drop a note in the CNC forum here: http://bbs.homeshopmachinist.net/for...ital-Machinist and take advantage of the CNC talent there.

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